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* [PATCH] drm/xe: Kill missing outer runtime PM protection warning
@ 2024-09-03 22:38 Rodrigo Vivi
  2024-09-03 23:25 ` ✓ CI.Patch_applied: success for " Patchwork
                   ` (8 more replies)
  0 siblings, 9 replies; 14+ messages in thread
From: Rodrigo Vivi @ 2024-09-03 22:38 UTC (permalink / raw)
  To: intel-xe; +Cc: Rodrigo Vivi, Matthew Brost, Matthew Auld, Thomas Hellström

This message was very useful to ensure that Xe was taking all
the needed outer runtime pm references. However, at this point
it is only a false positive. So, remove it.

False positive cases:

1:
[184.983389] xe ...: [drm] Missing outer runtime PM protection
[snip]
[184.984096]  drm_ioctl+0x2cf/0x580 [drm]
[snip]
[184.984710] xe 0000:00:02.0: Runtime PM usage count underflow!

In this case the underflow is the problem since we are sure that
the ioctl is protected. But something else is abusing the 'put'
calls.

2:
rpm_status:           0000:03:00.0 status=RPM_SUSPENDING
console:              xe_bo_evict_all (called from suspend)
xe_sched_job_create:  dev=0000:03:00.0, ...
xe_sched_job_exec:    dev=0000:03:00.0, ...
xe_pm_runtime_put:    dev=0000:03:00.0, ...
xe_sched_job_run:     dev=0000:03:00.0, ...
rpm_usage:            0000:03:00.0 flags-0 cnt-2  ...
rpm_usage:            0000:03:00.0 flags-0 cnt-2  ...
rpm_usage:            0000:03:00.0 flags-0 cnt-2  ...
console:              xe 0000:03:00.0: [drm] Missing outer runtime
		      	 	       	     	     PM protection
console:               xe_guc_ct_send+0x15/0x50 [xe]
console:               guc_exec_queue_run_job+0x1509/0x3950 [xe]
[snip]
console:               drm_sched_run_job_work+0x649/0xc20

At this point, BOs are getting evicted from VRAM with rpm
usage-counter = 2, but rpm status = SUSPENDING.
The xe->pm_callback_task won't be equal 'current' because this call is
coming from a work queue.

So, pm_runtime_get_if_active() will be called and return 0 because rpm
status != ACTIVE (but equal SUSPENDING).

The only way out is to just grab the reference and move on.

Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
---
 drivers/gpu/drm/xe/xe_pm.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_pm.c b/drivers/gpu/drm/xe/xe_pm.c
index da68cd689a96..e1a5e43b0f34 100644
--- a/drivers/gpu/drm/xe/xe_pm.c
+++ b/drivers/gpu/drm/xe/xe_pm.c
@@ -592,20 +592,14 @@ bool xe_pm_runtime_get_if_in_use(struct xe_device *xe)
  * xe_pm_runtime_get_noresume - Bump runtime PM usage counter without resuming
  * @xe: xe device instance
  *
- * This function should be used in inner places where it is surely already
+ * This function should *only* be used in inner places where it is surely already
  * protected by outer-bound callers of `xe_pm_runtime_get`.
- * It will warn if not protected.
  * The reference should be put back after this function regardless, since it
  * will always bump the usage counter, regardless.
  */
 void xe_pm_runtime_get_noresume(struct xe_device *xe)
 {
-	bool ref;
-
-	ref = xe_pm_runtime_get_if_in_use(xe);
-
-	if (drm_WARN(&xe->drm, !ref, "Missing outer runtime PM protection\n"))
-		pm_runtime_get_noresume(xe->drm.dev);
+	pm_runtime_get_noresume(xe->drm.dev);
 }
 
 /**
-- 
2.46.0


^ permalink raw reply related	[flat|nested] 14+ messages in thread
end of thread, other threads:[~2024-09-04 16:07 UTC | newest]

Thread overview: 14+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2024-09-03 22:38 [PATCH] drm/xe: Kill missing outer runtime PM protection warning Rodrigo Vivi
2024-09-03 23:25 ` ✓ CI.Patch_applied: success for " Patchwork
2024-09-03 23:25 ` ✓ CI.checkpatch: " Patchwork
2024-09-03 23:26 ` ✓ CI.KUnit: " Patchwork
2024-09-03 23:38 ` ✓ CI.Build: " Patchwork
2024-09-03 23:40 ` ✓ CI.Hooks: " Patchwork
2024-09-03 23:41 ` ✓ CI.checksparse: " Patchwork
2024-09-04  0:00 ` ✓ CI.BAT: " Patchwork
2024-09-04  4:19 ` ✗ CI.FULL: failure " Patchwork
2024-09-04 12:49 ` [PATCH] " Matthew Auld
2024-09-04 14:53   ` Matthew Brost
2024-09-04 15:03   ` Rodrigo Vivi
2024-09-04 15:42     ` Matthew Auld
2024-09-04 16:06       ` Rodrigo Vivi

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