kernel_optimize_test/drivers/md/persistent-data
Gustavo A. R. Silva b18ae8dd9d dm: 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 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2020-05-20 17:09:44 -04:00
..
dm-array.c
dm-array.h
dm-bitset.c
dm-bitset.h
dm-block-manager.c dm persistent data: Simplify stack trace handling 2019-04-29 12:37:52 +02:00
dm-block-manager.h
dm-btree-internal.h dm: replace zero-length array with flexible-array 2020-05-20 17:09:44 -04:00
dm-btree-remove.c dm btree: increase rebalance threshold in __rebalance2() 2019-12-05 15:27:52 -05:00
dm-btree-spine.c dm persistent data: switch exit_ro_spine to return void 2020-05-15 10:29:35 -04:00
dm-btree.c dm btree: fix order of block initialization in btree_split_beneath 2019-08-22 16:11:23 -04:00
dm-btree.h
dm-persistent-data-internal.h
dm-space-map-common.c dm space map common: fix to ensure new block isn't already in use 2020-01-14 20:15:53 -05:00
dm-space-map-common.h dm space map common: fix to ensure new block isn't already in use 2020-01-14 20:15:53 -05:00
dm-space-map-disk.c dm space map common: fix to ensure new block isn't already in use 2020-01-14 20:15:53 -05:00
dm-space-map-disk.h
dm-space-map-metadata.c dm space map common: fix to ensure new block isn't already in use 2020-01-14 20:15:53 -05:00
dm-space-map-metadata.h
dm-space-map.h
dm-transaction-manager.c
dm-transaction-manager.h
Kconfig treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
Makefile