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authorGustavo A. R. Silva <gustavoars@kernel.org>2020-05-07 22:04:52 +0300
committerChristoph Hellwig <hch@lst.de>2020-05-27 08:12:37 +0300
commitf1e71d75f04792721d411170168e68019ccb7de3 (patch)
tree451364bcc1754532354e0cd286b1b3bfa15eb481 /include/linux/nvme.h
parent68ab60ca2d6bd8e6b1ecc2857a174c1c2b9451e9 (diff)
downloadlinux-f1e71d75f04792721d411170168e68019ccb7de3.tar.xz
nvme: replace zero-length array with flexible-array
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] sizeof(flexible-array-member) triggers a warning because flexible array members have incomplete type[1]. There are some instances of code in which the sizeof operator is being incorrectly/erroneously applied to zero-length arrays and the result is zero. Such instances may be hiding some bugs. So, this work (flexible-array member conversions) will also help to get completely rid of those sorts of issues. 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 <gustavoars@kernel.org> Signed-off-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'include/linux/nvme.h')
-rw-r--r--include/linux/nvme.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/nvme.h b/include/linux/nvme.h
index b235a48eac8c..e2993e6a9d7c 100644
--- a/include/linux/nvme.h
+++ b/include/linux/nvme.h
@@ -1185,7 +1185,7 @@ 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 {