On Mon, 26 Aug 2019, Frederic Weisbecker wrote: > On Wed, Aug 21, 2019 at 09:09:15PM +0200, Thomas Gleixner wrote: > > /** > > - * task_cputimers_expired - Compare two task_cputime entities. > > + * task_cputimers_expired - Check whether posix CPU timers are expired > > * > > * @samples: Array of current samples for the CPUCLOCK clocks > > - * @expiries: Array of expiry values for the CPUCLOCK clocks > > + * @pct: Pointer to a posix_cputimers container > > * > > - * Returns true if any mmember of @samples is greater than the > > corresponding > > - * member of @expiries if that member is non zero. False otherwise > > + * Returns true if any member of @samples is greater than the corresponding > > + * member of @pct->bases[CLK].nextevt. False otherwise > > */ > > -static inline bool task_cputimers_expired(const u64 *sample, const u64 > > *expiries) > > +static inline bool > > +task_cputimers_expired(const u64 *sample, struct posix_cputimers *pct) > > { > > int i; > > > > for (i = 0; i < CPUCLOCK_MAX; i++) { > > - if (expiries[i] && sample[i] >= expiries[i]) > > + if (sample[i] >= pct->bases[i].nextevt) > > You may have false positive here if you don't check if pct->bases[i].nextevt > is 0. Probably no big deal by the end of the series since you change that 0 > for KTIME_MAX later but right now it might hurt bisection with performance > issues (locking sighand at every tick...).
Hrm. That should have stayed until the patch which removes that 0 state > [...] > > > @@ -1176,7 +1182,7 @@ void run_posix_cpu_timers(void) > > void set_process_cpu_timer(struct task_struct *tsk, unsigned int clkid, > > u64 *newval, u64 *oldval) > > { > > - u64 now, *expiry = tsk->signal->posix_cputimers.expiries + clkid; > > + u64 now, *nextevt = &tsk->signal->posix_cputimers.bases[clkid].nextevt; > > You're dereferencing the pointer before checking clkid sanity below. Urgh. Yes. Thanks, tglx