lkml.org 
[lkml]   [2024]   [Apr]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Date
    SubjectRe: [patch V2 07/50] posix-cpu-timers: Split up posix_cpu_timer_get()
    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();
    > }
    >

    \
     
     \ /
      Last update: 2024-04-12 20:49    [W:4.035 / U:0.356 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site