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R. Silva" To: James Smart , Keith Busch , Jens Axboe , Christoph Hellwig , Sagi Grimberg Subject: [PATCH] nvme: Replace zero-length array with flexible-array member Message-ID: <20200226211602.GA18590@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: 200.39.29.129 X-Source-L: No X-Exim-ID: 1j73zS-000iA7-Nm X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [200.39.29.129]:47544 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 6 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200226_131329_561347_A1818BC0 X-CRM114-Status: UNSURE ( 9.48 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, "Gustavo A. R. Silva" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=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/nvme/host/fc.c | 2 +- drivers/nvme/host/lightnvm.c | 2 +- include/linux/nvme.h | 2 +- 3 files changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c index 5a70ac395d53..6806a19707fb 100644 --- a/drivers/nvme/host/fc.c +++ b/drivers/nvme/host/fc.c @@ -96,7 +96,7 @@ struct nvme_fc_fcp_op { struct nvme_fcp_op_w_sgl { struct nvme_fc_fcp_op op; struct scatterlist sgl[NVME_INLINE_SG_CNT]; - uint8_t priv[0]; + uint8_t priv[]; }; struct nvme_fc_lport { diff --git a/drivers/nvme/host/lightnvm.c b/drivers/nvme/host/lightnvm.c index ec46693f6b64..3002bf972c6b 100644 --- a/drivers/nvme/host/lightnvm.c +++ b/drivers/nvme/host/lightnvm.c @@ -171,7 +171,7 @@ struct nvme_nvm_bb_tbl { __le32 tdresv; __le32 thresv; __le32 rsvd2[8]; - __u8 blk[0]; + __u8 blk[]; }; struct nvme_nvm_id20_addrf { diff --git a/include/linux/nvme.h b/include/linux/nvme.h index 3d5189f46cb1..6ee80a44ed4f 100644 --- a/include/linux/nvme.h +++ b/include/linux/nvme.h @@ -1177,7 +1177,7 @@ struct nvmf_disc_rsp_page_hdr { __le64 numrec; __le16 recfmt; __u8 resv14[1006]; - struct nvmf_disc_rsp_page_entry entries[0]; + struct nvmf_disc_rsp_page_entry entries[]; }; enum { -- 2.25.0 _______________________________________________ linux-nvme mailing list linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme