From: "Eric W. Biederman" <ebiederm@xmission.com>
To: Thomas Flexing <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
Anna-Maria Behnsen <anna-maria@linutronix.de>,
Frederic Weisbecker <frederic@kernel.org>,
John Stultz <jstultz@google.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>, Stephen Boyd <sboyd@kernel.org>,
Oleg Nesterov <oleg@redhat.com>
Subject: Re: [patch V2 07/50] posix-cpu-timers: Split up posix_cpu_timer_get()
Date: Fri, 12 Apr 2024 13:25:01 -0500 [thread overview]
Message-ID: <87mspyxwua.fsf@email.froward.int.ebiederm.org> (raw)
In-Reply-To: <20240410165551.376994018@linutronix.de> (Thomas Gleixner's message of "Thu, 11 Apr 2024 00:46:24 +0200 (CEST)")
Thomas Gleixner <tglx@linutronix.de> writes:
> In preparation for addressing issues in the timer_get() and timer_set()
> functions of posix CPU timers.
To see that this was safe I had to lookup and see that
cpu_timer_getexpires is a truly trivial function.
static inline u64 cpu_timer_getexpires(struct cpu_timer *ctmr)
{
return ctmr->node.expires;
}
I am a bit confused by the purpose of this function in
posix-cpu-timers.c. In some places this helper is used (like below),
and in other places like bump_cpu_timer the expires member is
accessed directly.
It isn't really a problem, but it is something that might be
worth making consistent in the code to make it easier to read.
Eric
> No functional change.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
> V2: Split out into new patch to make review simpler - Frederic
> ---
> kernel/time/posix-cpu-timers.c | 51 +++++++++++++++++++----------------------
> 1 file changed, 24 insertions(+), 27 deletions(-)
>
> --- a/kernel/time/posix-cpu-timers.c
> +++ b/kernel/time/posix-cpu-timers.c
> @@ -785,33 +785,9 @@ static int posix_cpu_timer_set(struct k_
> return ret;
> }
>
> -static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec64 *itp)
> +static void __posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec64 *itp, u64 now)
> {
> - clockid_t clkid = CPUCLOCK_WHICH(timer->it_clock);
> - struct cpu_timer *ctmr = &timer->it.cpu;
> - u64 now, expires = cpu_timer_getexpires(ctmr);
> - struct task_struct *p;
> -
> - rcu_read_lock();
> - p = cpu_timer_task_rcu(timer);
> - if (!p)
> - goto out;
> -
> - /*
> - * Easy part: convert the reload time.
> - */
> - itp->it_interval = ktime_to_timespec64(timer->it_interval);
> -
> - if (!expires)
> - goto out;
> -
> - /*
> - * Sample the clock to take the difference with the expiry time.
> - */
> - if (CPUCLOCK_PERTHREAD(timer->it_clock))
> - now = cpu_clock_sample(clkid, p);
> - else
> - now = cpu_clock_sample_group(clkid, p, false);
> + u64 expires = cpu_timer_getexpires(&timer->it.cpu);
>
> if (now < expires) {
> itp->it_value = ns_to_timespec64(expires - now);
> @@ -823,7 +799,28 @@ static void posix_cpu_timer_get(struct k
> itp->it_value.tv_nsec = 1;
> itp->it_value.tv_sec = 0;
> }
> -out:
> +}
> +
> +static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec64 *itp)
> +{
> + clockid_t clkid = CPUCLOCK_WHICH(timer->it_clock);
> + struct task_struct *p;
> + u64 now;
> +
> + rcu_read_lock();
> + p = cpu_timer_task_rcu(timer);
> + if (p) {
> + itp->it_interval = ktime_to_timespec64(timer->it_interval);
> +
> + if (cpu_timer_getexpires(&timer->it.cpu)) {
> + if (CPUCLOCK_PERTHREAD(timer->it_clock))
> + now = cpu_clock_sample(clkid, p);
> + else
> + now = cpu_clock_sample_group(clkid, p, false);
> +
> + __posix_cpu_timer_get(timer, itp, now);
> + }
> + }
> rcu_read_unlock();
> }
>
next prev parent reply other threads:[~2024-04-12 18:49 UTC|newest]
Thread overview: 91+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-10 22:46 [patch V2 00/50] posix-timers: Cure inconsistencies and the SIG_IGN mess Thomas Gleixner
2024-04-10 22:46 ` [patch V2 01/50] selftests/timers/posix_timers: Simplify error handling Thomas Gleixner
2024-04-12 7:35 ` Anna-Maria Behnsen
2024-04-10 22:46 ` [patch V2 02/50] selftests/timers/posix_timers: Add SIG_IGN test Thomas Gleixner
2024-04-10 22:46 ` [patch V2 03/50] selftests/timers/posix_timers: Validate signal rules Thomas Gleixner
2024-04-10 22:46 ` [patch V2 04/50] selftests/timers/posix-timers: Validate SIGEV_NONE Thomas Gleixner
2024-04-10 22:46 ` [patch V2 05/50] selftests/timers/posix-timers: Validate timer_gettime() Thomas Gleixner
2024-04-10 22:46 ` [patch V2 06/50] selftests/timers/posix-timers: Validate overrun after unblock Thomas Gleixner
2024-04-10 22:46 ` [patch V2 07/50] posix-cpu-timers: Split up posix_cpu_timer_get() Thomas Gleixner
2024-04-12 7:35 ` Anna-Maria Behnsen
2024-04-12 18:25 ` Eric W. Biederman [this message]
2024-04-12 19:48 ` Thomas Gleixner
2024-04-16 14:44 ` Oleg Nesterov
2024-04-17 9:21 ` Anna-Maria Behnsen
2024-04-17 11:08 ` Oleg Nesterov
2024-04-17 20:33 ` Frederic Weisbecker
2024-04-10 22:46 ` [patch V2 08/50] posix-cpu-timers: Save interval only for armed timers Thomas Gleixner
2024-04-11 14:25 ` Anna-Maria Behnsen
2024-04-11 22:00 ` Thomas Gleixner
2024-04-10 22:46 ` [patch V2 09/50] posix-cpu-timers: Handle interval timers correctly in timer_get() Thomas Gleixner
2024-04-17 22:50 ` Frederic Weisbecker
2024-04-10 22:46 ` [patch V2 10/50] posix-cpu-timers: Handle SIGEV_NONE " Thomas Gleixner
2024-04-12 18:40 ` Eric W. Biederman
2024-04-12 19:49 ` Thomas Gleixner
2024-04-10 22:46 ` [patch V2 11/50] posix-cpu-timers: Handle SIGEV_NONE timers correctly in timer_set() Thomas Gleixner
2024-04-11 15:48 ` Anna-Maria Behnsen
2024-04-11 22:02 ` Thomas Gleixner
2024-04-17 23:04 ` Frederic Weisbecker
2024-04-10 22:46 ` [patch V2 12/50] posix-cpu-timers: Replace old expiry retrieval in posix_cpu_timer_set() Thomas Gleixner
2024-04-15 14:03 ` Anna-Maria Behnsen
2024-04-10 22:46 ` [patch V2 13/50] posix-cpu-timers: Do not arm SIGEV_NONE timers Thomas Gleixner
2024-04-15 14:03 ` Anna-Maria Behnsen
2024-04-10 22:46 ` [patch V2 14/50] posix-cpu-timers: Use @now instead of @val for clarity Thomas Gleixner
2024-04-10 22:46 ` [patch V2 15/50] posix-cpu-timers: Remove incorrect comment in posix_cpu_timer_set() Thomas Gleixner
2024-04-10 22:46 ` [patch V2 16/50] posix-cpu-timers: Simplify posix_cpu_timer_set() Thomas Gleixner
2024-04-15 15:28 ` Anna-Maria Behnsen
2024-04-10 22:46 ` [patch V2 17/50] posix-timers: Retrieve interval in common timer_settime() code Thomas Gleixner
2024-04-15 15:43 ` Anna-Maria Behnsen
2024-04-10 22:46 ` [patch V2 18/50] posix-timers: Clear overrun in common_timer_set() Thomas Gleixner
2024-04-10 22:46 ` [patch V2 19/50] posix-timers: Convert timer list to hlist Thomas Gleixner
2024-04-10 22:46 ` [patch V2 20/50] posix-timers: Consolidate timer setup Thomas Gleixner
2024-04-16 16:12 ` Anna-Maria Behnsen
2024-04-23 19:38 ` Thomas Gleixner
2024-04-10 22:46 ` [patch V2 21/50] posix-cpu-timers: Make k_itimer::it_active consistent Thomas Gleixner
2024-04-17 10:11 ` Anna-Maria Behnsen
2024-04-10 22:46 ` [patch V2 22/50] posix-timers: Consolidate signal queueing Thomas Gleixner
2024-04-10 22:46 ` [patch V2 23/50] signal: Remove task argument from dequeue_signal() Thomas Gleixner
2024-04-18 14:18 ` Oleg Nesterov
2024-04-10 22:46 ` [patch V2 24/50] signal: Replace BUG_ON()s Thomas Gleixner
2024-04-18 14:37 ` Oleg Nesterov
2024-04-10 22:46 ` [patch V2 25/50] signal: Confine POSIX_TIMERS properly Thomas Gleixner
2024-04-17 12:09 ` Anna-Maria Behnsen
2024-04-18 15:23 ` Oleg Nesterov
2024-04-19 5:42 ` Thomas Gleixner
2024-04-10 22:46 ` [patch V2 26/50] signal: Get rid of resched_timer logic Thomas Gleixner
2024-04-18 16:38 ` Oleg Nesterov
2024-04-18 18:18 ` Oleg Nesterov
2024-04-19 11:06 ` Oleg Nesterov
2024-04-23 21:18 ` Thomas Gleixner
2024-04-24 1:48 ` Thomas Gleixner
2024-04-25 7:22 ` Andrei Vagin
2024-04-10 22:46 ` [patch V2 27/50] posix-timers: Cure si_sys_private race Thomas Gleixner
2024-04-10 22:47 ` [patch V2 28/50] signal: Allow POSIX timer signals to be dropped Thomas Gleixner
2024-04-10 22:47 ` [patch V2 29/50] posix-timers: Drop signal if timer has been deleted or reprogrammed Thomas Gleixner
2024-04-10 22:47 ` [patch V2 30/50] posix-timers: Rename k_itimer::it_requeue_pending Thomas Gleixner
2024-04-10 22:47 ` [patch V2 31/50] posix-timers: Add proper state tracking Thomas Gleixner
2024-04-17 13:40 ` Anna-Maria Behnsen
2024-04-10 22:47 ` [patch V2 32/50] posix-timers: Make signal delivery consistent Thomas Gleixner
2024-04-18 10:29 ` Anna-Maria Behnsen
2024-04-10 22:47 ` [patch V2 33/50] posix-timers: Make signal overrun accounting sensible Thomas Gleixner
2024-04-10 22:47 ` [patch V2 34/50] posix-cpu-timers: Use dedicated flag for CPU timer nanosleep Thomas Gleixner
2024-04-10 22:47 ` [patch V2 35/50] posix-timers: Add a refcount to struct k_itimer Thomas Gleixner
2024-04-10 22:47 ` [patch V2 36/50] signal: Split up __sigqueue_alloc() Thomas Gleixner
2024-04-10 22:47 ` [patch V2 37/50] signal: Provide posixtimer_sigqueue_init() Thomas Gleixner
2024-04-10 22:47 ` [patch V2 38/50] signal: Add sys_private_ptr to siginfo::_sifields::_timer Thomas Gleixner
2024-04-10 22:47 ` [patch V2 39/50] posix-timers: Store PID type in the timer Thomas Gleixner
2024-04-10 22:47 ` [patch V2 40/50] signal: Refactor send_sigqueue() Thomas Gleixner
2024-04-10 22:47 ` [patch V2 41/50] posix-timers: Embed sigqueue in struct k_itimer Thomas Gleixner
2024-04-10 22:47 ` [patch V2 42/50] signal: Cleanup unused posix-timer leftovers Thomas Gleixner
2024-04-10 22:47 ` [patch V2 43/50] signal: Add task argument to flush_sigqueue_mask() Thomas Gleixner
2024-04-10 22:47 ` [patch V2 44/50] signal: Provide ignored_posix_timers list Thomas Gleixner
2024-04-10 22:47 ` [patch V2 45/50] posix-timers: Handle ignored list on delete and exit Thomas Gleixner
2024-04-10 22:47 ` [patch V2 46/50] signal: Handle ignored signals in do_sigaction(action != SIG_IGN) Thomas Gleixner
2024-04-10 22:47 ` [patch V2 47/50] signal: Queue ignored posixtimers on ignore list Thomas Gleixner
2024-04-10 22:47 ` [patch V2 48/50] posix-timers: Cleanup SIG_IGN workaround leftovers Thomas Gleixner
2024-04-10 22:47 ` [patch V2 49/50] alarmtimers: Remove the throttle mechanism from alarm_forward_now() Thomas Gleixner
2024-04-10 22:47 ` [patch V2 50/50] alarmtimers: Remove return value from alarm functions Thomas Gleixner
2024-04-15 12:30 ` [PATCH] posix-timers: Handle returned errors poperly in [i]timer_delete() Anna-Maria Behnsen
2024-04-15 13:00 ` Oleg Nesterov
2024-04-15 14:15 ` Anna-Maria Behnsen
2024-04-15 16:27 ` Oleg Nesterov
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