Messages in this thread | | | Date | Sat, 18 Apr 2020 16:38:28 -0500 | From | "Gustavo A. R. Silva" <> | Subject | [GIT PULL] flexible-array member convertion patches for 5.7-rc2 |
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The following changes since commit 8f3d9f354286745c751374f5f1fcafee6b3f3136:
Linux 5.7-rc1 (2020-04-12 12:35:55 -0700)
are available in the Git repository at:
git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux.git tags/flexible-array-member-5.7-rc2
for you to fetch changes up to 43951585e1308b322c8ee31a4aafd08213f5c5d7:
xattr.h: Replace zero-length array with flexible-array member (2020-04-18 15:44:56 -0500)
---------------------------------------------------------------- flexible-array member convertion patches for 5.7-rc2
Hi Linus,
Please, pull the following patches that replace zero-length arrays with flexible-array members.
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 convertions) will also help to get completely rid of those sorts of issues.
Notice that all of these patches have been baking in linux-next for quite a while now and, 238 more of these patches have already been merged into 5.7-rc1.
There are a couple hundred more of these issues waiting to be addressed in the whole codebase.
[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")
Thanks
---------------------------------------------------------------- Gustavo A. R. Silva (28): bio: Replace zero-length array with flexible-array member blk-mq: Replace zero-length array with flexible-array member blk_types: Replace zero-length array with flexible-array member can: dev: peak_canfd.h: Replace zero-length array with flexible-array member digsig.h: Replace zero-length array with flexible-array member dirent.h: Replace zero-length array with flexible-array member enclosure.h: Replace zero-length array with flexible-array member energy_model.h: Replace zero-length array with flexible-array member ethtool.h: Replace zero-length array with flexible-array member genalloc.h: Replace zero-length array with flexible-array member igmp.h: Replace zero-length array with flexible-array member ihex.h: Replace zero-length array with flexible-array member irq.h: Replace zero-length array with flexible-array member lib: cpu_rmap: Replace zero-length array with flexible-array member list_lru.h: Replace zero-length array with flexible-array member memcontrol.h: Replace zero-length array with flexible-array member platform_data: wilco-ec.h: Replace zero-length array with flexible-array member posix_acl.h: Replace zero-length array with flexible-array member rio.h: Replace zero-length array with flexible-array member rslib.h: Replace zero-length array with flexible-array member sched: topology.h: Replace zero-length array with flexible-array member skbuff.h: Replace zero-length array with flexible-array member swap.h: Replace zero-length array with flexible-array member ti_wilink_st.h: Replace zero-length array with flexible-array member tpm_eventlog.h: Replace zero-length array with flexible-array member uapi: linux: dlm_device.h: Replace zero-length array with flexible-array member uapi: linux: fiemap.h: Replace zero-length array with flexible-array member xattr.h: Replace zero-length array with flexible-array member
include/linux/bio.h | 2 +- include/linux/blk-mq.h | 2 +- include/linux/blk_types.h | 2 +- include/linux/can/dev/peak_canfd.h | 4 ++-- include/linux/cpu_rmap.h | 2 +- include/linux/digsig.h | 4 ++-- include/linux/dirent.h | 2 +- include/linux/enclosure.h | 2 +- include/linux/energy_model.h | 2 +- include/linux/ethtool.h | 4 ++-- include/linux/genalloc.h | 2 +- include/linux/igmp.h | 2 +- include/linux/ihex.h | 2 +- include/linux/irq.h | 4 ++-- include/linux/list_lru.h | 2 +- include/linux/memcontrol.h | 4 ++-- include/linux/platform_data/wilco-ec.h | 2 +- include/linux/posix_acl.h | 2 +- include/linux/rio.h | 4 ++-- include/linux/rslib.h | 2 +- include/linux/sched/topology.h | 2 +- include/linux/skbuff.h | 2 +- include/linux/swap.h | 2 +- include/linux/ti_wilink_st.h | 6 +++--- include/linux/tpm_eventlog.h | 6 +++--- include/linux/xattr.h | 2 +- include/uapi/linux/dlm_device.h | 4 ++-- include/uapi/linux/fiemap.h | 2 +- 28 files changed, 39 insertions(+), 39 deletions(-)
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