[PATCH 6.1 186/236] Reapply "drm/qxl: simplify qxl_fence_wait"

Greg Kroah-Hartman
2024-05-14T11:37:48Z

From: Linus Torvalds <torvalds@linux-foundation.org>

commit 3628e0383dd349f02f882e612ab6184e4bb3dc10 upstream.

This reverts commit 07ed11afb68d94eadd4ffc082b97c2331307c5ea.

Stephen Rostedt reports:
"I went to run my tests on my VMs and the tests hung on boot up.
Unfortunately, the most I ever got out was:

[ 93.607888] Testing event system initcall: OK
[ 93.667730] Running tests on all trace events:
[ 93.669757] Testing all events: OK
[ 95.631064] ------------[ cut here ]------------
Timed out after 60 seconds"

and further debugging points to a possible circular locking dependency
between the console_owner locking and the worker pool locking.

Reverting the commit allows Steve's VM to boot to completion again.

[ This may obviously result in the "[TTM] Buffer eviction failed"
messages again, which was the reason for that original revert. But at
this point this seems preferable to a non-booting system... ]

Reported-and-bisected-by: Steven Rostedt <rostedt@goodmis.org>
Link: https://lore.kernel.org/all/20240502081641.457aa25f@gandalf.local.home/
Acked-by: Maxime Ripard <mripard@kernel.org>
Cc: Alex Constantino <dreaming.about.electric.sheep@gmail.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Timo Lindfors <timo.lindfors@iki.fi>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/gpu/drm/qxl/qxl_release.c | 50 +++-----------------------------------
include/linux/dma-fence.h | 7 -----
2 files changed, 5 insertions(+), 52 deletions(-)

--- a/drivers/gpu/drm/qxl/qxl_release.c
+++ b/drivers/gpu/drm/qxl/qxl_release.c
@@ -58,56 +58,16 @@ static long qxl_fence_wait(struct dma_fe
signed long timeout)
{
struct qxl_device *qdev;
- struct qxl_release *release;
- int count = 0, sc = 0;
- bool have_drawable_releases;
unsigned long cur, end = jiffies + timeout;

qdev = container_of(fence->lock, struct qxl_device, release_lock);
- release = container_of(fence, struct qxl_release, base);
- have_drawable_releases = release->type == QXL_RELEASE_DRAWABLE;

-retry:
- sc++;
-
- if (dma_fence_is_signaled(fence))
- goto signaled;
-
- qxl_io_notify_oom(qdev);
-
- for (count = 0; count < 11; count++) {
- if (!qxl_queue_garbage_collect(qdev, true))
- break;
-
- if (dma_fence_is_signaled(fence))
- goto signaled;
- }
-
- if (dma_fence_is_signaled(fence))
- goto signaled;
-
- if (have_drawable_releases || sc < 4) {
- if (sc > 2)
- /* back off */
- usleep_range(500, 1000);
-
- if (time_after(jiffies, end))
- return 0;
-
- if (have_drawable_releases && sc > 300) {
- DMA_FENCE_WARN(fence,
- "failed to wait on release %llu after spincount %d\n",
- fence->context & ~0xf0000000, sc);
- goto signaled;
- }
- goto retry;
- }
- /*
- * yeah, original sync_obj_wait gave up after 3 spins when
- * have_drawable_releases is not set.
- */
+ if (!wait_event_timeout(qdev->release_event,
+ (dma_fence_is_signaled(fence) ||
+ (qxl_io_notify_oom(qdev), 0)),
+ timeout))
+ return 0;

-signaled:
cur = jiffies;
if (time_after(cur, end))
return 0;
--- a/include/linux/dma-fence.h
+++ b/include/linux/dma-fence.h
@@ -659,11 +659,4 @@ static inline bool dma_fence_is_containe
return dma_fence_is_array(fence) || dma_fence_is_chain(fence);
}

-#define DMA_FENCE_WARN(f, fmt, args...) \
- do { \
- struct dma_fence *__ff = (f); \
- pr_warn("f %llu#%llu: " fmt, __ff->context, __ff->seqno,\
- ##args); \
- } while (0)
-
#endif /* __LINUX_DMA_FENCE_H */