Commit 7ffb5ced authored by Koby Elbaz's avatar Koby Elbaz Committed by Oded Gabbay
Browse files

accel/habanalabs: use a mutex rather than a spinlock 



There are two reasons why mutex is better here:
1. There's a critical section relatively long, where in
certain scenarios (e.g., multiple VM allocations) taking a spinlock
might cause noticeable performance degradation.
2. It will remove the incorrect usage of mutex under
spin_lock (where preemption is disabled).

Reported-by: default avatarDan Carpenter <error27@gmail.com>
Signed-off-by: default avatarKoby Elbaz <kelbaz@habana.ai>
Reviewed-by: default avatarOded Gabbay <ogabbay@kernel.org>
Signed-off-by: default avatarOded Gabbay <ogabbay@kernel.org>
parent c7ac65c8

drivers/accel/habanalabs/common/debugfs.c

+8 −7
Original line number Diff line number Diff line
@@ -258,7 +258,7 @@ static int vm_show(struct seq_file *s, void *data) 
	if (!dev_entry->hdev->mmu_enable)

		return 0;



	spin_lock(&dev_entry->ctx_mem_hash_spinlock);

	mutex_lock(&dev_entry->ctx_mem_hash_mutex);



	list_for_each_entry(ctx, &dev_entry->ctx_mem_hash_list, debugfs_list) {

		once = false;
@@ -329,7 +329,7 @@ static int vm_show(struct seq_file *s, void *data) 


	}



	spin_unlock(&dev_entry->ctx_mem_hash_spinlock);

	mutex_unlock(&dev_entry->ctx_mem_hash_mutex);



	ctx = hl_get_compute_ctx(dev_entry->hdev);

	if (ctx) {
@@ -1785,7 +1785,7 @@ void hl_debugfs_add_device(struct hl_device *hdev) 
	spin_lock_init(&dev_entry->cs_spinlock);

	spin_lock_init(&dev_entry->cs_job_spinlock);

	spin_lock_init(&dev_entry->userptr_spinlock);

	spin_lock_init(&dev_entry->ctx_mem_hash_spinlock);

	mutex_init(&dev_entry->ctx_mem_hash_mutex);



	dev_entry->root = debugfs_create_dir(dev_name(hdev->dev),

						hl_debug_root);
@@ -1802,6 +1802,7 @@ void hl_debugfs_remove_device(struct hl_device *hdev) 


	debugfs_remove_recursive(entry->root);



	mutex_destroy(&entry->ctx_mem_hash_mutex);

	mutex_destroy(&entry->file_mutex);



	vfree(entry->data_dma_blob_desc.data);
@@ -1908,18 +1909,18 @@ void hl_debugfs_add_ctx_mem_hash(struct hl_device *hdev, struct hl_ctx *ctx) 
{

	struct hl_dbg_device_entry *dev_entry = &hdev->hl_debugfs;



	spin_lock(&dev_entry->ctx_mem_hash_spinlock);

	mutex_lock(&dev_entry->ctx_mem_hash_mutex);

	list_add(&ctx->debugfs_list, &dev_entry->ctx_mem_hash_list);

	spin_unlock(&dev_entry->ctx_mem_hash_spinlock);

	mutex_unlock(&dev_entry->ctx_mem_hash_mutex);

}



void hl_debugfs_remove_ctx_mem_hash(struct hl_device *hdev, struct hl_ctx *ctx)

{

	struct hl_dbg_device_entry *dev_entry = &hdev->hl_debugfs;



	spin_lock(&dev_entry->ctx_mem_hash_spinlock);

	mutex_lock(&dev_entry->ctx_mem_hash_mutex);

	list_del(&ctx->debugfs_list);

	spin_unlock(&dev_entry->ctx_mem_hash_spinlock);

	mutex_unlock(&dev_entry->ctx_mem_hash_mutex);

}



/**

drivers/accel/habanalabs/common/habanalabs.h

+2 −2
Original line number Diff line number Diff line
@@ -2320,7 +2320,7 @@ struct hl_debugfs_entry { 
 * @userptr_list: list of available userptrs (virtual memory chunk descriptor).

 * @userptr_spinlock: protects userptr_list.

 * @ctx_mem_hash_list: list of available contexts with MMU mappings.

 * @ctx_mem_hash_spinlock: protects cb_list.

 * @ctx_mem_hash_mutex: protects list of available contexts with MMU mappings.

 * @data_dma_blob_desc: data DMA descriptor of blob.

 * @mon_dump_blob_desc: monitor dump descriptor of blob.

 * @state_dump: data of the system states in case of a bad cs.
@@ -2351,7 +2351,7 @@ struct hl_dbg_device_entry { 
	struct list_head		userptr_list;

	spinlock_t			userptr_spinlock;

	struct list_head		ctx_mem_hash_list;

	spinlock_t			ctx_mem_hash_spinlock;

	struct mutex			ctx_mem_hash_mutex;

	struct debugfs_blob_wrapper	data_dma_blob_desc;

	struct debugfs_blob_wrapper	mon_dump_blob_desc;

	char				*state_dump[HL_STATE_DUMP_HIST_LEN];