Messages in this thread Patch in this message | | | From | Ben Hutchings <> | Date | Mon, 09 Oct 2017 13:30:34 +0100 | Subject | [PATCH 3.2 10/74] md: don't use flush_signals in userspace processes |
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3.2.94-rc1 review patch. If anyone has any objections, please let me know.
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From: Mikulas Patocka <mpatocka@redhat.com>
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@redhat.com> Acked-by: NeilBrown <neilb@suse.com> Signed-off-by: Shaohua Li <shli@fb.com> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- --- 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; }
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