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authorGustavo A. R. Silva <gustavo@embeddedor.com>2020-03-19 18:09:37 -0500
committerDan Williams <dan.j.williams@intel.com>2020-03-30 12:37:29 -0700
commit9106137c6f0d0d959a855ad6885c6b3cb010ff98 (patch)
treea8873aefe063d3a7ce005ca7e7522885ff8de4f1 /drivers/nvdimm
parent1e361632da12ac00cb86c25a857ba251fdf2de95 (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>
Diffstat (limited to 'drivers/nvdimm')
-rw-r--r--drivers/nvdimm/nd.h4
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 {