From: Brendan King <Brendan.King@xxxxxxxxxx>
Do scheduler queue fence release processing on a workqueue, rather
than in the release function itself.
Fixes deadlock issues such as the following:
[ 607.400437] ============================================
[ 607.405755] WARNING: possible recursive locking detected
[ 607.415500] --------------------------------------------
[ 607.420817] weston:zfq0/24149 is trying to acquire lock:
[ 607.426131] ffff000017d041a0 (reservation_ww_class_mutex){+.+.}-{3:3}, at: pvr_gem_object_vunmap+0x40/0xc0 [powervr]
[ 607.436728]
but task is already holding lock:
[ 607.442554] ffff000017d105a0 (reservation_ww_class_mutex){+.+.}-{3:3}, at: dma_buf_ioctl+0x250/0x554
[ 607.451727]
other info that might help us debug this:
[ 607.458245] Possible unsafe locking scenario:
[ 607.464155] CPU0
[ 607.466601] ----
[ 607.469044] lock(reservation_ww_class_mutex);
[ 607.473584] lock(reservation_ww_class_mutex);
[ 607.478114]
*** DEADLOCK ***
Signed-off-by: Brendan King <brendan.king@xxxxxxxxxx>
---
drivers/gpu/drm/imagination/pvr_queue.c | 13 +++++++++++--
drivers/gpu/drm/imagination/pvr_queue.h | 4 ++++
2 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/imagination/pvr_queue.c b/drivers/gpu/drm/imagination/pvr_queue.c
index c4f08432882b12f5cdfeb7fc991fd941f0946676..f3f1c5212df7432161919ddc510cececacbbe143 100644
--- a/drivers/gpu/drm/imagination/pvr_queue.c
+++ b/drivers/gpu/drm/imagination/pvr_queue.c
@@ -109,12 +109,20 @@ pvr_queue_fence_get_driver_name(struct dma_fence *f)
return PVR_DRIVER_NAME;
}
+static void pvr_queue_fence_release_work(struct work_struct *w)
+{
+ struct pvr_queue_fence *fence = container_of(w, struct pvr_queue_fence, release_work);
+
+ pvr_context_put(fence->queue->ctx);
+ dma_fence_free(&fence->base);
+}
+
static void pvr_queue_fence_release(struct dma_fence *f)
{
struct pvr_queue_fence *fence = container_of(f, struct pvr_queue_fence, base);
+ struct pvr_device *pvr_dev = fence->queue->ctx->pvr_dev;
- pvr_context_put(fence->queue->ctx);
- dma_fence_free(f);
+ queue_work(pvr_dev->sched_wq, &fence->release_work);
}
static const char *
@@ -268,6 +276,7 @@ pvr_queue_fence_init(struct dma_fence *f,
pvr_context_get(queue->ctx);
fence->queue = queue;
+ INIT_WORK(&fence->release_work, pvr_queue_fence_release_work);
dma_fence_init(&fence->base, fence_ops,
&fence_ctx->lock, fence_ctx->id,
atomic_inc_return(&fence_ctx->seqno));
diff --git a/drivers/gpu/drm/imagination/pvr_queue.h b/drivers/gpu/drm/imagination/pvr_queue.h
index e06ced69302fca47fc26451dfb09ebbb24b57f52..93fe9ac9f58ccc020615485e86be438548dcee43 100644
--- a/drivers/gpu/drm/imagination/pvr_queue.h
+++ b/drivers/gpu/drm/imagination/pvr_queue.h
@@ -5,6 +5,7 @@
#define PVR_QUEUE_H
#include <drm/gpu_scheduler.h>
+#include <linux/workqueue.h>
#include "pvr_cccb.h"
#include "pvr_device.h"
@@ -63,6 +64,9 @@ struct pvr_queue_fence {
/** @queue: Queue that created this fence. */
struct pvr_queue *queue;
+
+ /** @release_work: Fence release work structure. */
+ struct work_struct release_work;
};
/**
---
base-commit: 3ab334814dc7dff39075e055e12847d51878916e
change-id: 20250203-fence-release-deadlock-a0753c07bfdd
Best regards,
--
Brendan King <Brendan.King@xxxxxxxxxx>
