From: Dima Zavin <dima@android.com>
Date: Tue, 26 Oct 2010 21:21:54 +0000 (-0700)
Subject: mm: add a might_sleep_if() to dma_pool_alloc()
X-Git-Tag: firefly_0821_release~7613^2~3628^2~128
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=ea05c8444e451f1cfbf78c68733e717ad7b8602b;p=firefly-linux-kernel-4.4.55.git

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>
---

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) {