The patch titled
POSIX timers RCU optimization fix for clock_gettime
has been added to the -mm tree. Its filename is
posix-timers-rcu-optimization-for-clock_gettime-fix.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: POSIX timers RCU optimization fix for clock_gettime
From: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
Fixes an exit()/posix_cpu_clock_get() race spotted by Oleg Nesterov.
Solution is to move the p->signal check under the tasklist_lock.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: john stultz <johnstul@xxxxxxxxxx>
Cc: Roman Zippel <zippel@xxxxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/posix-cpu-timers.c | 9 ++++++---
1 files changed, 6 insertions(+), 3 deletions(-)
diff -puN kernel/posix-cpu-timers.c~posix-timers-rcu-optimization-for-clock_gettime-fix kernel/posix-cpu-timers.c
--- a/kernel/posix-cpu-timers.c~posix-timers-rcu-optimization-for-clock_gettime-fix
+++ a/kernel/posix-cpu-timers.c
@@ -312,10 +312,13 @@ int posix_cpu_clock_get(const clockid_t
error = cpu_clock_sample(which_clock,
p, &rtn);
}
- } else if (p->tgid == pid && p->signal) {
+ } else {
read_lock(&tasklist_lock);
- error = cpu_clock_sample_group(which_clock,
- p, &rtn);
+ if (p->tgid == pid && p->signal) {
+ error =
+ cpu_clock_sample_group(which_clock,
+ p, &rtn);
+ }
read_unlock(&tasklist_lock);
}
}
_
Patches currently in -mm which might be from paulmck@xxxxxxxxxxxxxxxxxx are
git-block.patch
add-an-rcu-version-of-list-splicing.patch
add-an-rcu-version-of-list-splicing-fix.patch
ipmi-fix-some-rcu-problems.patch
change-constant-zero-to-notify_done-in-ratelimit_handler.patch
posix-timers-rcu-optimization-for-clock_gettime.patch
posix-timers-rcu-optimization-for-clock_gettime-fix.patch
-
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