mm: add a might_sleep_if() to dma_pool_alloc()

Buggy drivers (e.g.  fsl_udc) could call dma_pool_alloc from atomic
context with GFP_KERNEL.  In most instances, the first pool_alloc_page
call would succeed and the sleeping functions would never be called.  This
allowed the buggy drivers to slip through the cracks.

Add a might_sleep_if() checking for __GFP_WAIT in flags.

Signed-off-by: Dima Zavin <dima@android.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/mm/dmapool.c b/mm/dmapool.c
index 3df063706f53..4df2de77e069 100644
--- a/mm/dmapool.c
+++ b/mm/dmapool.c
@@ -311,6 +311,8 @@ void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
         size_t offset;
         void *retval;
 
+        might_sleep_if(mem_flags & __GFP_WAIT);
+
         spin_lock_irqsave(&pool->lock, flags);
  restart:
         list_for_each_entry(page, &pool->page_list, page_list) {