diff options
| author | Gustavo A. R. Silva | 2020-03-19 18:09:37 -0500 |
|---|---|---|
| committer | Dan Williams | 2020-03-30 12:37:29 -0700 |
| commit | 9106137c6f0d0d959a855ad6885c6b3cb010ff98 (patch) | |
| tree | a8873aefe063d3a7ce005ca7e7522885ff8de4f1 | |
| parent | 1e361632da12ac00cb86c25a857ba251fdf2de95 (diff) | |
libnvdimm/region: 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://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 <gustavo@embeddedor.com>
Link: https://lore.kernel.org/r/20200319230937.GA16648@embeddedor.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
| -rw-r--r-- | drivers/nvdimm/nd.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/nvdimm/nd.h b/drivers/nvdimm/nd.h index c9f6a5b5253a..2cf77bc859c1 100644 --- a/drivers/nvdimm/nd.h +++ b/drivers/nvdimm/nd.h @@ -39,7 +39,7 @@ struct nd_region_data { int ns_count; int ns_active; unsigned int hints_shift; - void __iomem *flush_wpq[0]; + void __iomem *flush_wpq[]; }; static inline void __iomem *ndrd_get_flush_wpq(struct nd_region_data *ndrd, @@ -156,7 +156,7 @@ struct nd_region { struct nd_interleave_set *nd_set; struct nd_percpu_lane __percpu *lane; int (*flush)(struct nd_region *nd_region, struct bio *bio); - struct nd_mapping mapping[0]; + struct nd_mapping mapping[]; }; struct nd_blk_region { |