[PATCH v3] drm/amdgpu: change reset lock from mutex to rw_semaphore

Liu, Monk Monk.Liu at amd.com
Fri Aug 21 06:10:09 UTC 2020


[AMD Official Use Only - Internal Distribution Only]

Reviewed-by: Monk Liu <monk.liu at amd.com>

_____________________________________
Monk Liu|GPU Virtualization Team |AMD


-----Original Message-----
From: Dennis Li <Dennis.Li at amd.com>
Sent: Friday, August 21, 2020 11:48 AM
To: amd-gfx at lists.freedesktop.org; Deucher, Alexander <Alexander.Deucher at amd.com>; Kuehling, Felix <Felix.Kuehling at amd.com>; Zhang, Hawking <Hawking.Zhang at amd.com>; Koenig, Christian <Christian.Koenig at amd.com>; Liu, Monk <Monk.Liu at amd.com>
Cc: Li, Dennis <Dennis.Li at amd.com>
Subject: [PATCH v3] drm/amdgpu: change reset lock from mutex to rw_semaphore

clients don't need reset-lock for synchronization when no GPU recovery.

v2:
change to return the return value of down_read_killable.

v3:
if GPU recovery begin, VF ignore FLR notification.

Signed-off-by: Dennis Li <Dennis.Li at amd.com>

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index c8aec832b244..ec11ed2a9ca4 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -954,7 +954,7 @@ struct amdgpu_device {

 atomic_t in_gpu_reset;
 enum pp_mp1_state               mp1_state;
-struct mutex  lock_reset;
+struct rw_semaphore reset_sem;
 struct amdgpu_doorbell_index doorbell_index;

 struct mutexnotifier_lock;
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
index 79b397800cbc..cc5c7f81c540 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
@@ -101,14 +101,18 @@ static int amdgpu_debugfs_autodump_open(struct inode *inode, struct file *file)

 file->private_data = adev;

-mutex_lock(&adev->lock_reset);
+ret = down_read_killable(&adev->reset_sem);
+if (ret)
+return ret;
+
 if (adev->autodump.dumping.done) {
 reinit_completion(&adev->autodump.dumping);
 ret = 0;
 } else {
 ret = -EBUSY;
 }
-mutex_unlock(&adev->lock_reset);
+
+up_read(&adev->reset_sem);

 return ret;
 }
@@ -1242,7 +1246,9 @@ static int amdgpu_debugfs_test_ib(struct seq_file *m, void *data)
 }

 /* Avoid accidently unparking the sched thread during GPU reset */
-mutex_lock(&adev->lock_reset);
+r = down_read_killable(&adev->reset_sem);
+if (r)
+return r;

 /* hold on the scheduler */
 for (i = 0; i < AMDGPU_MAX_RINGS; i++) { @@ -1269,7 +1275,7 @@ static int amdgpu_debugfs_test_ib(struct seq_file *m, void *data)
 kthread_unpark(ring->sched.thread);
 }

-mutex_unlock(&adev->lock_reset);
+up_read(&adev->reset_sem);

 pm_runtime_mark_last_busy(dev->dev);
 pm_runtime_put_autosuspend(dev->dev);
@@ -1459,7 +1465,9 @@ static int amdgpu_debugfs_ib_preempt(void *data, u64 val)
 return -ENOMEM;

 /* Avoid accidently unparking the sched thread during GPU reset */
-mutex_lock(&adev->lock_reset);
+r = down_read_killable(&adev->reset_sem);
+if (r)
+goto pro_end;

 /* stop the scheduler */
 kthread_park(ring->sched.thread);
@@ -1500,13 +1508,14 @@ static int amdgpu_debugfs_ib_preempt(void *data, u64 val)
 /* restart the scheduler */
 kthread_unpark(ring->sched.thread);

-mutex_unlock(&adev->lock_reset);
+up_read(&adev->reset_sem);

 ttm_bo_unlock_delayed_workqueue(&adev->mman.bdev, resched);

+pro_end:
 kfree(fences);

-return 0;
+return r;
 }

 static int amdgpu_debugfs_sclk_set(void *data, u64 val) diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index 78fd2c9a7b7d..82242e2f5658 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -3054,7 +3054,7 @@ int amdgpu_device_init(struct amdgpu_device *adev,
 mutex_init(&adev->virt.vf_errors.lock);
 hash_init(adev->mn_hash);
 atomic_set(&adev->in_gpu_reset, 0);
-mutex_init(&adev->lock_reset);
+init_rwsem(&adev->reset_sem);
 mutex_init(&adev->psp.mutex);
 mutex_init(&adev->notifier_lock);

@@ -4206,7 +4206,7 @@ static bool amdgpu_device_lock_adev(struct amdgpu_device *adev)
 if (atomic_cmpxchg(&adev->in_gpu_reset, 0, 1) != 0)
 return false;

-mutex_lock(&adev->lock_reset);
+down_write(&adev->reset_sem);

 atomic_inc(&adev->gpu_reset_counter);
 switch (amdgpu_asic_reset_method(adev)) { @@ -4229,7 +4229,7 @@ static void amdgpu_device_unlock_adev(struct amdgpu_device *adev)
 amdgpu_vf_error_trans_all(adev);
 adev->mp1_state = PP_MP1_STATE_NONE;
 atomic_set(&adev->in_gpu_reset, 0);
-mutex_unlock(&adev->lock_reset);
+up_write(&adev->reset_sem);
 }

 static void amdgpu_device_resume_display_audio(struct amdgpu_device *adev) diff --git a/drivers/gpu/drm/amd/amdgpu/mxgpu_ai.c b/drivers/gpu/drm/amd/amdgpu/mxgpu_ai.c
index f27d83f2de78..9c07014d9bd6 100644
--- a/drivers/gpu/drm/amd/amdgpu/mxgpu_ai.c
+++ b/drivers/gpu/drm/amd/amdgpu/mxgpu_ai.c
@@ -238,19 +238,15 @@ static void xgpu_ai_mailbox_flr_work(struct work_struct *work)
 struct amdgpu_virt *virt = container_of(work, struct amdgpu_virt, flr_work);
 struct amdgpu_device *adev = container_of(virt, struct amdgpu_device, virt);
 int timeout = AI_MAILBOX_POLL_FLR_TIMEDOUT;
-int locked;

 /* block amdgpu_gpu_recover till msg FLR COMPLETE received,
  * otherwise the mailbox msg will be ruined/reseted by
  * the VF FLR.
- *
- * we can unlock the lock_reset to allow "amdgpu_job_timedout"
- * to run gpu_recover() after FLR_NOTIFICATION_CMPL received
- * which means host side had finished this VF's FLR.
  */
-locked = mutex_trylock(&adev->lock_reset);
-if (locked)
-atomic_set(&adev->in_gpu_reset, 1);
+if (!down_read_trylock(&adev->reset_sem))
+return;
+
+atomic_set(&adev->in_gpu_reset, 1);

 do {
 if (xgpu_ai_mailbox_peek_msg(adev) == IDH_FLR_NOTIFICATION_CMPL) @@ -261,10 +257,8 @@ static void xgpu_ai_mailbox_flr_work(struct work_struct *work)
 } while (timeout > 1);

 flr_done:
-if (locked) {
-atomic_set(&adev->in_gpu_reset, 0);
-mutex_unlock(&adev->lock_reset);
-}
+atomic_set(&adev->in_gpu_reset, 0);
+up_read(&adev->reset_sem);

 /* Trigger recovery for world switch failure if no TDR */
 if (amdgpu_device_should_recover_gpu(adev)
diff --git a/drivers/gpu/drm/amd/amdgpu/mxgpu_nv.c b/drivers/gpu/drm/amd/amdgpu/mxgpu_nv.c
index 3cb10ab943a6..9c23abf9b140 100644
--- a/drivers/gpu/drm/amd/amdgpu/mxgpu_nv.c
+++ b/drivers/gpu/drm/amd/amdgpu/mxgpu_nv.c
@@ -259,19 +259,15 @@ static void xgpu_nv_mailbox_flr_work(struct work_struct *work)
 struct amdgpu_virt *virt = container_of(work, struct amdgpu_virt, flr_work);
 struct amdgpu_device *adev = container_of(virt, struct amdgpu_device, virt);
 int timeout = NV_MAILBOX_POLL_FLR_TIMEDOUT;
-int locked;

 /* block amdgpu_gpu_recover till msg FLR COMPLETE received,
  * otherwise the mailbox msg will be ruined/reseted by
  * the VF FLR.
- *
- * we can unlock the lock_reset to allow "amdgpu_job_timedout"
- * to run gpu_recover() after FLR_NOTIFICATION_CMPL received
- * which means host side had finished this VF's FLR.
  */
-locked = mutex_trylock(&adev->lock_reset);
-if (locked)
-atomic_set(&adev->in_gpu_reset, 1);
+if (!down_read_trylock(&adev->reset_sem))
+return;
+
+atomic_set(&adev->in_gpu_reset, 1);

 do {
 if (xgpu_nv_mailbox_peek_msg(adev) == IDH_FLR_NOTIFICATION_CMPL) @@ -282,10 +278,8 @@ static void xgpu_nv_mailbox_flr_work(struct work_struct *work)
 } while (timeout > 1);

 flr_done:
-if (locked) {
-atomic_set(&adev->in_gpu_reset, 0);
-mutex_unlock(&adev->lock_reset);
-}
+atomic_set(&adev->in_gpu_reset, 0);
+up_read(&adev->reset_sem);

 /* Trigger recovery for world switch failure if no TDR */
 if (amdgpu_device_should_recover_gpu(adev)
--
2.17.1



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