Patch "dma-buf: cma_heap: Fix mutex locking section" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    dma-buf: cma_heap: Fix mutex locking section

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     dma-buf-cma_heap-fix-mutex-locking-section.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 2b557880b5c68916a65eb9f2c908842782dd6c0f
Author: Weizhao Ouyang <o451686892@xxxxxxxxx>
Date:   Tue Jan 4 15:35:45 2022 +0800

    dma-buf: cma_heap: Fix mutex locking section
    
    [ Upstream commit 54329e6f7beea6af56c1230da293acc97d6a6ee7 ]
    
    Fix cma_heap_buffer mutex locking critical section to protect vmap_cnt
    and vaddr.
    
    Fixes: a5d2d29e24be ("dma-buf: heaps: Move heap-helper logic into the cma_heap implementation")
    Signed-off-by: Weizhao Ouyang <o451686892@xxxxxxxxx>
    Acked-by: John Stultz <john.stultz@xxxxxxxxxx>
    Signed-off-by: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
    Link: https://patchwork.freedesktop.org/patch/msgid/20220104073545.124244-1-o451686892@xxxxxxxxx
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma-buf/heaps/cma_heap.c
index 0c05b79870f96..83f02bd51dda6 100644
--- a/drivers/dma-buf/heaps/cma_heap.c
+++ b/drivers/dma-buf/heaps/cma_heap.c
@@ -124,10 +124,11 @@ static int cma_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
 	struct cma_heap_buffer *buffer = dmabuf->priv;
 	struct dma_heap_attachment *a;
 
+	mutex_lock(&buffer->lock);
+
 	if (buffer->vmap_cnt)
 		invalidate_kernel_vmap_range(buffer->vaddr, buffer->len);
 
-	mutex_lock(&buffer->lock);
 	list_for_each_entry(a, &buffer->attachments, list) {
 		if (!a->mapped)
 			continue;
@@ -144,10 +145,11 @@ static int cma_heap_dma_buf_end_cpu_access(struct dma_buf *dmabuf,
 	struct cma_heap_buffer *buffer = dmabuf->priv;
 	struct dma_heap_attachment *a;
 
+	mutex_lock(&buffer->lock);
+
 	if (buffer->vmap_cnt)
 		flush_kernel_vmap_range(buffer->vaddr, buffer->len);
 
-	mutex_lock(&buffer->lock);
 	list_for_each_entry(a, &buffer->attachments, list) {
 		if (!a->mapped)
 			continue;