[PATCH] usb: dwc3: gadget: Avoid race between dwc3 interrupt handler and irq thread handler
On some platfroms(like x86 platform), when one core is running the USB gadget irq thread handler by dwc3_thread_interrupt(), meanwhile another core also can respond other interrupts from dwc3 controller and modify the event buffer by dwc3_interrupt() function, that will cause getting the wrong event count in irq thread handler to make the USB function abnormal.
We should add spin_lock/unlock() in dwc3_check_event_buf() to avoid this race.
Signed-off-by: Baolin Wang baolin.wang@linaro.org --- drivers/usb/dwc3/gadget.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index 6785595..1a1e1f4 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -2894,10 +2894,13 @@ static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt) return IRQ_HANDLED; }
+ spin_lock(&dwc->lock); count = dwc3_readl(dwc->regs, DWC3_GEVNTCOUNT(0)); count &= DWC3_GEVNTCOUNT_MASK; - if (!count) + if (!count) { + spin_unlock(&dwc->lock); return IRQ_NONE; + }
evt->count = count; evt->flags |= DWC3_EVENT_PENDING; @@ -2914,6 +2917,7 @@ static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt) memcpy(evt->cache, evt->buf, count - amount);
dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), count); + spin_unlock(&dwc->lock);
return IRQ_WAKE_THREAD; }
Hi,
On 12/26/2016 04:01 PM, Baolin Wang wrote:
On some platfroms(like x86 platform), when one core is running the USB gadget irq thread handler by dwc3_thread_interrupt(), meanwhile another core also can respond other interrupts from dwc3 controller and modify the event buffer by dwc3_interrupt() function, that will cause getting the wrong event count in irq thread handler to make the USB function abnormal.
We should add spin_lock/unlock() in dwc3_check_event_buf() to avoid this race.
Why not spin_lock_irq ones? This lock seems to be used in both normal and interrupt threads. Or, I missed anything?
Best regards, Lu Baolu
Signed-off-by: Baolin Wang baolin.wang@linaro.org
drivers/usb/dwc3/gadget.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index 6785595..1a1e1f4 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -2894,10 +2894,13 @@ static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt) return IRQ_HANDLED; }
- spin_lock(&dwc->lock); count = dwc3_readl(dwc->regs, DWC3_GEVNTCOUNT(0)); count &= DWC3_GEVNTCOUNT_MASK;
- if (!count)
- if (!count) {
spin_unlock(&dwc->lock);- }
evt->count = count; evt->flags |= DWC3_EVENT_PENDING; @@ -2914,6 +2917,7 @@ static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt) memcpy(evt->cache, evt->buf, count - amount); dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), count);
- spin_unlock(&dwc->lock);
return IRQ_WAKE_THREAD; }
Hi,
On 27 December 2016 at 10:39, Lu Baolu baolu.lu@linux.intel.com wrote:
Hi,
On 12/26/2016 04:01 PM, Baolin Wang wrote:
On some platfroms(like x86 platform), when one core is running the USB gadget irq thread handler by dwc3_thread_interrupt(), meanwhile another core also can respond other interrupts from dwc3 controller and modify the event buffer by dwc3_interrupt() function, that will cause getting the wrong event count in irq thread handler to make the USB function abnormal.
We should add spin_lock/unlock() in dwc3_check_event_buf() to avoid this race.
Why not spin_lock_irq ones? This lock seems to be used in both normal and interrupt threads. Or, I missed anything?
I assumed there are no nested interrupts, when one core is running at interrupt context, then it can not respond any other interrupts, which means we don't need to disable local IRQ now, right?
Hi,
On 12/27/2016 10:58 AM, Baolin Wang wrote:
Hi,
On 27 December 2016 at 10:39, Lu Baolu baolu.lu@linux.intel.com wrote:
Hi,
On 12/26/2016 04:01 PM, Baolin Wang wrote:
On some platfroms(like x86 platform), when one core is running the USB gadget irq thread handler by dwc3_thread_interrupt(), meanwhile another core also can respond other interrupts from dwc3 controller and modify the event buffer by dwc3_interrupt() function, that will cause getting the wrong event count in irq thread handler to make the USB function abnormal.
We should add spin_lock/unlock() in dwc3_check_event_buf() to avoid this race.
Why not spin_lock_irq ones? This lock seems to be used in both normal and interrupt threads. Or, I missed anything?
I assumed there are no nested interrupts, when one core is running at interrupt context, then it can not respond any other interrupts, which means we don't need to disable local IRQ now, right?
Fair enough. Thanks.
Best regards, Lu Baolu
Hi,
Lu Baolu baolu.lu@linux.intel.com writes:
On 12/26/2016 04:01 PM, Baolin Wang wrote:
On some platfroms(like x86 platform), when one core is running the USB gadget irq thread handler by dwc3_thread_interrupt(), meanwhile another core also can respond other interrupts from dwc3 controller and modify the event buffer by dwc3_interrupt() function, that will cause getting the wrong event count in irq thread handler to make the USB function abnormal.
We should add spin_lock/unlock() in dwc3_check_event_buf() to avoid this race.
Why not spin_lock_irq ones? This lock seems to be used in both normal and interrupt threads. Or, I missed anything?
this is top half handler. Interrupts are already disabled.
2016-12-27 12:05 GMT+01:00 Felipe Balbi balbi@kernel.org:
Hi,
Lu Baolu baolu.lu@linux.intel.com writes:
On 12/26/2016 04:01 PM, Baolin Wang wrote:
On some platfroms(like x86 platform), when one core is running the USB gadget irq thread handler by dwc3_thread_interrupt(), meanwhile another core also can respond other interrupts from dwc3 controller and modify the event buffer by dwc3_interrupt() function, that will cause getting the wrong event count in irq thread handler to make the USB function abnormal.
We should add spin_lock/unlock() in dwc3_check_event_buf() to avoid this race.
Why not spin_lock_irq ones? This lock seems to be used in both normal and interrupt threads. Or, I missed anything?
this is top half handler. Interrupts are already disabled.
BTW, We don't use spin_lock in top half handler. Maybe we should/can switch all spin_lock_irqsave() to simple spin_lock() in the thread/callbacks? Or there is a reason to use irqsave() version?
BR Janusz
-- balbi
Hi,
Janusz Dziedzic janusz.dziedzic@gmail.com writes:
On some platfroms(like x86 platform), when one core is running the USB gadget irq thread handler by dwc3_thread_interrupt(), meanwhile another core also can respond other interrupts from dwc3 controller and modify the event buffer by dwc3_interrupt() function, that will cause getting the wrong event count in irq thread handler to make the USB function abnormal.
We should add spin_lock/unlock() in dwc3_check_event_buf() to avoid this race.
Why not spin_lock_irq ones? This lock seems to be used in both normal and interrupt threads. Or, I missed anything?
this is top half handler. Interrupts are already disabled.
BTW, We don't use spin_lock in top half handler. Maybe we should/can switch all spin_lock_irqsave() to simple spin_lock() in the thread/callbacks?
in theory, yes we've masked all interrupts from this controller for the duration of the thread handler. However this breaks networking gadgets. I can only guess network stack has a hard requirement to run with IRQs disabled.
Or there is a reason to use irqsave() version?
see above :-)
-----Original Message----- From: linux-usb-owner@vger.kernel.org [mailto:linux-usb- owner@vger.kernel.org] On Behalf Of Felipe Balbi Sent: Wednesday, December 28, 2016 8:19 AM To: Janusz Dziedzic janusz.dziedzic@gmail.com Cc: Lu Baolu baolu.lu@linux.intel.com; Baolin Wang baolin.wang@linaro.org; Greg KH gregkh@linuxfoundation.org; USB linux-usb@vger.kernel.org; LKML linux-kernel@vger.kernel.org; Linaro Kernel Mailman List linaro-kernel@lists.linaro.org; Mark Brown broonie@kernel.org Subject: Re: [PATCH] usb: dwc3: gadget: Avoid race between dwc3 interrupt handler and irq thread handler
Hi,
Janusz Dziedzic janusz.dziedzic@gmail.com writes:
On some platfroms(like x86 platform), when one core is running the
USB gadget
irq thread handler by dwc3_thread_interrupt(), meanwhile another
core also can
respond other interrupts from dwc3 controller and modify the event
buffer by
dwc3_interrupt() function, that will cause getting the wrong event
count in
irq thread handler to make the USB function abnormal.
We should add spin_lock/unlock() in dwc3_check_event_buf() to avoid
this race.
Why not spin_lock_irq ones? This lock seems to be used in both normal and interrupt threads. Or, I missed anything?
this is top half handler. Interrupts are already disabled.
BTW, We don't use spin_lock in top half handler. Maybe we should/can switch all spin_lock_irqsave() to simple spin_lock() in the thread/callbacks?
in theory, yes we've masked all interrupts from this controller for the duration of the thread handler. However this breaks networking gadgets. I can only guess network stack has a hard requirement to run with IRQs disabled.
Hi,
Is this version 3.00a of the core?
That version has a STAR where the interrupts cannot be masked. That results in similar symptoms to what you're seeing here.
Regards, John
On 12/28/2016 5:29 PM, John Youn wrote:
Janusz Dziedzic janusz.dziedzic@gmail.com writes:
On some platfroms(like x86 platform), when one core is running the
USB gadget
irq thread handler by dwc3_thread_interrupt(), meanwhile another
core also can
respond other interrupts from dwc3 controller and modify the event
buffer by
dwc3_interrupt() function, that will cause getting the wrong event
count in
irq thread handler to make the USB function abnormal.
We should add spin_lock/unlock() in dwc3_check_event_buf() to avoid
this race.
Why not spin_lock_irq ones? This lock seems to be used in both normal and interrupt threads. Or, I missed anything?
this is top half handler. Interrupts are already disabled.
BTW, We don't use spin_lock in top half handler. Maybe we should/can switch all spin_lock_irqsave() to simple spin_lock() in the thread/callbacks?
in theory, yes we've masked all interrupts from this controller for the duration of the thread handler. However this breaks networking gadgets. I can only guess network stack has a hard requirement to run with IRQs disabled.
Hi,
Is this version 3.00a of the core?
That version has a STAR where the interrupts cannot be masked. That results in similar symptoms to what you're seeing here. Regards, John
Didn't see any response to this. Just want to make sure this possibility is addressed as there is a workaround for it on mainline.
See the following commits for details:
d9fa4c63f766 ("usb: dwc3: core: add a event buffer cache") ebbb2d59398f ("usb: dwc3: gadget: use evt->cache for processing events") 65aca3205046 ("usb: dwc3: gadget: clear events in top-half handler") cf40b86b6ef6 ("usb: dwc3: Implement interrupt moderation") 28632b44d129 ("usb: dwc3: Workaround for irq mask issue")
Regards, John
Hi John,
On 6 January 2017 at 03:08, John Youn John.Youn@synopsys.com wrote:
On 12/28/2016 5:29 PM, John Youn wrote:
Janusz Dziedzic janusz.dziedzic@gmail.com writes:
> On some platfroms(like x86 platform), when one core is running the
USB gadget
> irq thread handler by dwc3_thread_interrupt(), meanwhile another
core also can
> respond other interrupts from dwc3 controller and modify the event
buffer by
> dwc3_interrupt() function, that will cause getting the wrong event
count in
> irq thread handler to make the USB function abnormal. > > We should add spin_lock/unlock() in dwc3_check_event_buf() to avoid
this race.
Why not spin_lock_irq ones? This lock seems to be used in both normal and interrupt threads. Or, I missed anything?
this is top half handler. Interrupts are already disabled.
BTW, We don't use spin_lock in top half handler. Maybe we should/can switch all spin_lock_irqsave() to simple spin_lock() in the thread/callbacks?
in theory, yes we've masked all interrupts from this controller for the duration of the thread handler. However this breaks networking gadgets. I can only guess network stack has a hard requirement to run with IRQs disabled.
Hi,
Is this version 3.00a of the core?
That version has a STAR where the interrupts cannot be masked. That results in similar symptoms to what you're seeing here.
Sorry for late reply. The version is 2.80a.
Regards, John
Didn't see any response to this. Just want to make sure this possibility is addressed as there is a workaround for it on mainline.
Thanks for reminding.
See the following commits for details:
d9fa4c63f766 ("usb: dwc3: core: add a event buffer cache") ebbb2d59398f ("usb: dwc3: gadget: use evt->cache for processing events") 65aca3205046 ("usb: dwc3: gadget: clear events in top-half handler") cf40b86b6ef6 ("usb: dwc3: Implement interrupt moderation") 28632b44d129 ("usb: dwc3: Workaround for irq mask issue")
2016-12-26 9:01 GMT+01:00 Baolin Wang baolin.wang@linaro.org:
On some platfroms(like x86 platform), when one core is running the USB gadget irq thread handler by dwc3_thread_interrupt(), meanwhile another core also can respond other interrupts from dwc3 controller and modify the event buffer by dwc3_interrupt() function, that will cause getting the wrong event count in irq thread handler to make the USB function abnormal.
We should add spin_lock/unlock() in dwc3_check_event_buf() to avoid this race.
Interesting, I always think we mask interrupt in dwc3_interrupt() by setting DWC3_GEVNTSIZ_INTMASK And unmask interrupt when we end dwc3_thread_interrupt().
So, we shouldn't get any IRQ from HW during dwc3_thread_interrupt(), or I miss something? Do you have some traces that indicate this masking will not work correctly?
BTW, what value you get when problem occured, 0xFFFC?
BR Janusz
Signed-off-by: Baolin Wang baolin.wang@linaro.org
drivers/usb/dwc3/gadget.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index 6785595..1a1e1f4 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -2894,10 +2894,13 @@ static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt) return IRQ_HANDLED; }
spin_lock(&dwc->lock); count = dwc3_readl(dwc->regs, DWC3_GEVNTCOUNT(0)); count &= DWC3_GEVNTCOUNT_MASK;
if (!count)
if (!count) {spin_unlock(&dwc->lock); return IRQ_NONE;} evt->count = count; evt->flags |= DWC3_EVENT_PENDING;@@ -2914,6 +2917,7 @@ static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt) memcpy(evt->cache, evt->buf, count - amount);
dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), count);
spin_unlock(&dwc->lock); return IRQ_WAKE_THREAD;}
1.7.9.5
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Hi,
On 27 December 2016 at 18:52, Janusz Dziedzic janusz.dziedzic@gmail.com wrote:
2016-12-26 9:01 GMT+01:00 Baolin Wang baolin.wang@linaro.org:
On some platfroms(like x86 platform), when one core is running the USB gadget irq thread handler by dwc3_thread_interrupt(), meanwhile another core also can respond other interrupts from dwc3 controller and modify the event buffer by dwc3_interrupt() function, that will cause getting the wrong event count in irq thread handler to make the USB function abnormal.
We should add spin_lock/unlock() in dwc3_check_event_buf() to avoid this race.
Interesting, I always think we mask interrupt in dwc3_interrupt() by setting DWC3_GEVNTSIZ_INTMASK And unmask interrupt when we end dwc3_thread_interrupt().
So, we shouldn't get any IRQ from HW during dwc3_thread_interrupt(), or I miss something? Do you have some traces that indicate this masking will not work correctly?
Yes, but we just masked the interrupts described in DEVTEN register, and we did not mask all the interrupts, like the endpoint command complete event, transfer complete event and so on, so we can still get interrupts.
BTW, what value you get when problem occured, 0xFFFC?
Yes, something like this, the event count become huge.
BR Janusz
Signed-off-by: Baolin Wang baolin.wang@linaro.org
drivers/usb/dwc3/gadget.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index 6785595..1a1e1f4 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -2894,10 +2894,13 @@ static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt) return IRQ_HANDLED; }
spin_lock(&dwc->lock); count = dwc3_readl(dwc->regs, DWC3_GEVNTCOUNT(0)); count &= DWC3_GEVNTCOUNT_MASK;
if (!count)
if (!count) {spin_unlock(&dwc->lock); return IRQ_NONE;} evt->count = count; evt->flags |= DWC3_EVENT_PENDING;@@ -2914,6 +2917,7 @@ static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt) memcpy(evt->cache, evt->buf, count - amount);
dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), count);
spin_unlock(&dwc->lock); return IRQ_WAKE_THREAD;}
1.7.9.5
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-- Janusz Dziedzic
Hi,
Baolin Wang baolin.wang@linaro.org writes:
Hi,
On 27 December 2016 at 18:52, Janusz Dziedzic janusz.dziedzic@gmail.com wrote:
2016-12-26 9:01 GMT+01:00 Baolin Wang baolin.wang@linaro.org:
On some platfroms(like x86 platform), when one core is running the USB gadget irq thread handler by dwc3_thread_interrupt(), meanwhile another core also can respond other interrupts from dwc3 controller and modify the event buffer by dwc3_interrupt() function, that will cause getting the wrong event count in irq thread handler to make the USB function abnormal.
We should add spin_lock/unlock() in dwc3_check_event_buf() to avoid this race.
Interesting, I always think we mask interrupt in dwc3_interrupt() by setting DWC3_GEVNTSIZ_INTMASK And unmask interrupt when we end dwc3_thread_interrupt().
So, we shouldn't get any IRQ from HW during dwc3_thread_interrupt(), or I miss something? Do you have some traces that indicate this masking will not work correctly?
Yes, but we just masked the interrupts described in DEVTEN register, and we did not mask all the interrupts, like the endpoint command complete event, transfer complete event and so on, so we can still get interrupts.
not true, we masked interrupts for the entire event buffer:
static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt) { struct dwc3 *dwc = evt->dwc; u32 count; u32 reg;
if (pm_runtime_suspended(dwc->dev)) { pm_runtime_get(dwc->dev); disable_irq_nosync(dwc->irq_gadget); dwc->pending_events = true; return IRQ_HANDLED; }
count = dwc3_readl(dwc->regs, DWC3_GEVNTCOUNT(0)); count &= DWC3_GEVNTCOUNT_MASK; if (!count) return IRQ_NONE;
evt->count = count; evt->flags |= DWC3_EVENT_PENDING;
/* Mask interrupt */ reg = dwc3_readl(dwc->regs, DWC3_GEVNTSIZ(0)); reg |= DWC3_GEVNTSIZ_INTMASK;
See here ?!?
dwc3_writel(dwc->regs, DWC3_GEVNTSIZ(0), reg);
return IRQ_WAKE_THREAD; }
BTW, what value you get when problem occured, 0xFFFC?
Yes, something like this, the event count become huge.
please send us tracepoint data. You probably need to compress it. Something like 256k of trace data is probably enough, so:
# mkdir -p /t # mount -t tracefs none /t # cd /t # echo 256 > buffer_size_kb # echo 1 > events/dwc3/enable # echo 0 > events/dwc3/dwc3_readl/enable # echo 0 > events/dwc3/dwc3_writel/enable
(reproduce)
# cp /t/trace /path/to/non-volatile/media/trace.txt
Hi,
On 27 December 2016 at 19:11, Felipe Balbi balbi@kernel.org wrote:
Hi,
Baolin Wang baolin.wang@linaro.org writes:
Hi,
On 27 December 2016 at 18:52, Janusz Dziedzic janusz.dziedzic@gmail.com wrote:
2016-12-26 9:01 GMT+01:00 Baolin Wang baolin.wang@linaro.org:
On some platfroms(like x86 platform), when one core is running the USB gadget irq thread handler by dwc3_thread_interrupt(), meanwhile another core also can respond other interrupts from dwc3 controller and modify the event buffer by dwc3_interrupt() function, that will cause getting the wrong event count in irq thread handler to make the USB function abnormal.
We should add spin_lock/unlock() in dwc3_check_event_buf() to avoid this race.
Interesting, I always think we mask interrupt in dwc3_interrupt() by setting DWC3_GEVNTSIZ_INTMASK And unmask interrupt when we end dwc3_thread_interrupt().
So, we shouldn't get any IRQ from HW during dwc3_thread_interrupt(), or I miss something? Do you have some traces that indicate this masking will not work correctly?
Yes, but we just masked the interrupts described in DEVTEN register, and we did not mask all the interrupts, like the endpoint command complete event, transfer complete event and so on, so we can still get interrupts.
not true, we masked interrupts for the entire event buffer:
Yes, you are right and I missed that. I should reproduce this problem and analyse the real reason.
static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt) { struct dwc3 *dwc = evt->dwc; u32 count; u32 reg;
if (pm_runtime_suspended(dwc->dev)) { pm_runtime_get(dwc->dev); disable_irq_nosync(dwc->irq_gadget); dwc->pending_events = true; return IRQ_HANDLED; } count = dwc3_readl(dwc->regs, DWC3_GEVNTCOUNT(0)); count &= DWC3_GEVNTCOUNT_MASK; if (!count) return IRQ_NONE; evt->count = count; evt->flags |= DWC3_EVENT_PENDING; /* Mask interrupt */ reg = dwc3_readl(dwc->regs, DWC3_GEVNTSIZ(0)); reg |= DWC3_GEVNTSIZ_INTMASK;See here ?!?
dwc3_writel(dwc->regs, DWC3_GEVNTSIZ(0), reg); return IRQ_WAKE_THREAD;}
BTW, what value you get when problem occured, 0xFFFC?
Yes, something like this, the event count become huge.
please send us tracepoint data. You probably need to compress it. Something like 256k of trace data is probably enough, so:
# mkdir -p /t # mount -t tracefs none /t # cd /t # echo 256 > buffer_size_kb # echo 1 > events/dwc3/enable # echo 0 > events/dwc3/dwc3_readl/enable # echo 0 > events/dwc3/dwc3_writel/enable
(reproduce)
# cp /t/trace /path/to/non-volatile/media/trace.txt
Okay, I try to do that. Thanks.
2016-12-27 13:16 GMT+01:00 Baolin Wang baolin.wang@linaro.org:
Hi,
On 27 December 2016 at 19:11, Felipe Balbi balbi@kernel.org wrote:
Hi,
Baolin Wang baolin.wang@linaro.org writes:
Hi,
On 27 December 2016 at 18:52, Janusz Dziedzic janusz.dziedzic@gmail.com wrote:
2016-12-26 9:01 GMT+01:00 Baolin Wang baolin.wang@linaro.org:
On some platfroms(like x86 platform), when one core is running the USB gadget irq thread handler by dwc3_thread_interrupt(), meanwhile another core also can respond other interrupts from dwc3 controller and modify the event buffer by dwc3_interrupt() function, that will cause getting the wrong event count in irq thread handler to make the USB function abnormal.
We should add spin_lock/unlock() in dwc3_check_event_buf() to avoid this race.
Interesting, I always think we mask interrupt in dwc3_interrupt() by setting DWC3_GEVNTSIZ_INTMASK And unmask interrupt when we end dwc3_thread_interrupt().
So, we shouldn't get any IRQ from HW during dwc3_thread_interrupt(), or I miss something? Do you have some traces that indicate this masking will not work correctly?
Yes, but we just masked the interrupts described in DEVTEN register, and we did not mask all the interrupts, like the endpoint command complete event, transfer complete event and so on, so we can still get interrupts.
not true, we masked interrupts for the entire event buffer:
Yes, you are right and I missed that. I should reproduce this problem and analyse the real reason.
static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt) { struct dwc3 *dwc = evt->dwc; u32 count; u32 reg;
if (pm_runtime_suspended(dwc->dev)) { pm_runtime_get(dwc->dev); disable_irq_nosync(dwc->irq_gadget); dwc->pending_events = true; return IRQ_HANDLED; } count = dwc3_readl(dwc->regs, DWC3_GEVNTCOUNT(0)); count &= DWC3_GEVNTCOUNT_MASK; if (!count) return IRQ_NONE; evt->count = count; evt->flags |= DWC3_EVENT_PENDING; /* Mask interrupt */ reg = dwc3_readl(dwc->regs, DWC3_GEVNTSIZ(0)); reg |= DWC3_GEVNTSIZ_INTMASK;See here ?!?
dwc3_writel(dwc->regs, DWC3_GEVNTSIZ(0), reg); return IRQ_WAKE_THREAD;}
BTW, what value you get when problem occured, 0xFFFC?
Yes, something like this, the event count become huge.
Probably you have little bit different code than current community version (depends how your PM works).
This is possible when we write: dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), 0); And after that dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), 4);
After that we will get 0xFFFC (-4).
Possible races: 1) dwc3_event_buffers_setup/dwc3_event_buffers_cleanup - write 0 2) dwc3_thread - write 4
While [1] could be called in PM work or UM context (init in Android case) spin_lock_irqsave() will only disable local irqs and still we could get IRQ on different core, next update evt->count and run thread...
So, seems your patch will solve this.
I am not sure this problem could be also visible in community current version.
Anyway, thanks for handling this.
BR Janusz
please send us tracepoint data. You probably need to compress it. Something like 256k of trace data is probably enough, so:
# mkdir -p /t # mount -t tracefs none /t # cd /t # echo 256 > buffer_size_kb # echo 1 > events/dwc3/enable # echo 0 > events/dwc3/dwc3_readl/enable # echo 0 > events/dwc3/dwc3_writel/enable
(reproduce)
# cp /t/trace /path/to/non-volatile/media/trace.txt
Okay, I try to do that. Thanks.
-- Baolin.wang Best Regards
On 28 December 2016 at 20:30, Janusz Dziedzic janusz.dziedzic@gmail.com wrote:
2016-12-27 13:16 GMT+01:00 Baolin Wang baolin.wang@linaro.org:
Hi,
On 27 December 2016 at 19:11, Felipe Balbi balbi@kernel.org wrote:
Hi,
Baolin Wang baolin.wang@linaro.org writes:
Hi,
On 27 December 2016 at 18:52, Janusz Dziedzic janusz.dziedzic@gmail.com wrote:
2016-12-26 9:01 GMT+01:00 Baolin Wang baolin.wang@linaro.org:
On some platfroms(like x86 platform), when one core is running the USB gadget irq thread handler by dwc3_thread_interrupt(), meanwhile another core also can respond other interrupts from dwc3 controller and modify the event buffer by dwc3_interrupt() function, that will cause getting the wrong event count in irq thread handler to make the USB function abnormal.
We should add spin_lock/unlock() in dwc3_check_event_buf() to avoid this race.
Interesting, I always think we mask interrupt in dwc3_interrupt() by setting DWC3_GEVNTSIZ_INTMASK And unmask interrupt when we end dwc3_thread_interrupt().
So, we shouldn't get any IRQ from HW during dwc3_thread_interrupt(), or I miss something? Do you have some traces that indicate this masking will not work correctly?
Yes, but we just masked the interrupts described in DEVTEN register, and we did not mask all the interrupts, like the endpoint command complete event, transfer complete event and so on, so we can still get interrupts.
not true, we masked interrupts for the entire event buffer:
Yes, you are right and I missed that. I should reproduce this problem and analyse the real reason.
static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt) { struct dwc3 *dwc = evt->dwc; u32 count; u32 reg;
if (pm_runtime_suspended(dwc->dev)) { pm_runtime_get(dwc->dev); disable_irq_nosync(dwc->irq_gadget); dwc->pending_events = true; return IRQ_HANDLED; } count = dwc3_readl(dwc->regs, DWC3_GEVNTCOUNT(0)); count &= DWC3_GEVNTCOUNT_MASK; if (!count) return IRQ_NONE; evt->count = count; evt->flags |= DWC3_EVENT_PENDING; /* Mask interrupt */ reg = dwc3_readl(dwc->regs, DWC3_GEVNTSIZ(0)); reg |= DWC3_GEVNTSIZ_INTMASK;See here ?!?
dwc3_writel(dwc->regs, DWC3_GEVNTSIZ(0), reg); return IRQ_WAKE_THREAD;}
BTW, what value you get when problem occured, 0xFFFC?
Yes, something like this, the event count become huge.
Probably you have little bit different code than current community version (depends how your PM works).
This is possible when we write: dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), 0); And after that dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), 4);
After that we will get 0xFFFC (-4).
Possible races:
- dwc3_event_buffers_setup/dwc3_event_buffers_cleanup - write 0
- dwc3_thread - write 4
While [1] could be called in PM work or UM context (init in Android case) spin_lock_irqsave() will only disable local irqs and still we could get IRQ on different core, next update evt->count and run thread...
Yeah, that's the possible races.
So, seems your patch will solve this.
I am not sure this problem could be also visible in community current version.
Anyway, thanks for handling this.
BR Janusz
please send us tracepoint data. You probably need to compress it. Something like 256k of trace data is probably enough, so:
# mkdir -p /t # mount -t tracefs none /t # cd /t # echo 256 > buffer_size_kb # echo 1 > events/dwc3/enable # echo 0 > events/dwc3/dwc3_readl/enable # echo 0 > events/dwc3/dwc3_writel/enable
(reproduce)
# cp /t/trace /path/to/non-volatile/media/trace.txt
Okay, I try to do that. Thanks.
-- Baolin.wang Best Regards
-- Janusz Dziedzic
Hi,
Baolin Wang baolin.wang@linaro.org writes:
On 28 December 2016 at 20:30, Janusz Dziedzic janusz.dziedzic@gmail.com wrote:
2016-12-27 13:16 GMT+01:00 Baolin Wang baolin.wang@linaro.org:
Hi,
On 27 December 2016 at 19:11, Felipe Balbi balbi@kernel.org wrote:
Hi,
Baolin Wang baolin.wang@linaro.org writes:
Hi,
On 27 December 2016 at 18:52, Janusz Dziedzic janusz.dziedzic@gmail.com wrote:
2016-12-26 9:01 GMT+01:00 Baolin Wang baolin.wang@linaro.org: > On some platfroms(like x86 platform), when one core is running the USB gadget > irq thread handler by dwc3_thread_interrupt(), meanwhile another core also can > respond other interrupts from dwc3 controller and modify the event buffer by > dwc3_interrupt() function, that will cause getting the wrong event count in > irq thread handler to make the USB function abnormal. > > We should add spin_lock/unlock() in dwc3_check_event_buf() to avoid this race. > Interesting, I always think we mask interrupt in dwc3_interrupt() by setting DWC3_GEVNTSIZ_INTMASK And unmask interrupt when we end dwc3_thread_interrupt().
So, we shouldn't get any IRQ from HW during dwc3_thread_interrupt(), or I miss something? Do you have some traces that indicate this masking will not work correctly?
Yes, but we just masked the interrupts described in DEVTEN register, and we did not mask all the interrupts, like the endpoint command complete event, transfer complete event and so on, so we can still get interrupts.
not true, we masked interrupts for the entire event buffer:
Yes, you are right and I missed that. I should reproduce this problem and analyse the real reason.
static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt) { struct dwc3 *dwc = evt->dwc; u32 count; u32 reg;
if (pm_runtime_suspended(dwc->dev)) { pm_runtime_get(dwc->dev); disable_irq_nosync(dwc->irq_gadget); dwc->pending_events = true; return IRQ_HANDLED; } count = dwc3_readl(dwc->regs, DWC3_GEVNTCOUNT(0)); count &= DWC3_GEVNTCOUNT_MASK; if (!count) return IRQ_NONE; evt->count = count; evt->flags |= DWC3_EVENT_PENDING; /* Mask interrupt */ reg = dwc3_readl(dwc->regs, DWC3_GEVNTSIZ(0)); reg |= DWC3_GEVNTSIZ_INTMASK;See here ?!?
dwc3_writel(dwc->regs, DWC3_GEVNTSIZ(0), reg); return IRQ_WAKE_THREAD;}
BTW, what value you get when problem occured, 0xFFFC?
Yes, something like this, the event count become huge.
Probably you have little bit different code than current community version (depends how your PM works).
This is possible when we write: dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), 0); And after that dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), 4);
After that we will get 0xFFFC (-4).
Possible races:
- dwc3_event_buffers_setup/dwc3_event_buffers_cleanup - write 0
- dwc3_thread - write 4
While [1] could be called in PM work or UM context (init in Android case) spin_lock_irqsave() will only disable local irqs and still we could get IRQ on different core, next update evt->count and run thread...
Yeah, that's the possible races.
and you have triggered this with mailine? How? We don't write to GEVNT* registers from PM code and we only allow runtime_suspend with cable dettached.
On 3 January 2017 at 20:33, Felipe Balbi balbi@kernel.org wrote:
Hi,
Baolin Wang baolin.wang@linaro.org writes:
On 28 December 2016 at 20:30, Janusz Dziedzic janusz.dziedzic@gmail.com wrote:
2016-12-27 13:16 GMT+01:00 Baolin Wang baolin.wang@linaro.org:
Hi,
On 27 December 2016 at 19:11, Felipe Balbi balbi@kernel.org wrote:
Hi,
Baolin Wang baolin.wang@linaro.org writes:
Hi,
On 27 December 2016 at 18:52, Janusz Dziedzic janusz.dziedzic@gmail.com wrote: > 2016-12-26 9:01 GMT+01:00 Baolin Wang baolin.wang@linaro.org: >> On some platfroms(like x86 platform), when one core is running the USB gadget >> irq thread handler by dwc3_thread_interrupt(), meanwhile another core also can >> respond other interrupts from dwc3 controller and modify the event buffer by >> dwc3_interrupt() function, that will cause getting the wrong event count in >> irq thread handler to make the USB function abnormal. >> >> We should add spin_lock/unlock() in dwc3_check_event_buf() to avoid this race. >> > Interesting, I always think we mask interrupt in dwc3_interrupt() by setting > DWC3_GEVNTSIZ_INTMASK > And unmask interrupt when we end dwc3_thread_interrupt(). > > So, we shouldn't get any IRQ from HW during dwc3_thread_interrupt(), > or I miss something? > Do you have some traces that indicate this masking will not work correctly?
Yes, but we just masked the interrupts described in DEVTEN register, and we did not mask all the interrupts, like the endpoint command complete event, transfer complete event and so on, so we can still get interrupts.
not true, we masked interrupts for the entire event buffer:
Yes, you are right and I missed that. I should reproduce this problem and analyse the real reason.
static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt) { struct dwc3 *dwc = evt->dwc; u32 count; u32 reg;
if (pm_runtime_suspended(dwc->dev)) { pm_runtime_get(dwc->dev); disable_irq_nosync(dwc->irq_gadget); dwc->pending_events = true; return IRQ_HANDLED; } count = dwc3_readl(dwc->regs, DWC3_GEVNTCOUNT(0)); count &= DWC3_GEVNTCOUNT_MASK; if (!count) return IRQ_NONE; evt->count = count; evt->flags |= DWC3_EVENT_PENDING; /* Mask interrupt */ reg = dwc3_readl(dwc->regs, DWC3_GEVNTSIZ(0)); reg |= DWC3_GEVNTSIZ_INTMASK;See here ?!?
dwc3_writel(dwc->regs, DWC3_GEVNTSIZ(0), reg); return IRQ_WAKE_THREAD;}
> BTW, what value you get when problem occured, 0xFFFC?
Yes, something like this, the event count become huge.
Probably you have little bit different code than current community version (depends how your PM works).
This is possible when we write: dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), 0); And after that dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), 4);
After that we will get 0xFFFC (-4).
Possible races:
- dwc3_event_buffers_setup/dwc3_event_buffers_cleanup - write 0
- dwc3_thread - write 4
While [1] could be called in PM work or UM context (init in Android case) spin_lock_irqsave() will only disable local irqs and still we could get IRQ on different core, next update evt->count and run thread...
Yeah, that's the possible races.
and you have triggered this with mailine? How? We don't write to GEVNT* registers from PM code and we only allow runtime_suspend with cable dettached.
Sorry for late reply since I am busy on other things. I just agreed with the possible races pointed by Janusz. I need to look at if these are happened on my platform and also I found some out of tree code which will clean the GEVNTCOUNT register when stop the gadget. I will check the mainline kernel and resend new patch if I make this problem clearly. Anyway thanks for your help and suggestion.
Hi,
Baolin Wang baolin.wang@linaro.org writes:
> On 27 December 2016 at 18:52, Janusz Dziedzic janusz.dziedzic@gmail.com wrote: >> 2016-12-26 9:01 GMT+01:00 Baolin Wang baolin.wang@linaro.org: >>> On some platfroms(like x86 platform), when one core is running the USB gadget >>> irq thread handler by dwc3_thread_interrupt(), meanwhile another core also can >>> respond other interrupts from dwc3 controller and modify the event buffer by >>> dwc3_interrupt() function, that will cause getting the wrong event count in >>> irq thread handler to make the USB function abnormal. >>> >>> We should add spin_lock/unlock() in dwc3_check_event_buf() to avoid this race. >>> >> Interesting, I always think we mask interrupt in dwc3_interrupt() by setting >> DWC3_GEVNTSIZ_INTMASK >> And unmask interrupt when we end dwc3_thread_interrupt(). >> >> So, we shouldn't get any IRQ from HW during dwc3_thread_interrupt(), >> or I miss something? >> Do you have some traces that indicate this masking will not work correctly? > > Yes, but we just masked the interrupts described in DEVTEN register, > and we did not mask all the interrupts, like the endpoint command > complete event, transfer complete event and so on, so we can still get > interrupts.
not true, we masked interrupts for the entire event buffer:
Yes, you are right and I missed that. I should reproduce this problem and analyse the real reason.
> static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt) > { > struct dwc3 *dwc = evt->dwc; > u32 count; > u32 reg; > > if (pm_runtime_suspended(dwc->dev)) { > pm_runtime_get(dwc->dev); > disable_irq_nosync(dwc->irq_gadget); > dwc->pending_events = true; > return IRQ_HANDLED; > } > > count = dwc3_readl(dwc->regs, DWC3_GEVNTCOUNT(0)); > count &= DWC3_GEVNTCOUNT_MASK; > if (!count) > return IRQ_NONE; > > evt->count = count; > evt->flags |= DWC3_EVENT_PENDING; > > /* Mask interrupt */ > reg = dwc3_readl(dwc->regs, DWC3_GEVNTSIZ(0)); > reg |= DWC3_GEVNTSIZ_INTMASK;
See here ?!?
> dwc3_writel(dwc->regs, DWC3_GEVNTSIZ(0), reg); > > return IRQ_WAKE_THREAD; > }
>> BTW, what value you get when problem occured, 0xFFFC? > > Yes, something like this, the event count become huge.
Probably you have little bit different code than current community version (depends how your PM works).
This is possible when we write: dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), 0); And after that dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), 4);
After that we will get 0xFFFC (-4).
Possible races:
- dwc3_event_buffers_setup/dwc3_event_buffers_cleanup - write 0
- dwc3_thread - write 4
While [1] could be called in PM work or UM context (init in Android case) spin_lock_irqsave() will only disable local irqs and still we could get IRQ on different core, next update evt->count and run thread...
Yeah, that's the possible races.
and you have triggered this with mailine? How? We don't write to GEVNT* registers from PM code and we only allow runtime_suspend with cable dettached.
Sorry for late reply since I am busy on other things. I just agreed with the possible races pointed by Janusz. I need to look at if these are happened on my platform and also I found some out of tree code which will clean the GEVNTCOUNT register when stop the gadget. I will check the mainline kernel and resend new patch if I make this problem clearly. Anyway thanks for your help and suggestion.
IOW, you sent me a patch to be integrated in the tree which everybody in the whole world uses and you didn't even test anything in that very tree? How am I supposed to trust you're sending me tested patches from now on?
Clearly you have no empathy for those working countless hours to keep this stable and working. If you're ready to send me a completely untested patch and claim that it's fixing a race condition you have never seen for yourself, it becomes difficult to trust any patches you're sending me.
You should know better. Your employer has people on staff who are able to clarify all these "details". You should never, ever send me patches like this again. Mark, himself, has a long track record of contributing to upstream development; maybe you should have a discussion with him offline about this.
Hi,
On 5 January 2017 at 17:26, Felipe Balbi balbi@kernel.org wrote:
Hi,
Baolin Wang baolin.wang@linaro.org writes:
>> On 27 December 2016 at 18:52, Janusz Dziedzic janusz.dziedzic@gmail.com wrote: >>> 2016-12-26 9:01 GMT+01:00 Baolin Wang baolin.wang@linaro.org: >>>> On some platfroms(like x86 platform), when one core is running the USB gadget >>>> irq thread handler by dwc3_thread_interrupt(), meanwhile another core also can >>>> respond other interrupts from dwc3 controller and modify the event buffer by >>>> dwc3_interrupt() function, that will cause getting the wrong event count in >>>> irq thread handler to make the USB function abnormal. >>>> >>>> We should add spin_lock/unlock() in dwc3_check_event_buf() to avoid this race. >>>> >>> Interesting, I always think we mask interrupt in dwc3_interrupt() by setting >>> DWC3_GEVNTSIZ_INTMASK >>> And unmask interrupt when we end dwc3_thread_interrupt(). >>> >>> So, we shouldn't get any IRQ from HW during dwc3_thread_interrupt(), >>> or I miss something? >>> Do you have some traces that indicate this masking will not work correctly? >> >> Yes, but we just masked the interrupts described in DEVTEN register, >> and we did not mask all the interrupts, like the endpoint command >> complete event, transfer complete event and so on, so we can still get >> interrupts. > > not true, we masked interrupts for the entire event buffer:
Yes, you are right and I missed that. I should reproduce this problem and analyse the real reason.
> >> static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt) >> { >> struct dwc3 *dwc = evt->dwc; >> u32 count; >> u32 reg; >> >> if (pm_runtime_suspended(dwc->dev)) { >> pm_runtime_get(dwc->dev); >> disable_irq_nosync(dwc->irq_gadget); >> dwc->pending_events = true; >> return IRQ_HANDLED; >> } >> >> count = dwc3_readl(dwc->regs, DWC3_GEVNTCOUNT(0)); >> count &= DWC3_GEVNTCOUNT_MASK; >> if (!count) >> return IRQ_NONE; >> >> evt->count = count; >> evt->flags |= DWC3_EVENT_PENDING; >> >> /* Mask interrupt */ >> reg = dwc3_readl(dwc->regs, DWC3_GEVNTSIZ(0)); >> reg |= DWC3_GEVNTSIZ_INTMASK; > > See here ?!? > >> dwc3_writel(dwc->regs, DWC3_GEVNTSIZ(0), reg); >> >> return IRQ_WAKE_THREAD; >> } > >>> BTW, what value you get when problem occured, 0xFFFC? >> >> Yes, something like this, the event count become huge. >
Probably you have little bit different code than current community version (depends how your PM works).
This is possible when we write: dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), 0); And after that dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), 4);
After that we will get 0xFFFC (-4).
Possible races:
- dwc3_event_buffers_setup/dwc3_event_buffers_cleanup - write 0
- dwc3_thread - write 4
While [1] could be called in PM work or UM context (init in Android case) spin_lock_irqsave() will only disable local irqs and still we could get IRQ on different core, next update evt->count and run thread...
Yeah, that's the possible races.
and you have triggered this with mailine? How? We don't write to GEVNT* registers from PM code and we only allow runtime_suspend with cable dettached.
Sorry for late reply since I am busy on other things. I just agreed with the possible races pointed by Janusz. I need to look at if these are happened on my platform and also I found some out of tree code which will clean the GEVNTCOUNT register when stop the gadget. I will check the mainline kernel and resend new patch if I make this problem clearly. Anyway thanks for your help and suggestion.
IOW, you sent me a patch to be integrated in the tree which everybody in the whole world uses and you didn't even test anything in that very tree? How am I supposed to trust you're sending me tested patches from now on?
Clearly you have no empathy for those working countless hours to keep this stable and working. If you're ready to send me a completely untested patch and claim that it's fixing a race condition you have never seen for yourself, it becomes difficult to trust any patches you're sending me.
I am sure I send you every patch was tested on my vendor platform and I saw the problem on my platform. But like my said I missed something that we have masked all interrupts in the dwc3 interrupt handler, so the real reason maybe caused by some out of tree code on my vendor platform which will clean the GEVNTCOUNT register when stop the gadget. Moreover I did not only do this one thing, and some other problem I also need time to test and investigate. So I think I need some time to make things clear, then I can send you one better patch with the correct explanation, am I wrong here?
You should know better. Your employer has people on staff who are able to clarify all these "details". You should never, ever send me patches like this again. Mark, himself, has a long track record of contributing to upstream development; maybe you should have a discussion with him offline about this.
-- balbi
Hi,
Baolin Wang baolin.wang@linaro.org writes:
[...]
and you have triggered this with mailine? How? We don't write to GEVNT* registers from PM code and we only allow runtime_suspend with cable dettached.
Sorry for late reply since I am busy on other things. I just agreed with the possible races pointed by Janusz. I need to look at if these are happened on my platform and also I found some out of tree code which will clean the GEVNTCOUNT register when stop the gadget. I will check the mainline kernel and resend new patch if I make this problem clearly. Anyway thanks for your help and suggestion.
IOW, you sent me a patch to be integrated in the tree which everybody in the whole world uses and you didn't even test anything in that very tree? How am I supposed to trust you're sending me tested patches from now on?
Clearly you have no empathy for those working countless hours to keep this stable and working. If you're ready to send me a completely untested patch and claim that it's fixing a race condition you have never seen for yourself, it becomes difficult to trust any patches you're sending me.
I am sure I send you every patch was tested on my vendor platform and I saw the problem on my platform. But like my said I missed something that we have masked all interrupts in the dwc3 interrupt handler, so the real reason maybe caused by some out of tree code on my vendor platform which will clean the GEVNTCOUNT register when stop the gadget. Moreover I did not only do this one thing, and some other
and this is the very problem I'm referring to. If you have changes on DWC3 on your "vendor tree" you're testing *mainline* DWC3. Which kernel is your tree even based on?
problem I also need time to test and investigate. So I think I need some time to make things clear, then I can send you one better patch with the correct explanation, am I wrong here?
you're wrong to assume your vendor tree *with changes on DWC3 driver* is equivalent to testing *mainline*. That just doesn't add up.
If you were adding just platform init code (something under your mach-* directory, some DTS, etc) that's fine. But you have changes on the USB peripheral controller driver. This makes me rather uneasy about your patches. I mean, if you have changes to DWC3, what other changes do you have there? Also, if your changes are in PM code, which we have support in upstream, this suggests that you're using older kernel from the time when we didn't have PM support upstream. This means you're using something pre-v4.8. Which kernel are you using?
cheers
Hi,
On 5 January 2017 at 19:19, Felipe Balbi balbi@kernel.org wrote:
Hi,
Baolin Wang baolin.wang@linaro.org writes:
[...]
and you have triggered this with mailine? How? We don't write to GEVNT* registers from PM code and we only allow runtime_suspend with cable dettached.
Sorry for late reply since I am busy on other things. I just agreed with the possible races pointed by Janusz. I need to look at if these are happened on my platform and also I found some out of tree code which will clean the GEVNTCOUNT register when stop the gadget. I will check the mainline kernel and resend new patch if I make this problem clearly. Anyway thanks for your help and suggestion.
IOW, you sent me a patch to be integrated in the tree which everybody in the whole world uses and you didn't even test anything in that very tree? How am I supposed to trust you're sending me tested patches from now on?
Clearly you have no empathy for those working countless hours to keep this stable and working. If you're ready to send me a completely untested patch and claim that it's fixing a race condition you have never seen for yourself, it becomes difficult to trust any patches you're sending me.
I am sure I send you every patch was tested on my vendor platform and I saw the problem on my platform. But like my said I missed something that we have masked all interrupts in the dwc3 interrupt handler, so the real reason maybe caused by some out of tree code on my vendor platform which will clean the GEVNTCOUNT register when stop the gadget. Moreover I did not only do this one thing, and some other
and this is the very problem I'm referring to. If you have changes on DWC3 on your "vendor tree" you're testing *mainline* DWC3. Which kernel is your tree even based on?
Kernel version is 4.4.
problem I also need time to test and investigate. So I think I need some time to make things clear, then I can send you one better patch with the correct explanation, am I wrong here?
you're wrong to assume your vendor tree *with changes on DWC3 driver* is equivalent to testing *mainline*. That just doesn't add up.
If you were adding just platform init code (something under your mach-* directory, some DTS, etc) that's fine. But you have changes on the USB peripheral controller driver. This makes me rather uneasy about your patches. I mean, if you have changes to DWC3, what other changes do you have there? Also, if your changes are in PM code, which we have support
As below code shows up, we will clean the event count register when waiting for stop the controller (these out of tree code are not added by me, so I did not know what's problem it fix before). It is one possible race on my vendor tree. static int dwc3_gadget_run_stop(struct dwc3 *dwc, int is_on, int suspend) { u32 reg; u32 timeout = 500, i;
if (pm_runtime_suspended(dwc->dev)) return 0;
reg = dwc3_readl(dwc->regs, DWC3_DCTL); if (is_on) { if (dwc->revision <= DWC3_REVISION_187A) { reg &= ~DWC3_DCTL_TRGTULST_MASK; reg |= DWC3_DCTL_TRGTULST_RX_DET; }
if (dwc->revision >= DWC3_REVISION_194A) reg &= ~DWC3_DCTL_KEEP_CONNECT;
reg = dwc3_readl(dwc->regs, DWC3_DCTL); reg |= DWC3_DCTL_RUN_STOP;
if (dwc->has_hibernation) reg |= DWC3_DCTL_KEEP_CONNECT;
dwc->pullups_connected = true; } else { reg &= ~DWC3_DCTL_RUN_STOP;
if (dwc->has_hibernation && !suspend) reg &= ~DWC3_DCTL_KEEP_CONNECT;
dwc->pullups_connected = false; }
dwc3_writel(dwc->regs, DWC3_DCTL, reg);
do { reg = dwc3_readl(dwc->regs, DWC3_DSTS); if (is_on) { if (!(reg & DWC3_DSTS_DEVCTRLHLT)) break; } else { if (reg & DWC3_DSTS_DEVCTRLHLT) break;
/* * Per databook, Software needs to acknowledge the * events that are generated (by writing to GEVNTCOUNTn) * while it is waiting for this bit to be set to 1. */ for (i = 0; i < dwc->num_event_buffers; i++) { reg = dwc3_readl(dwc->regs, DWC3_GEVNTCOUNT(i)); if (reg) dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(i), reg); } }
timeout--; if (!timeout) return -ETIMEDOUT; udelay(1); } while (1);
dwc3_trace(trace_dwc3_gadget, "gadget %s data soft-%s", dwc->gadget_driver ? dwc->gadget_driver->function : "no-function", is_on ? "connect" : "disconnect");
return 0; }
Usually if I found one problem on my vendor tree, then I will check if the mainline kernel has the same problem, if it is I will send one patch tested on my vendor tree to fix that. Usually it can work. But for this patch, I made one mistake that I missed we mask the interrupts as you pointed out, so the reason of the problem I described in commit log was wrong. I need to check if it is caused by some out of tree code or mainline kernel also has the same problem. Then I can send one correct patch with correct reason. But as Mark's suggestion, I will change to test and solve problem on one upstreamed board, so that it can make sure the problems are not caused by out of tree code any more. Sorry for noise again.
in upstream, this suggests that you're using older kernel from the time when we didn't have PM support upstream. This means you're using something pre-v4.8. Which kernel are you using?
cheers
-- balbi
Hi,
Janusz Dziedzic janusz.dziedzic@gmail.com writes:
2016-12-26 9:01 GMT+01:00 Baolin Wang baolin.wang@linaro.org:
On some platfroms(like x86 platform), when one core is running the USB gadget irq thread handler by dwc3_thread_interrupt(), meanwhile another core also can respond other interrupts from dwc3 controller and modify the event buffer by dwc3_interrupt() function, that will cause getting the wrong event count in irq thread handler to make the USB function abnormal.
We should add spin_lock/unlock() in dwc3_check_event_buf() to avoid this race.
Interesting, I always think we mask interrupt in dwc3_interrupt() by setting DWC3_GEVNTSIZ_INTMASK And unmask interrupt when we end dwc3_thread_interrupt().
So, we shouldn't get any IRQ from HW during dwc3_thread_interrupt(), or I miss something? Do you have some traces that indicate this masking will not work correctly?
that's the very question I have. We are already masking interrupts from this controller. The only thing this could race with is usb_ep_queue(), but that gets nowhere close to anything we're doing in the top half handler, so there's really no danger of anything bad happening.
I'd like to see traces as well.
linaro-kernel@lists.linaro.org
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Baolin Wang -
Felipe Balbi -
Janusz Dziedzic -
John Youn -
Lu Baolu