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author | Gustavo A. R. Silva <gustavoars@kernel.org> | 2020-05-07 22:04:52 +0300 |
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committer | Christoph Hellwig <hch@lst.de> | 2020-05-27 08:12:37 +0300 |
commit | f1e71d75f04792721d411170168e68019ccb7de3 (patch) | |
tree | 451364bcc1754532354e0cd286b1b3bfa15eb481 /include/linux/nvme.h | |
parent | 68ab60ca2d6bd8e6b1ecc2857a174c1c2b9451e9 (diff) | |
download | linux-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.h | 2 |
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 { |