3.2.94-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Mikulas Patocka <mpatocka@xxxxxxxxxx>
commit f9c79bc05a2a91f4fba8bfd653579e066714b1ec upstream.
The function flush_signals clears all pending signals for the process. It
may be used by kernel threads when we need to prepare a kernel thread for
responding to signals. However using this function for an userspaces
processes is incorrect - clearing signals without the program expecting it
can cause misbehavior.
The raid1 and raid5 code uses flush_signals in its request routine because
it wants to prepare for an interruptible wait. This patch drops
flush_signals and uses sigprocmask instead to block all signals (including
SIGKILL) around the schedule() call. The signals are not lost, but the
schedule() call won't respond to them.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Acked-by: NeilBrown <neilb@xxxxxxxx>
Signed-off-by: Shaohua Li <shli@xxxxxx>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -875,13 +875,16 @@ static void make_request(struct mddev *m
*/
DEFINE_WAIT(w);
for (;;) {
- flush_signals(current);
+ sigset_t full, old;
prepare_to_wait(&conf->wait_barrier,
&w, TASK_INTERRUPTIBLE);
if (bio->bi_sector + bio->bi_size/512 <= mddev->suspend_lo ||
bio->bi_sector >= mddev->suspend_hi)
break;
+ sigfillset(&full);
+ sigprocmask(SIG_BLOCK, &full, &old);
schedule();
+ sigprocmask(SIG_SETMASK, &old, NULL);
}
finish_wait(&conf->wait_barrier, &w);
}
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -3823,12 +3823,16 @@ static void make_request(struct mddev *m
* userspace, we want an interruptible
* wait.
*/
- flush_signals(current);
prepare_to_wait(&conf->wait_for_overlap,
&w, TASK_INTERRUPTIBLE);
if (logical_sector >= mddev->suspend_lo &&
- logical_sector < mddev->suspend_hi)
+ logical_sector < mddev->suspend_hi) {
+ sigset_t full, old;
+ sigfillset(&full);
+ sigprocmask(SIG_BLOCK, &full, &old);
schedule();
+ sigprocmask(SIG_SETMASK, &old, NULL);
+ }
goto retry;
}