Messages in this thread | | | Date | Thu, 22 Aug 2019 01:03:20 +0200 | From | Frederic Weisbecker <> | Subject | Re: [patch V2 01/38] posix-cpu-timers: Provide task validation functions |
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On Thu, Aug 22, 2019 at 12:33:56AM +0200, Frederic Weisbecker wrote: > On Wed, Aug 21, 2019 at 09:08:48PM +0200, Thomas Gleixner wrote: > > The code contains three slightly different copies of validating whether a > > given clock resolves to a valid task and whether the current caller has > > permissions to access it. > > > > Create central functions. Replace check_clock() as a first step and rename > > it to something sensible. > > > > Signed-off-by: Thomas Gleixner <tglx@linutronix.de> > > --- > > kernel/time/posix-cpu-timers.c | 65 +++++++++++++++++++++++++++-------------- > > 1 file changed, 44 insertions(+), 21 deletions(-) > > > > --- a/kernel/time/posix-cpu-timers.c > > +++ b/kernel/time/posix-cpu-timers.c > > @@ -35,27 +35,52 @@ void update_rlimit_cpu(struct task_struc > > spin_unlock_irq(&task->sighand->siglock); > > } > > > > -static int check_clock(const clockid_t which_clock) > > +/* > > + * Functions for validating access to tasks. > > + */ > > +static struct task_struct *lookup_task(const pid_t pid, bool thread) > > { > > - int error = 0; > > struct task_struct *p; > > - const pid_t pid = CPUCLOCK_PID(which_clock); > > > > - if (CPUCLOCK_WHICH(which_clock) >= CPUCLOCK_MAX) > > - return -EINVAL; > > + if (!pid) > > + return thread ? current : current->group_leader; > > > > - if (pid == 0) > > - return 0; > > + p = find_task_by_vpid(pid); > > + if (!p || p == current) > > + return p; > > What if (p == current && !thread && !has_group_leader_pid(p)) ?
Ah looking at the next patch, posix_cpu_clock_get_task() and posix_cpu_clock_getres() had different ad-hoc checks for this specific case.
clock_getres() used to return -EINVAL while clock_get() doesn't care. They certainly should agree in their behaviour. I'm not sure which one is correct. It probably doesn't matter much.
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