kernel_optimize_test/tools/perf/bench
Gustavo A. R. Silva 6549a8c0c3 perf tools: 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>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Gustavo A. R. Silva <gustavo@embeddedor.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20200515172926.GA31976@embeddedor
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2020-05-28 10:03:27 -03:00
..
bench.h perf bench: Add kallsyms parsing 2020-05-05 16:35:32 -03:00
Build perf bench: Add kallsyms parsing 2020-05-05 16:35:32 -03:00
epoll-ctl.c tools feature: Rename HAVE_EVENTFD to HAVE_EVENTFD_SUPPORT 2020-05-28 10:03:26 -03:00
epoll-wait.c tools feature: Rename HAVE_EVENTFD to HAVE_EVENTFD_SUPPORT 2020-05-28 10:03:26 -03:00
futex-hash.c perf bench: Fix div-by-zero if runtime is zero 2020-04-22 10:01:33 -03:00
futex-lock-pi.c perf bench: Fix div-by-zero if runtime is zero 2020-04-22 10:01:33 -03:00
futex-requeue.c perf bench: Clear struct sigaction before sigaction() syscall 2020-03-06 08:30:47 -03:00
futex-wake-parallel.c perf bench: Clear struct sigaction before sigaction() syscall 2020-03-06 08:30:47 -03:00
futex-wake.c perf bench: Clear struct sigaction before sigaction() syscall 2020-03-06 08:30:47 -03:00
futex.h perf bench: Move HAVE_PTHREAD_ATTR_SETAFFINITY_NP into bench.h 2018-11-21 12:00:32 -03:00
kallsyms-parse.c perf bench: Add kallsyms parsing 2020-05-05 16:35:32 -03:00
mem-functions.c perf tools: Move everything related to sys_perf_event_open() to perf-sys.h 2019-08-29 17:38:32 -03:00
mem-memcpy-arch.h
mem-memcpy-x86-64-asm-def.h
mem-memcpy-x86-64-asm.S tools arch: Update arch/x86/lib/memcpy_64.S copy used in 'perf bench mem memcpy' 2018-07-30 12:36:51 -03:00
mem-memcpy-x86-64-lib.c tools arch: Update arch/x86/lib/memcpy_64.S copy used in 'perf bench mem memcpy' 2018-07-30 12:36:51 -03:00
mem-memset-arch.h
mem-memset-x86-64-asm-def.h
mem-memset-x86-64-asm.S
numa.c perf tools: Remove needless builtin.h include directives 2019-09-20 09:19:20 -03:00
sched-messaging.c perf tools: Replace zero-length array with flexible-array 2020-05-28 10:03:27 -03:00
sched-pipe.c perf tools: Remove util.h from where it is not needed 2019-09-20 09:19:20 -03:00
synthesize.c perf bench: Add a multi-threaded synthesize benchmark 2020-04-30 10:48:25 -03:00