Messages in this thread | | | Subject | Re: [PATCH 2/2] posix-cpu-timers: remove tasklist_lock where we can | From | Peter Zijlstra <> | Date | Fri, 12 Jun 2009 09:11:17 +0200 |
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On Fri, 2009-06-12 at 08:49 +0200, Stanislaw Gruszka wrote: > tasklist_lock is not needed to protect find_task_by_vpid() nor > thread_group_leader() nor same_thread_group() , use rcu_read_lock() instead.
Aside from not being strictly needed, one can sometimes require a tasklist_lock reader to ensure nothing changes, however since the code is racy in that regard anyway, this looks good.
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com> > --- > kernel/posix-cpu-timers.c | 8 ++++---- > 1 files changed, 4 insertions(+), 4 deletions(-) > > diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c > index bece7c0..1d9cdf3 100644 > --- a/kernel/posix-cpu-timers.c > +++ b/kernel/posix-cpu-timers.c > @@ -37,13 +37,13 @@ static int check_clock(const clockid_t which_clock) > if (pid == 0) > return 0; > > - read_lock(&tasklist_lock); > + rcu_read_lock(); > p = find_task_by_vpid(pid); > if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ? > same_thread_group(p, current) : thread_group_leader(p))) { > error = -EINVAL; > } > - read_unlock(&tasklist_lock); > + rcu_read_lock(); > > return error; > } > @@ -398,7 +398,7 @@ int posix_cpu_timer_create(struct k_itimer *new_timer) > new_timer->it.cpu.incr.sched = 0; > new_timer->it.cpu.expires.sched = 0; > > - read_lock(&tasklist_lock); > + rcu_read_lock(); > if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) { > if (pid == 0) { > p = current; > @@ -422,7 +422,7 @@ int posix_cpu_timer_create(struct k_itimer *new_timer) > } else { > ret = -EINVAL; > } > - read_unlock(&tasklist_lock); > + rcu_read_unlock(); > > return ret; > }
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