| Date | Mon, 26 Aug 2019 18:32:05 +0200 | From | Frederic Weisbecker <> | Subject | Re: [patch V2 28/38] posix-cpu-timers: Restructure expiry array |
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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...).
[...]
> @@ -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.
> > if (WARN_ON_ONCE(clkid >= CPUCLOCK_SCHED)) > return; > @@ -1207,8 +1213,8 @@ void set_process_cpu_timer(struct task_s > * Update expiration cache if this is the earliest timer. CPUCLOCK_PROF > * expiry cache is also used by RLIMIT_CPU!. > */ > - if (expires_gt(*expiry, *newval)) > - *expiry = *newval; > + if (expires_gt(*nextevt, *newval)) > + *nextevt = *newval; > > tick_dep_set_signal(tsk->signal, TICK_DEP_BIT_POSIX_TIMER); > } > >
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