Re: [Freedreno] [PATCH v2 2/4] drm/msm: make msm_disp_state transient data struct

abhinavk@xxxxxxxxxxxxxx · Tue, 27 Apr 2021 12:19:52 -0700

Hi Dmitry

On 2021-04-26 17:18, Dmitry Baryshkov wrote:
Instead of allocating snapshotting structure at the driver probe time
and later handling concurrent access, actual state, etc, make
msm_disp_state transient struct. Allocate one when snapshotting happens
and free it after coredump data is read by userspace.

Can you please check my previous comment on coredump_pending?

https://lore.kernel.org/dri-devel/186825e2fb7bea8d45f33b5c1fa3509f@xxxxxxxxxxxxxx/T/#u

That helps to serialize read/write of coredump.

Rest of the changes on this one look fine to me.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
---
 drivers/gpu/drm/msm/disp/msm_disp_snapshot.c  | 90 ++++++-------------
 drivers/gpu/drm/msm/disp/msm_disp_snapshot.h  | 13 +--
 .../gpu/drm/msm/disp/msm_disp_snapshot_util.c |  5 +-
 drivers/gpu/drm/msm/msm_kms.h                 |  6 +-
 4 files changed, 37 insertions(+), 77 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/msm_disp_snapshot.c
b/drivers/gpu/drm/msm/disp/msm_disp_snapshot.c
index 70fd5a1fe13e..a4a7cb06bc87 100644
--- a/drivers/gpu/drm/msm/disp/msm_disp_snapshot.c
+++ b/drivers/gpu/drm/msm/disp/msm_disp_snapshot.c
@@ -7,8 +7,7 @@

 #include "msm_disp_snapshot.h"

-#ifdef CONFIG_DEV_COREDUMP
-static ssize_t disp_devcoredump_read(char *buffer, loff_t offset,
+static ssize_t __maybe_unused disp_devcoredump_read(char *buffer,
loff_t offset,
 		size_t count, void *data, size_t datalen)
 {
 	struct drm_print_iterator iter;
@@ -29,52 +28,47 @@ static ssize_t disp_devcoredump_read(char *buffer,
loff_t offset,
 	return count - iter.remain;
 }

-static void disp_devcoredump_free(void *data)
+static void _msm_disp_snapshot_work(struct kthread_work *work)
 {
+	struct msm_kms *kms = container_of(work, struct msm_kms, dump_work);
+	struct drm_device *drm_dev = kms->dev;
 	struct msm_disp_state *disp_state;
+	struct drm_printer p;

-	disp_state = data;
-
-	msm_disp_state_free(disp_state);
+	disp_state = kzalloc(sizeof(struct msm_disp_state), GFP_KERNEL);
+	if (!disp_state)
+		return;

-	disp_state->coredump_pending = false;
-}
-#endif /* CONFIG_DEV_COREDUMP */
+	disp_state->dev = drm_dev->dev;
+	disp_state->drm_dev = drm_dev;

-static void _msm_disp_snapshot_work(struct kthread_work *work)
-{
-	struct msm_disp_state *disp_state = container_of(work, struct
msm_disp_state, dump_work);
-	struct drm_printer p;
+	INIT_LIST_HEAD(&disp_state->blocks);

-	mutex_lock(&disp_state->mutex);
+	/* Serialize dumping here */
+	mutex_lock(&kms->dump_mutex);

 	msm_disp_snapshot_capture_state(disp_state);

+	mutex_unlock(&kms->dump_mutex);
+
 	if (MSM_DISP_SNAPSHOT_DUMP_IN_CONSOLE) {
 		p = drm_info_printer(disp_state->drm_dev->dev);
 		msm_disp_state_print(disp_state, &p);
 	}

 	/*
-	 * if devcoredump is not defined free the state immediately
-	 * otherwise it will be freed in the free handler.
+	 * If COREDUMP is disabled, the stub will call the free function.
+	 * If there is a codedump pending for the device, the dev_coredumpm()
+	 * will also free new coredump state.
 	 */
-#ifdef CONFIG_DEV_COREDUMP
 	dev_coredumpm(disp_state->dev, THIS_MODULE, disp_state, 0, 
GFP_KERNEL,
-			disp_devcoredump_read, disp_devcoredump_free);
-	disp_state->coredump_pending = true;
-#else
-	msm_disp_state_free(disp_state);
-#endif
-
-	mutex_unlock(&disp_state->mutex);
+			disp_devcoredump_read, msm_disp_state_free);
 }

 void msm_disp_snapshot_state(struct drm_device *drm_dev)
 {
 	struct msm_drm_private *priv;
 	struct msm_kms *kms;
-	struct msm_disp_state *disp_state;

 	if (!drm_dev) {
 		DRM_ERROR("invalid params\n");
@@ -83,30 +77,13 @@ void msm_disp_snapshot_state(struct drm_device 
*drm_dev)

 	priv = drm_dev->dev_private;
 	kms = priv->kms;
-	disp_state = kms->disp_state;
-
-	if (!disp_state) {
-		DRM_ERROR("invalid params\n");
-		return;
-	}

-	/*
-	 * if there is a coredump pending return immediately till dump
-	 * if read by userspace or timeout happens
-	 */
-	if (disp_state->coredump_pending) {
-		DRM_DEBUG("coredump is pending read\n");
-		return;
-	}
-
-	kthread_queue_work(disp_state->dump_worker,
-			&disp_state->dump_work);
+	kthread_queue_work(kms->dump_worker, &kms->dump_work);
 }

 int msm_disp_snapshot_init(struct drm_device *drm_dev)
 {
 	struct msm_drm_private *priv;
-	struct msm_disp_state *disp_state;
 	struct msm_kms *kms;

 	if (!drm_dev) {
@@ -117,22 +94,13 @@ int msm_disp_snapshot_init(struct drm_device 
*drm_dev)
 	priv = drm_dev->dev_private;
 	kms = priv->kms;

-	disp_state = devm_kzalloc(drm_dev->dev, sizeof(struct
msm_disp_state), GFP_KERNEL);
-
-	mutex_init(&disp_state->mutex);
+	mutex_init(&kms->dump_mutex);

-	disp_state->dev = drm_dev->dev;
-	disp_state->drm_dev = drm_dev;
-
-	INIT_LIST_HEAD(&disp_state->blocks);
-
-	disp_state->dump_worker = kthread_create_worker(0, "%s", 
"disp_snapshot");
-	if (IS_ERR(disp_state->dump_worker))
+	kms->dump_worker = kthread_create_worker(0, "%s", "disp_snapshot");
+	if (IS_ERR(kms->dump_worker))
 		DRM_ERROR("failed to create disp state task\n");

-	kthread_init_work(&disp_state->dump_work, _msm_disp_snapshot_work);
-
-	kms->disp_state = disp_state;
+	kthread_init_work(&kms->dump_work, _msm_disp_snapshot_work);

 	return 0;
 }
@@ -141,7 +109,6 @@ void msm_disp_snapshot_destroy(struct drm_device 
*drm_dev)
 {
 	struct msm_kms *kms;
 	struct msm_drm_private *priv;
-	struct msm_disp_state *disp_state;

 	if (!drm_dev) {
 		DRM_ERROR("invalid params\n");
@@ -150,12 +117,9 @@ void msm_disp_snapshot_destroy(struct drm_device 
*drm_dev)

 	priv = drm_dev->dev_private;
 	kms = priv->kms;
-	disp_state = kms->disp_state;
-
-	if (disp_state->dump_worker)
-		kthread_destroy_worker(disp_state->dump_worker);

-	list_del(&disp_state->blocks);
+	if (kms->dump_worker)
+		kthread_destroy_worker(kms->dump_worker);

-	mutex_destroy(&disp_state->mutex);
+	mutex_destroy(&kms->dump_mutex);
 }
diff --git a/drivers/gpu/drm/msm/disp/msm_disp_snapshot.h
b/drivers/gpu/drm/msm/disp/msm_disp_snapshot.h
index 32f52799a1ba..c6174a366095 100644
--- a/drivers/gpu/drm/msm/disp/msm_disp_snapshot.h
+++ b/drivers/gpu/drm/msm/disp/msm_disp_snapshot.h
@@ -41,26 +41,17 @@
  * struct msm_disp_state - structure to store current dpu state
  * @dev: device pointer
  * @drm_dev: drm device pointer
- * @mutex: mutex to serialize access to serialze dumps, debugfs access
- * @coredump_pending: coredump is pending read from userspace
  * @atomic_state: atomic state duplicated at the time of the error
- * @dump_worker: kworker thread which runs the dump work
- * @dump_work: kwork which dumps the registers and drm state
  * @timestamp: timestamp at which the coredump was captured
  */
 struct msm_disp_state {
 	struct device *dev;
 	struct drm_device *drm_dev;
-	struct mutex mutex;
-
-	bool coredump_pending;

 	struct list_head blocks;

 	struct drm_atomic_state *atomic_state;

-	struct kthread_worker *dump_worker;
-	struct kthread_work dump_work;
 	ktime_t timestamp;
 };

@@ -123,11 +114,11 @@ void msm_disp_snapshot_capture_state(struct
msm_disp_state *disp_state);

 /**
  * msm_disp_state_free - free the memory after the coredump has been 
read
- * @disp_state:	    handle to struct msm_disp_state
+ * @data:	    handle to struct msm_disp_state

  * Returns: none
  */
-void msm_disp_state_free(struct msm_disp_state *disp_state);
+void msm_disp_state_free(void *data);

 /**
  * msm_disp_snapshot_add_block - add a hardware block with its 
register dump
diff --git a/drivers/gpu/drm/msm/disp/msm_disp_snapshot_util.c
b/drivers/gpu/drm/msm/disp/msm_disp_snapshot_util.c
index ca6632550337..cabe15190ec1 100644
--- a/drivers/gpu/drm/msm/disp/msm_disp_snapshot_util.c
+++ b/drivers/gpu/drm/msm/disp/msm_disp_snapshot_util.c
@@ -142,8 +142,9 @@ void msm_disp_snapshot_capture_state(struct
msm_disp_state *disp_state)
 	msm_disp_capture_atomic_state(disp_state);
 }

-void msm_disp_state_free(struct msm_disp_state *disp_state)
+void msm_disp_state_free(void *data)
 {
+	struct msm_disp_state *disp_state = data;
 	struct msm_disp_state_block *block, *tmp;

 	if (disp_state->atomic_state) {
@@ -156,6 +157,8 @@ void msm_disp_state_free(struct msm_disp_state 
*disp_state)
 		kfree(block->state);
 		kfree(block);
 	}
+
+	kfree(disp_state);
 }

 void msm_disp_snapshot_add_block(struct msm_disp_state *disp_state, 
u32 len,
diff --git a/drivers/gpu/drm/msm/msm_kms.h 
b/drivers/gpu/drm/msm/msm_kms.h
index 146dcab123f4..086a2d59b8c8 100644
--- a/drivers/gpu/drm/msm/msm_kms.h
+++ b/drivers/gpu/drm/msm/msm_kms.h
@@ -156,8 +156,10 @@ struct msm_kms {
 	/* mapper-id used to request GEM buffer mapped for scanout: */
 	struct msm_gem_address_space *aspace;

-	/* handle to disp snapshot state */
-	struct msm_disp_state *disp_state;
+	/* disp snapshot support */
+	struct kthread_worker *dump_worker;
+	struct kthread_work dump_work;
+	struct mutex dump_mutex;

 	/*
 	 * For async commit, where ->flush_commit() and later happens
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