Commit 40c7fd3f authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Jens Axboe
Browse files

block: Fix sys_ioprio_set(.which=IOPRIO_WHO_PGRP) task iteration 



do_each_pid_thread() { } while_each_pid_thread() is a double loop and
thus break doesn't work as expected. Also, it should be used under
tasklist_lock because otherwise we can race against change_pid() for
PGID/SID.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/YG7Q5C4Rb5dx5GFx@hirez.programming.kicks-ass.net


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 3212135a

block/ioprio.c

+9 −2
Original line number Diff line number Diff line
@@ -119,11 +119,17 @@ SYSCALL_DEFINE3(ioprio_set, int, which, int, who, int, ioprio) 
				pgrp = task_pgrp(current);

			else

				pgrp = find_vpid(who);



			read_lock(&tasklist_lock);

			do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {

				ret = set_task_ioprio(p, ioprio);

				if (ret)

					break;

				if (ret) {

					read_unlock(&tasklist_lock);

					goto out;

				}

			} while_each_pid_thread(pgrp, PIDTYPE_PGID, p);

			read_unlock(&tasklist_lock);



			break;

		case IOPRIO_WHO_USER:

			uid = make_kuid(current_user_ns(), who);
@@ -153,6 +159,7 @@ SYSCALL_DEFINE3(ioprio_set, int, which, int, who, int, ioprio) 
			ret = -EINVAL;

	}



out:

	rcu_read_unlock();

	return ret;

}