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[96.50.97.138]) by mx.google.com with ESMTPSA id c2sm6945161pds.32.2014.09.02.15.33.14 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 02 Sep 2014 15:33:15 -0700 (PDT) From: behanw@converseincode.com To: agk@redhat.com, clm@fb.com, davem@davemloft.net, dm-devel@redhat.com, fabf@skynet.be, herbert@gondor.apana.org.au, jbacik@fb.com, snitzer@redhat.com Cc: akpm@linux-foundation.org, james.l.morris@oracle.com, john.johansen@canonical.com, linux-btrfs@vger.kernel.org, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, linux-security-module@vger.kernel.org, neilb@suse.de, serge@hallyn.com, torvalds@linux-foundation.org, =?UTF-8?q?Jan-Simon=20M=C3=B6ller?= , Behan Webster , pageexec@freemail.hu Subject: [PATCH RFC 3/6] crypto: LLVMLinux: Remove VLAIS usage from libcrc32c.c Date: Tue, 2 Sep 2014 15:32:30 -0700 Message-Id: <1409697153-7006-4-git-send-email-behanw@converseincode.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1409697153-7006-1-git-send-email-behanw@converseincode.com> References: <1409697153-7006-1-git-send-email-behanw@converseincode.com> MIME-Version: 1.0 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Spam-Status: No, score=-8.5 required=5.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,RP_MATCHES_RCVD,T_DKIM_INVALID,UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Jan-Simon Möller The use of variable length arrays in structs (VLAIS) in the Linux Kernel code precludes the use of compilers which don't implement VLAIS (for instance the Clang compiler). This patch instead allocates the appropriate amount of memory using an char array. struct shash_desc contains a flexible array member member ctx declared with CRYPTO_MINALIGN_ATTR, so sizeof(struct shash_desc) aligns the beginning of the array declared after struct shash_desc with long long. No trailing padding is required because it is not a struct type that can be used in an array. The CRYPTO_MINALIGN_ATTR is required so that desc is aligned with long long as would be the case for a struct containing a member with CRYPTO_MINALIGN_ATTR. Signed-off-by: Jan-Simon Möller Signed-off-by: Behan Webster Cc: pageexec@freemail.hu --- lib/libcrc32c.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/lib/libcrc32c.c b/lib/libcrc32c.c index b3131f5..03f2cf3 100644 --- a/lib/libcrc32c.c +++ b/lib/libcrc32c.c @@ -41,20 +41,20 @@ static struct crypto_shash *tfm; u32 crc32c(u32 crc, const void *address, unsigned int length) { - struct { - struct shash_desc shash; - char ctx[crypto_shash_descsize(tfm)]; - } desc; + char desc[sizeof(struct shash_desc) + + crypto_shash_descsize(tfm)] CRYPTO_MINALIGN_ATTR; + struct shash_desc *shash = (struct shash_desc *)desc; + 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; } EXPORT_SYMBOL(crc32c);