diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2023-04-25 20:49:14 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2023-06-18 22:41:50 +0200 |
| commit | 65cade468dee537885b51897ba41ba05a4dcf6ca (patch) | |
| tree | 8d1c10f627b55b8e4bb70218d70fc3488346b0d1 /kernel/time/posix-timers.c | |
| parent | a86e9284336729a8f79a65371eacd0c1c7fae142 (diff) | |
posix-timers: Document sys_clock_getoverrun()
Document the syscall in detail and with coherent sentences.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20230425183313.462051641@linutronix.de
Diffstat (limited to 'kernel/time/posix-timers.c')
| -rw-r--r-- | kernel/time/posix-timers.c | 25 |
1 files changed, 17 insertions, 8 deletions
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c index e1af74ca80ab..191ecf59cb98 100644 --- a/kernel/time/posix-timers.c +++ b/kernel/time/posix-timers.c @@ -783,14 +783,23 @@ SYSCALL_DEFINE2(timer_gettime32, timer_t, timer_id, #endif -/* - * Get the number of overruns of a POSIX.1b interval timer. This is to - * be the overrun of the timer last delivered. At the same time we are - * accumulating overruns on the next timer. The overrun is frozen when - * the signal is delivered, either at the notify time (if the info block - * is not queued) or at the actual delivery time (as we are informed by - * the call back to posixtimer_rearm(). So all we need to do is - * to pick up the frozen overrun. +/** + * sys_timer_getoverrun - Get the number of overruns of a POSIX.1b interval timer + * @timer_id: The timer ID which identifies the timer + * + * The "overrun count" of a timer is one plus the number of expiration + * intervals which have elapsed between the first expiry, which queues the + * signal and the actual signal delivery. On signal delivery the "overrun + * count" is calculated and cached, so it can be returned directly here. + * + * As this is relative to the last queued signal the returned overrun count + * is meaningless outside of the signal delivery path and even there it + * does not accurately reflect the current state when user space evaluates + * it. + * + * Returns: + * -EINVAL @timer_id is invalid + * 1..INT_MAX The number of overruns related to the last delivered signal */ SYSCALL_DEFINE1(timer_getoverrun, timer_t, timer_id) { |