August 2025 - Linux-stable-mirror

[PATCH 6.12] Drivers: hv: Make the sysfs node size for the ring buffer dynamic

by Naman Jain

The ring buffer size varies across VMBus channels. The size of sysfs node for the ring buffer is currently hardcoded to 4 MB. Userspace clients either use fstat() or hardcode this size for doing mmap(). To address this, make the sysfs node size dynamic to reflect the actual ring buffer size for each channel. This will ensure that fstat() on ring sysfs node always returns the correct size of ring buffer. This is a backport of the upstream commit 65995e97a1ca ("Drivers: hv: Make the sysfs node size for the ring buffer dynamic") with modifications, as the original patch has missing dependencies on kernel v6.12.x. The structure "struct attribute_group" does not have bin_size field in v6.12.x kernel so the logic of configuring size of sysfs node for ring buffer has been moved to vmbus_chan_bin_attr_is_visible(). Original change was not a fix, but it needs to be backported to fix size related discrepancy caused by the commit mentioned in Fixes tag. Fixes: bf1299797c3c ("uio_hv_generic: Align ring size to system page") Cc: <stable(a)vger.kernel.org> # 6.12.x Signed-off-by: Naman Jain <namjain(a)linux.microsoft.com> --- This change won't apply on older kernels currently due to missing dependencies. I will take care of them after this goes in. I did not retain any Reviewed-by or Tested-by tags, since the code has changed completely, while the functionality remains same. Requesting Michael, Dexuan, Wei to please review again. --- drivers/hv/vmbus_drv.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c index 1f519e925f06..616e63fb2f15 100644 --- a/drivers/hv/vmbus_drv.c +++ b/drivers/hv/vmbus_drv.c @@ -1810,7 +1810,6 @@ static struct bin_attribute chan_attr_ring_buffer = { .name = "ring", .mode = 0600, }, - .size = 2 * SZ_2M, .mmap = hv_mmap_ring_buffer_wrapper, }; static struct attribute *vmbus_chan_attrs[] = { @@ -1866,6 +1865,7 @@ static umode_t vmbus_chan_bin_attr_is_visible(struct kobject *kobj, /* Hide ring attribute if channel's ring_sysfs_visible is set to false */ if (attr == &chan_attr_ring_buffer && !channel->ring_sysfs_visible) return 0; + attr->size = channel->ringbuffer_pagecount << PAGE_SHIFT; return attr->attr.mode; } -- 2.34.1

1 week, 3 days

3
6
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[PATCH v2] drm: Fix potential null pointer dereference issues in drm_managed.c

by Haoxiang Li

Add check for the return value of kstrdup_const() in drm_managed.c to prevent potential null pointer dereference. Fixes: c6603c740e0e ("drm: add managed resources tied to drm_device") Cc: stable(a)vger.kernel.org Signed-off-by: Haoxiang Li <haoxiang_li2024(a)163.com> --- Changes in v2: - Modify a fix error. Thanks, Dmitry! --- drivers/gpu/drm/drm_managed.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/gpu/drm/drm_managed.c b/drivers/gpu/drm/drm_managed.c index cc4c463daae7..e34b8dcde48c 100644 --- a/drivers/gpu/drm/drm_managed.c +++ b/drivers/gpu/drm/drm_managed.c @@ -151,6 +151,11 @@ int __drmm_add_action(struct drm_device *dev, } dr->node.name = kstrdup_const(name, GFP_KERNEL); + if (!dr->node.name) { + kfree(dr); + return -ENOMEM; + } + if (data) { void_ptr = (void **)&dr->data; *void_ptr = data; @@ -236,6 +241,10 @@ void *drmm_kmalloc(struct drm_device *dev, size_t size, gfp_t gfp) return NULL; } dr->node.name = kstrdup_const("kmalloc", gfp); + if (!dr->node.name) { + kfree(dr); + return NULL; + } add_dr(dev, dr); -- 2.25.1

1 week, 3 days

2
1
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[PATCH v5] mm/slub: avoid accessing metadata when pointer is invalid in object_err()

by Li Qiong

object_err() reports details of an object for further debugging, such as the freelist pointer, redzone, etc. However, if the pointer is invalid, attempting to access object metadata can lead to a crash since it does not point to a valid object. In case check_valid_pointer() returns false for the pointer, only print the pointer value and skip accessing metadata. Fixes: 81819f0fc828 ("SLUB core") Cc: <stable(a)vger.kernel.org> Signed-off-by: Li Qiong <liqiong(a)nfschina.com> --- v2: - rephrase the commit message, add comment for object_err(). v3: - check object pointer in object_err(). v4: - restore changes in alloc_consistency_checks(). v5: - rephrase message, fix code style. --- mm/slub.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/mm/slub.c b/mm/slub.c index 31e11ef256f9..b3eff1476c85 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1104,7 +1104,12 @@ static void object_err(struct kmem_cache *s, struct slab *slab, return; slab_bug(s, reason); - print_trailer(s, slab, object); + if (!check_valid_pointer(s, slab, object)) { + print_slab_info(slab); + pr_err("Invalid pointer 0x%p\n", object); + } else { + print_trailer(s, slab, object); + } add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); WARN_ON(1); -- 2.30.2

1 week, 3 days

3
3
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[PATCH v2] memstick: Fix deadlock by moving removing flag earlier

by Jiayi Li

The existing memstick core patch: commit 62c59a8786e6 ("memstick: Skip allocating card when removing host") sets host->removing in memstick_remove_host(),but still exists a critical time window where memstick_check can run after host->eject is set but before removing is set. In the rtsx_usb_ms driver, the problematic sequence is: rtsx_usb_ms_drv_remove: memstick_check: host->eject = true cancel_work_sync(handle_req) if(!host->removing) ... memstick_alloc_card() memstick_set_rw_addr() memstick_new_req() rtsx_usb_ms_request() if(!host->eject) skip schedule_work wait_for_completion() memstick_remove_host: [blocks indefinitely] host->removing = true flush_workqueue() [block] 1. rtsx_usb_ms_drv_remove sets host->eject = true 2. cancel_work_sync(&host->handle_req) runs 3. memstick_check work may be executed here <-- danger window 4. memstick_remove_host sets removing = 1 During this window (step 3), memstick_check calls memstick_alloc_card, which may indefinitely waiting for mrq_complete completion that will never occur because rtsx_usb_ms_request sees eject=true and skips scheduling work, memstick_set_rw_addr waits forever for completion. This causes a deadlock when memstick_remove_host tries to flush_workqueue, waiting for memstick_check to complete, while memstick_check is blocked waiting for mrq_complete completion. Fix this by setting removing=true at the start of rtsx_usb_ms_drv_remove, before any work cancellation. This ensures memstick_check will see the removing flag immediately and exit early, avoiding the deadlock. Fixes: 62c59a8786e6 ("memstick: Skip allocating card when removing host") Signed-off-by: Jiayi Li <lijiayi(a)kylinos.cn> Cc: stable(a)vger.kernel.org --- v1 -> v2: Added Cc: stable(a)vger.kernel.org --- drivers/memstick/core/memstick.c | 1 - drivers/memstick/host/rtsx_usb_ms.c | 1 + 2 files changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/memstick/core/memstick.c b/drivers/memstick/core/memstick.c index 043b9ec756ff..95e65f4958f2 100644 --- a/drivers/memstick/core/memstick.c +++ b/drivers/memstick/core/memstick.c @@ -555,7 +555,6 @@ EXPORT_SYMBOL(memstick_add_host); */ void memstick_remove_host(struct memstick_host *host) { - host->removing = 1; flush_workqueue(workqueue); mutex_lock(&host->lock); if (host->card) diff --git a/drivers/memstick/host/rtsx_usb_ms.c b/drivers/memstick/host/rtsx_usb_ms.c index 3878136227e4..5b5e9354fb2e 100644 --- a/drivers/memstick/host/rtsx_usb_ms.c +++ b/drivers/memstick/host/rtsx_usb_ms.c @@ -812,6 +812,7 @@ static void rtsx_usb_ms_drv_remove(struct platform_device *pdev) int err; host->eject = true; + msh->removing = true; cancel_work_sync(&host->handle_req); cancel_delayed_work_sync(&host->poll_card); -- 2.47.1

1 week, 3 days

1
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[PATCH v2] memstick: Fix deadlock by moving removing flag earlier

by Jiayi Li

The existing memstick core patch: commit 62c59a8786e6 ("memstick: Skip allocating card when removing host") sets host->removing in memstick_remove_host(),but still exists a critical time window where memstick_check can run after host->eject is set but before removing is set. In the rtsx_usb_ms driver, the problematic sequence is: rtsx_usb_ms_drv_remove: memstick_check: host->eject = true cancel_work_sync(handle_req) if(!host->removing) ... memstick_alloc_card() memstick_set_rw_addr() memstick_new_req() rtsx_usb_ms_request() if(!host->eject) skip schedule_work wait_for_completion() memstick_remove_host: [blocks indefinitely] host->removing = true flush_workqueue() [block] 1. rtsx_usb_ms_drv_remove sets host->eject = true 2. cancel_work_sync(&host->handle_req) runs 3. memstick_check work may be executed here <-- danger window 4. memstick_remove_host sets removing = 1 During this window (step 3), memstick_check calls memstick_alloc_card, which may indefinitely waiting for mrq_complete completion that will never occur because rtsx_usb_ms_request sees eject=true and skips scheduling work, memstick_set_rw_addr waits forever for completion. This causes a deadlock when memstick_remove_host tries to flush_workqueue, waiting for memstick_check to complete, while memstick_check is blocked waiting for mrq_complete completion. Fix this by setting removing=true at the start of rtsx_usb_ms_drv_remove, before any work cancellation. This ensures memstick_check will see the removing flag immediately and exit early, avoiding the deadlock. Fixes: 62c59a8786e6 ("memstick: Skip allocating card when removing host") Signed-off-by: Jiayi Li <lijiayi(a)kylinos.cn> Cc: stable(a)vger.kernel.org --- v1 -> v2: Added Cc: stable(a)vger.kernel.org --- drivers/memstick/core/memstick.c | 1 - drivers/memstick/host/rtsx_usb_ms.c | 1 + 2 files changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/memstick/core/memstick.c b/drivers/memstick/core/memstick.c index 043b9ec756ff..95e65f4958f2 100644 --- a/drivers/memstick/core/memstick.c +++ b/drivers/memstick/core/memstick.c @@ -555,7 +555,6 @@ EXPORT_SYMBOL(memstick_add_host); */ void memstick_remove_host(struct memstick_host *host) { - host->removing = 1; flush_workqueue(workqueue); mutex_lock(&host->lock); if (host->card) diff --git a/drivers/memstick/host/rtsx_usb_ms.c b/drivers/memstick/host/rtsx_usb_ms.c index 3878136227e4..5b5e9354fb2e 100644 --- a/drivers/memstick/host/rtsx_usb_ms.c +++ b/drivers/memstick/host/rtsx_usb_ms.c @@ -812,6 +812,7 @@ static void rtsx_usb_ms_drv_remove(struct platform_device *pdev) int err; host->eject = true; + msh->removing = true; cancel_work_sync(&host->handle_req); cancel_delayed_work_sync(&host->poll_card); -- 2.47.1

1 week, 3 days

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[PATCH AUTOSEL 5.4 01/28] usb: xhci: print xhci->xhc_state when queue_command failed

by Sasha Levin

From: Su Hui <suhui(a)nfschina.com> [ Upstream commit 7919407eca2ef562fa6c98c41cfdf6f6cdd69d92 ] When encounters some errors like these: xhci_hcd 0000:4a:00.2: xHCI dying or halted, can't queue_command xhci_hcd 0000:4a:00.2: FIXME: allocate a command ring segment usb usb5-port6: couldn't allocate usb_device It's hard to know whether xhc_state is dying or halted. So it's better to print xhc_state's value which can help locate the resaon of the bug. Signed-off-by: Su Hui <suhui(a)nfschina.com> Link: https://lore.kernel.org/r/20250725060117.1773770-1-suhui@nfschina.com Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Signed-off-by: Sasha Levin <sashal(a)kernel.org> --- LLM Generated explanations, may be completely bogus: **Backport Status: YES** This commit is suitable for backporting to stable kernel trees for the following reasons: 1. **Enhanced Debugging for Real-World Issues**: The commit improves debugging of USB xHCI host controller failures by printing the actual `xhc_state` value when `queue_command` fails. The commit message shows real error messages users encounter ("xHCI dying or halted, can't queue_command"), demonstrating this is a real-world debugging problem. 2. **Minimal and Safe Change**: The change is extremely small and safe - it only modifies a debug print statement from: ```c xhci_dbg(xhci, "xHCI dying or halted, can't queue_command\n"); ``` to: ```c xhci_dbg(xhci, "xHCI dying or halted, can't queue_command. state: 0x%x\n", xhci->xhc_state); ``` 3. **No Functional Changes**: This is a pure diagnostic improvement. It doesn't change any logic, control flow, or data structures. It only adds the state value (0x%x format) to an existing debug message. 4. **Important for Troubleshooting**: The xHCI driver is critical for USB functionality, and when it fails with "dying or halted" states, knowing the exact state helps diagnose whether: - `XHCI_STATE_DYING` (0x1) - controller is dying - `XHCI_STATE_HALTED` (0x2) - controller is halted - Both states (0x3) - controller has both flags set This distinction is valuable for debugging hardware issues, driver bugs, or system problems. 5. **Zero Risk of Regression**: Adding a parameter to a debug print statement has no risk of introducing regressions. The worst case is the debug message prints the state value. 6. **Follows Stable Rules**: This meets stable kernel criteria as it: - Fixes a real debugging limitation - Is obviously correct - Has been tested (signed-off and accepted by Greg KH) - Is small (single line change) - Doesn't add new features, just improves existing diagnostics The commit helps system administrators and developers diagnose USB issues more effectively by providing the actual state value rather than just saying "dying or halted", making it a valuable debugging enhancement for stable kernels. drivers/usb/host/xhci-ring.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index 08b016864fc0..71b17a00d3ed 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -4076,7 +4076,8 @@ static int queue_command(struct xhci_hcd *xhci, struct xhci_command *cmd, if ((xhci->xhc_state & XHCI_STATE_DYING) || (xhci->xhc_state & XHCI_STATE_HALTED)) { - xhci_dbg(xhci, "xHCI dying or halted, can't queue_command\n"); + xhci_dbg(xhci, "xHCI dying or halted, can't queue_command. state: 0x%x\n", + xhci->xhc_state); return -ESHUTDOWN; } -- 2.39.5

1 week, 3 days

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[PATCH AUTOSEL 5.10 01/39] usb: xhci: print xhci->xhc_state when queue_command failed

by Sasha Levin

From: Su Hui <suhui(a)nfschina.com> [ Upstream commit 7919407eca2ef562fa6c98c41cfdf6f6cdd69d92 ] When encounters some errors like these: xhci_hcd 0000:4a:00.2: xHCI dying or halted, can't queue_command xhci_hcd 0000:4a:00.2: FIXME: allocate a command ring segment usb usb5-port6: couldn't allocate usb_device It's hard to know whether xhc_state is dying or halted. So it's better to print xhc_state's value which can help locate the resaon of the bug. Signed-off-by: Su Hui <suhui(a)nfschina.com> Link: https://lore.kernel.org/r/20250725060117.1773770-1-suhui@nfschina.com Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Signed-off-by: Sasha Levin <sashal(a)kernel.org> --- LLM Generated explanations, may be completely bogus: **Backport Status: YES** This commit is suitable for backporting to stable kernel trees for the following reasons: 1. **Enhanced Debugging for Real-World Issues**: The commit improves debugging of USB xHCI host controller failures by printing the actual `xhc_state` value when `queue_command` fails. The commit message shows real error messages users encounter ("xHCI dying or halted, can't queue_command"), demonstrating this is a real-world debugging problem. 2. **Minimal and Safe Change**: The change is extremely small and safe - it only modifies a debug print statement from: ```c xhci_dbg(xhci, "xHCI dying or halted, can't queue_command\n"); ``` to: ```c xhci_dbg(xhci, "xHCI dying or halted, can't queue_command. state: 0x%x\n", xhci->xhc_state); ``` 3. **No Functional Changes**: This is a pure diagnostic improvement. It doesn't change any logic, control flow, or data structures. It only adds the state value (0x%x format) to an existing debug message. 4. **Important for Troubleshooting**: The xHCI driver is critical for USB functionality, and when it fails with "dying or halted" states, knowing the exact state helps diagnose whether: - `XHCI_STATE_DYING` (0x1) - controller is dying - `XHCI_STATE_HALTED` (0x2) - controller is halted - Both states (0x3) - controller has both flags set This distinction is valuable for debugging hardware issues, driver bugs, or system problems. 5. **Zero Risk of Regression**: Adding a parameter to a debug print statement has no risk of introducing regressions. The worst case is the debug message prints the state value. 6. **Follows Stable Rules**: This meets stable kernel criteria as it: - Fixes a real debugging limitation - Is obviously correct - Has been tested (signed-off and accepted by Greg KH) - Is small (single line change) - Doesn't add new features, just improves existing diagnostics The commit helps system administrators and developers diagnose USB issues more effectively by providing the actual state value rather than just saying "dying or halted", making it a valuable debugging enhancement for stable kernels. drivers/usb/host/xhci-ring.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index 954cd962e113..c026e7cc0af1 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -4183,7 +4183,8 @@ static int queue_command(struct xhci_hcd *xhci, struct xhci_command *cmd, if ((xhci->xhc_state & XHCI_STATE_DYING) || (xhci->xhc_state & XHCI_STATE_HALTED)) { - xhci_dbg(xhci, "xHCI dying or halted, can't queue_command\n"); + xhci_dbg(xhci, "xHCI dying or halted, can't queue_command. state: 0x%x\n", + xhci->xhc_state); return -ESHUTDOWN; } -- 2.39.5

1 week, 3 days

1
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[PATCH AUTOSEL 5.15 01/44] usb: xhci: print xhci->xhc_state when queue_command failed

by Sasha Levin

From: Su Hui <suhui(a)nfschina.com> [ Upstream commit 7919407eca2ef562fa6c98c41cfdf6f6cdd69d92 ] When encounters some errors like these: xhci_hcd 0000:4a:00.2: xHCI dying or halted, can't queue_command xhci_hcd 0000:4a:00.2: FIXME: allocate a command ring segment usb usb5-port6: couldn't allocate usb_device It's hard to know whether xhc_state is dying or halted. So it's better to print xhc_state's value which can help locate the resaon of the bug. Signed-off-by: Su Hui <suhui(a)nfschina.com> Link: https://lore.kernel.org/r/20250725060117.1773770-1-suhui@nfschina.com Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Signed-off-by: Sasha Levin <sashal(a)kernel.org> --- LLM Generated explanations, may be completely bogus: **Backport Status: YES** This commit is suitable for backporting to stable kernel trees for the following reasons: 1. **Enhanced Debugging for Real-World Issues**: The commit improves debugging of USB xHCI host controller failures by printing the actual `xhc_state` value when `queue_command` fails. The commit message shows real error messages users encounter ("xHCI dying or halted, can't queue_command"), demonstrating this is a real-world debugging problem. 2. **Minimal and Safe Change**: The change is extremely small and safe - it only modifies a debug print statement from: ```c xhci_dbg(xhci, "xHCI dying or halted, can't queue_command\n"); ``` to: ```c xhci_dbg(xhci, "xHCI dying or halted, can't queue_command. state: 0x%x\n", xhci->xhc_state); ``` 3. **No Functional Changes**: This is a pure diagnostic improvement. It doesn't change any logic, control flow, or data structures. It only adds the state value (0x%x format) to an existing debug message. 4. **Important for Troubleshooting**: The xHCI driver is critical for USB functionality, and when it fails with "dying or halted" states, knowing the exact state helps diagnose whether: - `XHCI_STATE_DYING` (0x1) - controller is dying - `XHCI_STATE_HALTED` (0x2) - controller is halted - Both states (0x3) - controller has both flags set This distinction is valuable for debugging hardware issues, driver bugs, or system problems. 5. **Zero Risk of Regression**: Adding a parameter to a debug print statement has no risk of introducing regressions. The worst case is the debug message prints the state value. 6. **Follows Stable Rules**: This meets stable kernel criteria as it: - Fixes a real debugging limitation - Is obviously correct - Has been tested (signed-off and accepted by Greg KH) - Is small (single line change) - Doesn't add new features, just improves existing diagnostics The commit helps system administrators and developers diagnose USB issues more effectively by providing the actual state value rather than just saying "dying or halted", making it a valuable debugging enhancement for stable kernels. drivers/usb/host/xhci-ring.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index cd94b0a4e021..626f02605192 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -4486,7 +4486,8 @@ static int queue_command(struct xhci_hcd *xhci, struct xhci_command *cmd, if ((xhci->xhc_state & XHCI_STATE_DYING) || (xhci->xhc_state & XHCI_STATE_HALTED)) { - xhci_dbg(xhci, "xHCI dying or halted, can't queue_command\n"); + xhci_dbg(xhci, "xHCI dying or halted, can't queue_command. state: 0x%x\n", + xhci->xhc_state); return -ESHUTDOWN; } -- 2.39.5

1 week, 3 days

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[PATCH v4] mm: slub: avoid deref of invalid free pointer in object_err()

by Li Qiong

For debugging, object_err() prints free pointer of the object. However, if object is a invalid pointer, dereferncing `object + s->offset` can lead to a crash. Therefore, add check_valid_pointer() for the object. Fixes: 81819f0fc828 ("SLUB core") Cc: <stable(a)vger.kernel.org> Signed-off-by: Li Qiong <liqiong(a)nfschina.com> --- v2: - rephrase the commit message, add comment for object_err(). v3: - check object pointer in object_err(). v4: - restore changes in alloc_consistency_checks(). --- mm/slub.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/mm/slub.c b/mm/slub.c index 31e11ef256f9..17b91e74f7d9 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1104,7 +1104,11 @@ static void object_err(struct kmem_cache *s, struct slab *slab, return; slab_bug(s, reason); - print_trailer(s, slab, object); + if (!check_valid_pointer(s, slab, object)) { + print_slab_info(slab); + pr_err("invalid object 0x%p\n", object); + } else + print_trailer(s, slab, object); add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); WARN_ON(1); -- 2.30.2

1 week, 3 days

2
1
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[PATCH AUTOSEL 6.12 01/69] usb: xhci: print xhci->xhc_state when queue_command failed

by Sasha Levin

From: Su Hui <suhui(a)nfschina.com> [ Upstream commit 7919407eca2ef562fa6c98c41cfdf6f6cdd69d92 ] When encounters some errors like these: xhci_hcd 0000:4a:00.2: xHCI dying or halted, can't queue_command xhci_hcd 0000:4a:00.2: FIXME: allocate a command ring segment usb usb5-port6: couldn't allocate usb_device It's hard to know whether xhc_state is dying or halted. So it's better to print xhc_state's value which can help locate the resaon of the bug. Signed-off-by: Su Hui <suhui(a)nfschina.com> Link: https://lore.kernel.org/r/20250725060117.1773770-1-suhui@nfschina.com Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Signed-off-by: Sasha Levin <sashal(a)kernel.org> --- LLM Generated explanations, may be completely bogus: **Backport Status: YES** This commit is suitable for backporting to stable kernel trees for the following reasons: 1. **Enhanced Debugging for Real-World Issues**: The commit improves debugging of USB xHCI host controller failures by printing the actual `xhc_state` value when `queue_command` fails. The commit message shows real error messages users encounter ("xHCI dying or halted, can't queue_command"), demonstrating this is a real-world debugging problem. 2. **Minimal and Safe Change**: The change is extremely small and safe - it only modifies a debug print statement from: ```c xhci_dbg(xhci, "xHCI dying or halted, can't queue_command\n"); ``` to: ```c xhci_dbg(xhci, "xHCI dying or halted, can't queue_command. state: 0x%x\n", xhci->xhc_state); ``` 3. **No Functional Changes**: This is a pure diagnostic improvement. It doesn't change any logic, control flow, or data structures. It only adds the state value (0x%x format) to an existing debug message. 4. **Important for Troubleshooting**: The xHCI driver is critical for USB functionality, and when it fails with "dying or halted" states, knowing the exact state helps diagnose whether: - `XHCI_STATE_DYING` (0x1) - controller is dying - `XHCI_STATE_HALTED` (0x2) - controller is halted - Both states (0x3) - controller has both flags set This distinction is valuable for debugging hardware issues, driver bugs, or system problems. 5. **Zero Risk of Regression**: Adding a parameter to a debug print statement has no risk of introducing regressions. The worst case is the debug message prints the state value. 6. **Follows Stable Rules**: This meets stable kernel criteria as it: - Fixes a real debugging limitation - Is obviously correct - Has been tested (signed-off and accepted by Greg KH) - Is small (single line change) - Doesn't add new features, just improves existing diagnostics The commit helps system administrators and developers diagnose USB issues more effectively by providing the actual state value rather than just saying "dying or halted", making it a valuable debugging enhancement for stable kernels. drivers/usb/host/xhci-ring.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index 2ff8787f753c..19978f02bb9e 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -4378,7 +4378,8 @@ static int queue_command(struct xhci_hcd *xhci, struct xhci_command *cmd, if ((xhci->xhc_state & XHCI_STATE_DYING) || (xhci->xhc_state & XHCI_STATE_HALTED)) { - xhci_dbg(xhci, "xHCI dying or halted, can't queue_command\n"); + xhci_dbg(xhci, "xHCI dying or halted, can't queue_command. state: 0x%x\n", + xhci->xhc_state); return -ESHUTDOWN; } -- 2.39.5

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Linux-stable-mirror August 2025