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author | Gustavo A. R. Silva <gustavoars@kernel.org> | 2020-05-07 13:53:42 -0500 |
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committer | Jason Gunthorpe <jgg@mellanox.com> | 2020-05-13 12:01:56 -0300 |
commit | 0cb9e4f9e98af4b969b9140e964c646ad6ed7d40 (patch) | |
tree | 55748f433869763cbdcb88b1f3092c1864dbcd19 /include/rdma | |
parent | a0e46db4e764f56c61f85c235c50bf4578c51a47 (diff) | |
download | linux-0cb9e4f9e98af4b969b9140e964c646ad6ed7d40.tar.bz2 |
IB/rdmavt: 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")
Link: https://lore.kernel.org/r/20200507185342.GA14476@embeddedor
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Diffstat (limited to 'include/rdma')
-rw-r--r-- | include/rdma/rdmavt_qp.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/rdma/rdmavt_qp.h b/include/rdma/rdmavt_qp.h index 5fc10108703a..982bf2340840 100644 --- a/include/rdma/rdmavt_qp.h +++ b/include/rdma/rdmavt_qp.h @@ -440,7 +440,7 @@ struct rvt_qp { /* * This sge list MUST be last. Do not add anything below here. */ - struct rvt_sge r_sg_list[0] /* verified SGEs */ + struct rvt_sge r_sg_list[] /* verified SGEs */ ____cacheline_aligned_in_smp; }; |