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md/raid10: add rcu protection in raid10_status. 

mirrors[].rdev can become NULL at any point unless:
 - a counted reference is held
 - ->reconfig_mutex is held, or
 - rcu_read_lock() is held

raid10_status holds none of these.  So add rcu_read_lock()
protection.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
hifive-unleashed-5.1
NeilBrown 2016-06-02 16:19:52 +10:00 committed by Shaohua Li
parent 83f1261f5e
commit d44b0a928f
1 changed files with 6 additions and 4 deletions
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10
drivers/md/raid10.c
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@ -1495,10 +1495,12 @@ static void raid10_status(struct seq_file *seq, struct mddev *mddev)
}
seq_printf(seq, " [%d/%d] [", conf->geo.raid_disks,
conf->geo.raid_disks - mddev->degraded);
for (i = 0; i < conf->geo.raid_disks; i++)
seq_printf(seq, "%s",
conf->mirrors[i].rdev &&
test_bit(In_sync, &conf->mirrors[i].rdev->flags) ? "U" : "_");
rcu_read_lock();
for (i = 0; i < conf->geo.raid_disks; i++) {
struct md_rdev *rdev = rcu_dereference(conf->mirrors[i].rdev);
seq_printf(seq, "%s", rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_");
}
rcu_read_unlock();
seq_printf(seq, "]");
}