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sched: Check for zero sleep time and yield CPU if

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necessary

Signed-off-by: Huang Qi <huangqi3@xiaomi.com>
This commit is contained in:
Huang Qi 2023-11-06 12:22:27 +08:00 committed by Xiang Xiao
parent d410a6e1a6
commit 0995e17927
1 changed files with 18 additions and 0 deletions
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18
sched/signal/sig_nanosleep.c
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@ -103,6 +103,24 @@ int nxsig_nanosleep(FAR const struct timespec *rqtp,
return -EINVAL;
}
/* If rqtp is zero, yield CPU and return
* Notice: The behavior of sleep(0) is not defined in POSIX, so there are
* different implementations:
* 1. In Linux, nanosleep(0) will call schedule() to yield CPU:
* https://elixir.bootlin.com/linux/latest/source/kernel/time/
* hrtimer.c#L2038
* 2. In BSD, nanosleep(0) will return immediately:
* https://github.com/freebsd/freebsd-src/blob/
* 475fa89800086718bd9249fd4dc3f862549f1f78/crypto/openssh/
* openbsd-compat/bsd-misc.c#L243
*/
if (rqtp->tv_sec == 0 && rqtp->tv_nsec == 0)
{
sched_yield();
return OK;
}
/* Get the start time of the wait. Interrupts are disabled to prevent
* timer interrupts while we do tick-related calculations before and
* after the wait.