The patch titled
k_getrusage: don't take rcu_read_lock()
has been added to the -mm tree. Its filename is
k_getrusage-dont-take-rcu_read_lock.patch
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The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: k_getrusage: don't take rcu_read_lock()
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Just a trivial example, more to come.
k_getrusage() holds rcu_read_lock() because it was previously required by
lock_task_sighand(). Unneeded now.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/sys.c | 7 +------
1 file changed, 1 insertion(+), 6 deletions(-)
diff -puN kernel/sys.c~k_getrusage-dont-take-rcu_read_lock kernel/sys.c
--- a/kernel/sys.c~k_getrusage-dont-take-rcu_read_lock
+++ a/kernel/sys.c
@@ -1566,11 +1566,8 @@ static void k_getrusage(struct task_stru
goto out;
}
- rcu_read_lock();
- if (!lock_task_sighand(p, &flags)) {
- rcu_read_unlock();
+ if (!lock_task_sighand(p, &flags))
return;
- }
switch (who) {
case RUSAGE_BOTH:
@@ -1606,9 +1603,7 @@ static void k_getrusage(struct task_stru
default:
BUG();
}
-
unlock_task_sighand(p, &flags);
- rcu_read_unlock();
out:
cputime_to_timeval(utime, &r->ru_utime);
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
kthread-synchronization-issues.patch
kthread-add-a-missing-memory-barrier-to-kthread_stop.patch
kthread-call-wake_up_process-without-the-lock-being-held.patch
mmap_region-cleanup-the-final-vma_merge-related-code.patch
remove-unused-variable-from-send_signal.patch
turn-legacy_queue-macro-into-static-inline-function.patch
consolidate-checking-for-ignored-legacy-signals.patch
consolidate-checking-for-ignored-legacy-signals-simplify.patch
signals-do_signal_stop-use-signal_group_exit.patch
signals-do_group_exit-use-signal_group_exit-more-consistently.patch
lock_task_sighand-add-rcu-lock-unlock.patch
k_getrusage-dont-take-rcu_read_lock.patch
do_task_stat-dont-take-rcu_read_lock.patch
workqueues-shrink-cpu_populated_map-when-cpu-dies.patch
workqueues-shrink-cpu_populated_map-when-cpu-dies-fix.patch
cleanup_workqueue_thread-remove-the-unneeded-cpu-parameter.patch
simplify-cpu_hotplug_begin-put_online_cpus.patch
timers-simplify-lockdep-stuff.patch
hrtimers-simplify-lockdep-stuff.patch
kill-double_spin_lock.patch
redo-locking-of-tty-pgrp.patch
procfs-task-exe-symlink.patch
procfs-task-exe-symlink-fix.patch
procfs-task-exe-symlink-fix-2.patch
free_pidmap-turn-it-into-free_pidmapstruct-upid.patch
put_pid-make-sure-we-dont-free-the-live-pid.patch
-
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