linux-kernel - [PATCH] dma-debug: Track bucket lock state for static checkers

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Message-Id: <20160701191552.24295-1-sboyd@codeaurora.org>
Date:	Fri,  1 Jul 2016 12:15:52 -0700
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: [PATCH] dma-debug: Track bucket lock state for static checkers

get_hash_bucket() and put_hash_bucket() acquire and release the
same spinlock, but this confuses static checkers such as sparse

lib/dma-debug.c:254:27: warning: context imbalance in 'get_hash_bucket' - wrong count at exit
lib/dma-debug.c:268:13: warning: context imbalance in 'put_hash_bucket' - unexpected unlock

Add the appropriate acquire and release statements so that
checkers can properly track the lock state.

Signed-off-by: Stephen Boyd <sboyd@...eaurora.org>
---
 lib/dma-debug.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index 51a76af25c66..fcfa1939ac41 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -253,6 +253,7 @@ static int hash_fn(struct dma_debug_entry *entry)
  */
 static struct hash_bucket *get_hash_bucket(struct dma_debug_entry *entry,
 					   unsigned long *flags)
+	__acquires(&dma_entry_hash[idx].lock)
 {
 	int idx = hash_fn(entry);
 	unsigned long __flags;
@@ -267,6 +268,7 @@ static struct hash_bucket *get_hash_bucket(struct dma_debug_entry *entry,
  */
 static void put_hash_bucket(struct hash_bucket *bucket,
 			    unsigned long *flags)
+	__releases(&bucket->lock)
 {
 	unsigned long __flags = *flags;
 
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