[Linux-stable-mirror] [PATCH] uas: Unblock scsi-requests on failure to alloc streams in post_reset
If we return 1 from our post_reset handler, then our disconnect handler will be called immediately afterwards. Since pre_reset blocks all scsi requests our disconnect handler will then hang in the scsi_remove_host call.
This is esp. bad because our disconnect handler hanging for ever also stops the USB subsys from enumerating any new USB devices, causes commands like lsusb to hang, etc.
In practice this happens when unplugging some uas devices because the hub code may see the device as needing a warm-reset and calls usb_reset_device before seeing the disconnect. In this case uas_configure_endpoints fails with -ENODEV. We do not want to print an error for this, so this commit also silences the shost_printk for -ENODEV.
BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1531966 Cc: stable@vger.kernel.org Fixes: 8d51444cdd06 ("uas: Not being able to alloc streams ... is an error") Signed-off-by: Hans de Goede hdegoede@redhat.com --- drivers/usb/storage/uas.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/storage/uas.c b/drivers/usb/storage/uas.c index 5d04c40ee40a..5471422aa1ab 100644 --- a/drivers/usb/storage/uas.c +++ b/drivers/usb/storage/uas.c @@ -1077,9 +1077,13 @@ static int uas_post_reset(struct usb_interface *intf)
err = uas_configure_endpoints(devinfo); if (err) { - shost_printk(KERN_ERR, shost, - "%s: alloc streams error %d after reset", - __func__, err); + if (err != -ENODEV) { + shost_printk(KERN_ERR, shost, + "%s: alloc streams error %d after reset", + __func__, err); + } + /* So that scsi_remove_host in uas_disconnect does not hang */ + scsi_unblock_requests(shost); return 1; }
Am Mittwoch, den 10.01.2018, 08:13 +0100 schrieb Hans de Goede:
If we return 1 from our post_reset handler, then our disconnect handler will be called immediately afterwards. Since pre_reset blocks all scsi requests our disconnect handler will then hang in the scsi_remove_host call.
Hi Hans,
it seems to me that the diagnosis is spot on. But why do we keep different code paths at all in this case? I do not see the point of not reporting the reset to the SCSI subsystem, even if we are not operational afterwards. So how about something like this?
From 4d1e26154bc5d09913bfba34d7adc39cce98d20a Mon Sep 17 00:00:00 2001
From: Oliver Neukum oneukum@suse.com Date: Wed, 10 Jan 2018 16:16:03 +0100 Subject: [PATCH] usb: uas: unconditionally bring back host after reset
Quoting Hans:
If we return 1 from our post_reset handler, then our disconnect handler will be called immediately afterwards. Since pre_reset blocks all scsi requests our disconnect handler will then hang in the scsi_remove_host call.
This is esp. bad because our disconnect handler hanging for ever also stops the USB subsys from enumerating any new USB devices, causes commands like lsusb to hang, etc.
In practice this happens when unplugging some uas devices because the hub code may see the device as needing a warm-reset and calls usb_reset_device before seeing the disconnect. In this case uas_configure_endpoints fails with -ENODEV. We do not want to print an error for this, so this commit also silences the shost_printk for -ENODEV.
ENDQUOTE
However, if we do that we better drop any unconditional execution and report to the SCSI subsystem that we have undergone a reset but we are not operational now.
Signed-off-by: Oliver Neukum oneukum@suse.com Reported-by: Hans de Goede hdegoede@redhat.com --- Makefile | 2 +- drivers/usb/storage/uas.c | 7 +++---- 2 files changed, 4 insertions(+), 5 deletions(-)
diff --git a/drivers/usb/storage/uas.c b/drivers/usb/storage/uas.c index 5d04c40ee40a..3b1b9695177a 100644 --- a/drivers/usb/storage/uas.c +++ b/drivers/usb/storage/uas.c @@ -1076,20 +1076,19 @@ static int uas_post_reset(struct usb_interface *intf) return 0; err = uas_configure_endpoints(devinfo); - if (err) { + if (err && err != ENODEV) shost_printk(KERN_ERR, shost, "%s: alloc streams error %d after reset", __func__, err); - return 1; - } + /* we must unblock the host in every case lest we deadlock */ spin_lock_irqsave(shost->host_lock, flags); scsi_report_bus_reset(shost, 0); spin_unlock_irqrestore(shost->host_lock, flags); scsi_unblock_requests(shost); - return 0; + return err ? 1 : 0; } static int uas_suspend(struct usb_interface *intf, pm_message_t message) -- 2.13.6
Hi,
On 10-01-18 16:23, Oliver Neukum wrote:
Am Mittwoch, den 10.01.2018, 08:13 +0100 schrieb Hans de Goede:
If we return 1 from our post_reset handler, then our disconnect handler will be called immediately afterwards. Since pre_reset blocks all scsi requests our disconnect handler will then hang in the scsi_remove_host call.
Hi Hans,
it seems to me that the diagnosis is spot on. But why do we keep different code paths at all in this case? I do not see the point of not reporting the reset to the SCSI subsystem, even if we are not operational afterwards. So how about something like this?
Sure, works for me :)
Regards,
Hans
From 4d1e26154bc5d09913bfba34d7adc39cce98d20a Mon Sep 17 00:00:00 2001 From: Oliver Neukum oneukum@suse.com Date: Wed, 10 Jan 2018 16:16:03 +0100 Subject: [PATCH] usb: uas: unconditionally bring back host after reset
Quoting Hans:
If we return 1 from our post_reset handler, then our disconnect handler will be called immediately afterwards. Since pre_reset blocks all scsi requests our disconnect handler will then hang in the scsi_remove_host call.
This is esp. bad because our disconnect handler hanging for ever also stops the USB subsys from enumerating any new USB devices, causes commands like lsusb to hang, etc.
In practice this happens when unplugging some uas devices because the hub code may see the device as needing a warm-reset and calls usb_reset_device before seeing the disconnect. In this case uas_configure_endpoints fails with -ENODEV. We do not want to print an error for this, so this commit also silences the shost_printk for -ENODEV.
ENDQUOTE
However, if we do that we better drop any unconditional execution and report to the SCSI subsystem that we have undergone a reset but we are not operational now.
Signed-off-by: Oliver Neukum oneukum@suse.com Reported-by: Hans de Goede hdegoede@redhat.com
Makefile | 2 +- drivers/usb/storage/uas.c | 7 +++---- 2 files changed, 4 insertions(+), 5 deletions(-)
diff --git a/drivers/usb/storage/uas.c b/drivers/usb/storage/uas.c index 5d04c40ee40a..3b1b9695177a 100644 --- a/drivers/usb/storage/uas.c +++ b/drivers/usb/storage/uas.c @@ -1076,20 +1076,19 @@ static int uas_post_reset(struct usb_interface *intf) return 0; err = uas_configure_endpoints(devinfo);
- if (err) {
- if (err && err != ENODEV)
shost_printk(KERN_ERR, shost, "%s: alloc streams error %d after reset", __func__, err);
return 1;- }
- /* we must unblock the host in every case lest we deadlock */
spin_lock_irqsave(shost->host_lock, flags); scsi_report_bus_reset(shost, 0); spin_unlock_irqrestore(shost->host_lock, flags); scsi_unblock_requests(shost);
- return 0;
- return err ? 1 : 0;
} static int uas_suspend(struct usb_interface *intf, pm_message_t message) -- 2.13.6
linux-stable-mirror@lists.linaro.org
-
Hans de Goede -
Oliver Neukum