From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: + ocfs2-dlm-replace-zero-length-array-with-flexible-array-member.patch added to -mm tree Date: Mon, 09 Mar 2020 19:54:00 -0700 Message-ID: <20200310025400.URhk7jn_S%akpm@linux-foundation.org> References: <20200305222751.6d781a3f2802d79510941e4e@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:45928 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726156AbgCJCyC (ORCPT ); Mon, 9 Mar 2020 22:54:02 -0400 In-Reply-To: <20200305222751.6d781a3f2802d79510941e4e@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: gechangwei@live.cn, ghe@suse.com, gustavo@embeddedor.com, jlbec@evilplan.org, joseph.qi@linux.alibaba.com, junxiao.bi@oracle.com, mark@fasheh.com, mm-commits@vger.kernel.org, piaojun@huawei.com The patch titled Subject: ocfs2: dlm: replace zero-length array with flexible-array member has been added to the -mm tree. Its filename is ocfs2-dlm-replace-zero-length-array-with-flexible-array-member.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/ocfs2-dlm-replace-zero-length-array-with-flexible-array-member.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/ocfs2-dlm-replace-zero-length-array-with-flexible-array-member.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: "Gustavo A. R. Silva" Subject: ocfs2: dlm: replace zero-length array with flexible-array member 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://urldefense.com/v3/__https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html__;!!GqivPVa7Brio!OVOYL_CouISa5L1Lw-20EEFQntw6cKMx-j8UdY4z78uYgzKBUFcfpn50GaurvbV5v7YiUA$ [2] https://urldefense.com/v3/__https://github.com/KSPP/linux/issues/21__;!!GqivPVa7Brio!OVOYL_CouISa5L1Lw-20EEFQntw6cKMx-j8UdY4z78uYgzKBUFcfpn50GaurvbXs8Eh8eg$ [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Link: http://lkml.kernel.org/r/20200309202016.GA8210@embeddedor Signed-off-by: Gustavo A. R. Silva Acked-by: Joseph Qi Cc: Mark Fasheh Cc: Joel Becker Cc: Junxiao Bi Cc: Changwei Ge Cc: Gang He Cc: Jun Piao Signed-off-by: Andrew Morton --- fs/ocfs2/dlm/dlmcommon.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) --- a/fs/ocfs2/dlm/dlmcommon.h~ocfs2-dlm-replace-zero-length-array-with-flexible-array-member +++ a/fs/ocfs2/dlm/dlmcommon.h @@ -564,7 +564,7 @@ struct dlm_migratable_lockres // 48 bytes u8 lvb[DLM_LVB_LEN]; // 112 bytes - struct dlm_migratable_lock ml[0]; // 16 bytes each, begins at byte 112 + struct dlm_migratable_lock ml[]; // 16 bytes each, begins at byte 112 }; #define DLM_MIG_LOCKRES_MAX_LEN \ (sizeof(struct dlm_migratable_lockres) + \ @@ -601,7 +601,7 @@ struct dlm_convert_lock u8 name[O2NM_MAX_NAME_LEN]; - s8 lvb[0]; + s8 lvb[]; }; #define DLM_CONVERT_LOCK_MAX_LEN (sizeof(struct dlm_convert_lock)+DLM_LVB_LEN) @@ -616,7 +616,7 @@ struct dlm_unlock_lock u8 name[O2NM_MAX_NAME_LEN]; - s8 lvb[0]; + s8 lvb[]; }; #define DLM_UNLOCK_LOCK_MAX_LEN (sizeof(struct dlm_unlock_lock)+DLM_LVB_LEN) @@ -632,7 +632,7 @@ struct dlm_proxy_ast u8 name[O2NM_MAX_NAME_LEN]; - s8 lvb[0]; + s8 lvb[]; }; #define DLM_PROXY_AST_MAX_LEN (sizeof(struct dlm_proxy_ast)+DLM_LVB_LEN) _ Patches currently in -mm which might be from gustavo@embeddedor.com are ocfs2-replace-zero-length-array-with-flexible-array-member.patch ocfs2-cluster-replace-zero-length-array-with-flexible-array-member.patch ocfs2-dlm-replace-zero-length-array-with-flexible-array-member.patch ocfs2-ocfs2_fsh-replace-zero-length-array-with-flexible-array-member.patch lib-bch-replace-zero-length-array-with-flexible-array-member.patch lib-ts_bm-replace-zero-length-array-with-flexible-array-member.patch lib-ts_fsm-replace-zero-length-array-with-flexible-array-member.patch lib-ts_kmp-replace-zero-length-array-with-flexible-array-member.patch gcov-gcc_4_7-replace-zero-length-array-with-flexible-array-member.patch gcov-gcc_3_4-replace-zero-length-array-with-flexible-array-member.patch gcov-fs-replace-zero-length-array-with-flexible-array-member.patch