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R. Silva" To: Vitor Soares , Boris Brezillon , =?utf-8?Q?Przemys=C5=82aw?= Gaj Subject: [PATCH] i3c: master: Replace zero-length array with flexible-array member Message-ID: <20200227131307.GA24935@embeddedor> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - gator4166.hostgator.com X-AntiAbuse: Original Domain - lists.infradead.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - embeddedor.com X-BWhitelist: no X-Source-IP: 201.162.161.188 X-Source-L: No X-Exim-ID: 1j7Ive-000s4k-OE X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [201.162.161.188]:40506 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 4 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200227_051019_764998_8AF807F8 X-CRM114-Status: UNSURE ( 6.75 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-i3c@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux I3C List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-i3c@lists.infradead.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-i3c" Errors-To: linux-i3c-bounces+linux-i3c=archiver.kernel.org@lists.infradead.org The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva --- drivers/i3c/master/dw-i3c-master.c | 2 +- drivers/i3c/master/i3c-master-cdns.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/i3c/master/dw-i3c-master.c b/drivers/i3c/master/dw-i3c-master.c index bd26c3b9634e..5c5306cd50ec 100644 --- a/drivers/i3c/master/dw-i3c-master.c +++ b/drivers/i3c/master/dw-i3c-master.c @@ -221,7 +221,7 @@ struct dw_i3c_xfer { struct completion comp; int ret; unsigned int ncmds; - struct dw_i3c_cmd cmds[0]; + struct dw_i3c_cmd cmds[]; }; struct dw_i3c_master { diff --git a/drivers/i3c/master/i3c-master-cdns.c b/drivers/i3c/master/i3c-master-cdns.c index 54712793709e..3fee8bd7fe20 100644 --- a/drivers/i3c/master/i3c-master-cdns.c +++ b/drivers/i3c/master/i3c-master-cdns.c @@ -388,7 +388,7 @@ struct cdns_i3c_xfer { struct completion comp; int ret; unsigned int ncmds; - struct cdns_i3c_cmd cmds[0]; + struct cdns_i3c_cmd cmds[]; }; struct cdns_i3c_data { -- 2.25.0 _______________________________________________ linux-i3c mailing list linux-i3c@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-i3c