From: Vinícius Tinti <viniciusti...@gmail.com>

Replaced the use of a Variable Length Array In Struct (VLAIS) with a C99
compliant equivalent. This is the original VLAIS struct.

struct {
        struct shash_desc shash;
        char ctx[crypto_shash_descsize(tfm)];
} desc;

This patch instead allocates the appropriate amount of memory using a
char array using the SHASH_DESC_ON_STACK macro.

The new code can be compiled with both gcc and clang.

Signed-off-by: Vinícius Tinti <viniciusti...@gmail.com>
Reviewed-by: Jan-Simon Möller <dl...@gmx.de>
Reviewed-by: Mark Charlebois <charl...@gmail.com>
Signed-off-by: Behan Webster <beh...@converseincode.com>
Cc: "David S. Miller" <da...@davemloft.net>
Cc: Herbert Xu <herb...@gondor.apana.org.au>
---
 fs/btrfs/hash.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/fs/btrfs/hash.c b/fs/btrfs/hash.c
index 85889aa..4bf4d3a 100644
--- a/fs/btrfs/hash.c
+++ b/fs/btrfs/hash.c
@@ -33,18 +33,16 @@ void btrfs_hash_exit(void)
 
 u32 btrfs_crc32c(u32 crc, const void *address, unsigned int length)
 {
-       struct {
-               struct shash_desc shash;
-               char ctx[crypto_shash_descsize(tfm)];
-       } desc;
+       SHASH_DESC_ON_STACK(shash, tfm);
+       u32 *ctx = (u32 *)shash_desc_ctx(shash);
        int err;
 
-       desc.shash.tfm = tfm;
-       desc.shash.flags = 0;
-       *(u32 *)desc.ctx = crc;
+       shash->tfm = tfm;
+       shash->flags = 0;
+       *ctx = crc;
 
-       err = crypto_shash_update(&desc.shash, address, length);
+       err = crypto_shash_update(shash, address, length);
        BUG_ON(err);
 
-       return *(u32 *)desc.ctx;
+       return *ctx;
 }
-- 
1.9.1

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