use futex directly instead of via syscall on OpenBSD #1621
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sprunk
reviewed
Jul 27, 2024
rts/System/Platform/Linux/Futex.cpp
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| syscall(SYS_futex, &mtx, FUTEX_WAIT_PRIVATE, 2, NULL, NULL, 0); | ||
| #else | ||
| futex(&mtx, FUTEX_WAIT, 2, NULL, NULL); |
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not _PRIVATE on the FIUTEX constant?
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I didn't use _PRIVATE because it's not documented in our man page, but I see that these constants are also defined in sys/futex.h. I'll do a build with the _PRIVATE parts and if that works, I'll change it!
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changed it to _PRIVATE futex flags
sprunk
approved these changes
Jul 31, 2024
sprunk
reviewed
Jul 31, 2024
rts/System/Platform/Linux/Futex.cpp
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Comment on lines
36
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| #ifndef __OpenBSD__ | ||
| syscall(SYS_futex, &mtx, FUTEX_WAIT_PRIVATE, 2, NULL, NULL, 0); | ||
| #else | ||
| futex(&mtx, FUTEX_WAIT_PRIVATE, 2, NULL, NULL); | ||
| #endif |
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Perhaps this pattern could be extracted to a function? So somewhere above there would be
static inline void do_futex (uint32_t *mtx, uint32_t value)
{
#ifndef __OpenBSD__
syscall(SYS_futex, mtx, FUTEX_WAIT_PRIVATE, value, NULL, NULL, 0);
#else
futex(mtx, FUTEX_WAIT_PRIVATE, value, NULL, NULL);
#endif
}And this would become just
Suggested change
| #ifndef __OpenBSD__ | |
| syscall(SYS_futex, &mtx, FUTEX_WAIT_PRIVATE, 2, NULL, NULL, 0); | |
| #else | |
| futex(&mtx, FUTEX_WAIT_PRIVATE, 2, NULL, NULL); | |
| #endif | |
| do_futex(&mtx, 2); |
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that makes sense indeed. Will be easier to read/maintain. I'll rebase to do it this way
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This is necessary for building on OpenBSD (and currently used in the OpenBSD port of recoil). syscall entry point was removed from OpenBSD in 2023 for security reasons and the recommended way is use of the specific syscall as in this diff.