2170017a1c
Make the one-time initialization in av_get_cpu_flags() thread-safe. The
static variables |flags|, |cpuflags_mask|, and |checked| in
libavutil/cpu.c are read and written using normal load and store
operations. These are considered as data races. The fix is to use atomic
load and store operations.
Remove the |checked| variable because the invalid value of -1 for
|flags| can be used to indicate the same condition. Rename |flags| to
|cpu_flags| and move it to file scope.
The fix can be verified by running the libavutil/tests/cpu_init.c test
program under ThreadSanitizer:
./configure --toolchain=clang-tsan
make libavutil/tests/cpu_init
libavutil/tests/cpu_init
There should be no warnings from ThreadSanitizer.
Co-author: Dmitry Vyukov of Google, who suggested the data race fix.
Signed-off-by: Wan-Teh Chang <wtc@google.com>
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| .. | ||
| .gitignore | ||
| adler32.c | ||
| aes.c | ||
| avstring.c | ||
| base64.c | ||
| blowfish.c | ||
| cpu.c | ||
| cpu_init.c | ||
| crc.c | ||
| des.c | ||
| eval.c | ||
| fifo.c | ||
| float_dsp.c | ||
| hmac.c | ||
| lfg.c | ||
| lls.c | ||
| md5.c | ||
| opt.c | ||
| parseutils.c | ||
| sha.c | ||
| tree.c | ||
| xtea.c | ||