diff options
Diffstat (limited to 'kernel/time')
| -rw-r--r-- | kernel/time/clocksource.c | 9 | ||||
| -rw-r--r-- | kernel/time/hrtimer.c | 2 | ||||
| -rw-r--r-- | kernel/time/posix-cpu-timers.c | 63 | ||||
| -rw-r--r-- | kernel/time/timekeeping.c | 4 | ||||
| -rw-r--r-- | kernel/time/timer.c | 13 |
5 files changed, 62 insertions, 29 deletions
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index 841b72f720e8..0d8fe8b8f727 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -217,7 +217,7 @@ static void clocksource_watchdog(unsigned long data) continue; /* Check the deviation from the watchdog clocksource. */ - if ((abs(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD)) { + if (abs64(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD) { pr_warn("timekeeping watchdog: Marking clocksource '%s' as unstable because the skew is too large:\n", cs->name); pr_warn(" '%s' wd_now: %llx wd_last: %llx mask: %llx\n", @@ -479,7 +479,7 @@ static u32 clocksource_max_adjustment(struct clocksource *cs) * return half the number of nanoseconds the hardware counter can technically * cover. This is done so that we can potentially detect problems caused by * delayed timers or bad hardware, which might result in time intervals that - * are larger then what the math used can handle without overflows. + * are larger than what the math used can handle without overflows. */ u64 clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cyc) { @@ -595,16 +595,15 @@ static void __clocksource_select(bool skipcur) */ static void clocksource_select(void) { - return __clocksource_select(false); + __clocksource_select(false); } static void clocksource_select_fallback(void) { - return __clocksource_select(true); + __clocksource_select(true); } #else /* !CONFIG_ARCH_USES_GETTIMEOFFSET */ - static inline void clocksource_select(void) { } static inline void clocksource_select_fallback(void) { } diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index 457a373e2181..435b8850dd80 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -59,7 +59,7 @@ /* * The timer bases: * - * There are more clockids then hrtimer bases. Thus, we index + * There are more clockids than hrtimer bases. Thus, we index * into the timer bases by the hrtimer_base_type enum. When trying * to reach a base using a clockid, hrtimer_clockid_to_base() * is used to convert from clockid to the proper hrtimer_base_type. diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c index 892e3dae0aac..f5e86d282d52 100644 --- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -249,7 +249,7 @@ void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times) * but barriers are not required because update_gt_cputime() * can handle concurrent updates. */ - WRITE_ONCE(cputimer->running, 1); + WRITE_ONCE(cputimer->running, true); } sample_cputime_atomic(times, &cputimer->cputime_atomic); } @@ -864,6 +864,13 @@ static void check_thread_timers(struct task_struct *tsk, unsigned long long expires; unsigned long soft; + /* + * If cputime_expires is zero, then there are no active + * per thread CPU timers. + */ + if (task_cputime_zero(&tsk->cputime_expires)) + return; + expires = check_timers_list(timers, firing, prof_ticks(tsk)); tsk_expires->prof_exp = expires_to_cputime(expires); @@ -911,7 +918,7 @@ static inline void stop_process_timers(struct signal_struct *sig) struct thread_group_cputimer *cputimer = &sig->cputimer; /* Turn off cputimer->running. This is done without locking. */ - WRITE_ONCE(cputimer->running, 0); + WRITE_ONCE(cputimer->running, false); } static u32 onecputick; @@ -962,6 +969,19 @@ static void check_process_timers(struct task_struct *tsk, unsigned long soft; /* + * If cputimer is not running, then there are no active + * process wide timers (POSIX 1.b, itimers, RLIMIT_CPU). + */ + if (!READ_ONCE(tsk->signal->cputimer.running)) + return; + + /* + * Signify that a thread is checking for process timers. + * Write access to this field is protected by the sighand lock. + */ + sig->cputimer.checking_timer = true; + + /* * Collect the current process totals. */ thread_group_cputimer(tsk, &cputime); @@ -1015,6 +1035,8 @@ static void check_process_timers(struct task_struct *tsk, sig->cputime_expires.sched_exp = sched_expires; if (task_cputime_zero(&sig->cputime_expires)) stop_process_timers(sig); + + sig->cputimer.checking_timer = false; } /* @@ -1117,24 +1139,33 @@ static inline int task_cputime_expired(const struct task_cputime *sample, static inline int fastpath_timer_check(struct task_struct *tsk) { struct signal_struct *sig; - cputime_t utime, stime; - - task_cputime(tsk, &utime, &stime); if (!task_cputime_zero(&tsk->cputime_expires)) { - struct task_cputime task_sample = { - .utime = utime, - .stime = stime, - .sum_exec_runtime = tsk->se.sum_exec_runtime - }; + struct task_cputime task_sample; + task_cputime(tsk, &task_sample.utime, &task_sample.stime); + task_sample.sum_exec_runtime = tsk->se.sum_exec_runtime; if (task_cputime_expired(&task_sample, &tsk->cputime_expires)) return 1; } sig = tsk->signal; - /* Check if cputimer is running. This is accessed without locking. */ - if (READ_ONCE(sig->cputimer.running)) { + /* + * Check if thread group timers expired when the cputimer is + * running and no other thread in the group is already checking + * for thread group cputimers. These fields are read without the + * sighand lock. However, this is fine because this is meant to + * be a fastpath heuristic to determine whether we should try to + * acquire the sighand lock to check/handle timers. + * + * In the worst case scenario, if 'running' or 'checking_timer' gets + * set but the current thread doesn't see the change yet, we'll wait + * until the next thread in the group gets a scheduler interrupt to + * handle the timer. This isn't an issue in practice because these + * types of delays with signals actually getting sent are expected. + */ + if (READ_ONCE(sig->cputimer.running) && + !READ_ONCE(sig->cputimer.checking_timer)) { struct task_cputime group_sample; sample_cputime_atomic(&group_sample, &sig->cputimer.cputime_atomic); @@ -1174,12 +1205,8 @@ void run_posix_cpu_timers(struct task_struct *tsk) * put them on the firing list. */ check_thread_timers(tsk, &firing); - /* - * If there are any active process wide timers (POSIX 1.b, itimers, - * RLIMIT_CPU) cputimer must be running. - */ - if (READ_ONCE(tsk->signal->cputimer.running)) - check_process_timers(tsk, &firing); + + check_process_timers(tsk, &firing); /* * We must release these locks before taking any timer's lock. diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 274ed5e88456..d50543101247 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1674,7 +1674,7 @@ static void timekeeping_adjust(struct timekeeper *tk, s64 offset) /** * accumulate_nsecs_to_secs - Accumulates nsecs into secs * - * Helper function that accumulates a the nsecs greater then a second + * Helper function that accumulates the nsecs greater than a second * from the xtime_nsec field to the xtime_secs field. * It also calls into the NTP code to handle leapsecond processing. * @@ -1726,7 +1726,7 @@ static cycle_t logarithmic_accumulation(struct timekeeper *tk, cycle_t offset, cycle_t interval = tk->cycle_interval << shift; u64 raw_nsecs; - /* If the offset is smaller then a shifted interval, do nothing */ + /* If the offset is smaller than a shifted interval, do nothing */ if (offset < interval) return offset; diff --git a/kernel/time/timer.c b/kernel/time/timer.c index 84190f02b521..74591ba9474f 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -461,10 +461,17 @@ void __timer_stats_timer_set_start_info(struct timer_list *timer, void *addr) static void timer_stats_account_timer(struct timer_list *timer) { - if (likely(!timer->start_site)) + void *site; + + /* + * start_site can be concurrently reset by + * timer_stats_timer_clear_start_info() + */ + site = READ_ONCE(timer->start_site); + if (likely(!site)) return; - timer_stats_update_stats(timer, timer->start_pid, timer->start_site, + timer_stats_update_stats(timer, timer->start_pid, site, timer->function, timer->start_comm, timer->flags); } @@ -867,7 +874,7 @@ unsigned long apply_slack(struct timer_list *timer, unsigned long expires) if (mask == 0) return expires; - bit = find_last_bit(&mask, BITS_PER_LONG); + bit = __fls(mask); mask = (1UL << bit) - 1; |