Commit 88ec4749 authored Nov 16, 2018 by Olof Johansson Committed by Patrick Daly Mar 08, 2019

kernel/sched/psi.c: simplify cgroup_move_task()

The existing code triggered an invalid warning about 'rq' possibly being
used uninitialized.  Instead of doing the silly warning suppression by
initializa it to NULL, refactor the code to bail out early instead.

Warning was:

  kernel/sched/psi.c: In function `cgroup_move_task':
  kernel/sched/psi.c:639:13: warning: `rq' may be used uninitialized in this function [-Wmaybe-uninitialized]

Link: http://lkml.kernel.org/r/20181103183339.8669-1-olof@lixom.net


Fixes: 2ce7135adc9ad ("psi: cgroup support")
Signed-off-by: Olof Johansson <olof@lixom.net>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Change-Id: I2f21f70b6beee35d1fc77cf7dcb38f34bf96dfbd
Git-commit: 8fcb2312d1e3300e81aa871aad00d4c038cfc184
Git-repo: https://source.codeaurora.org/quic/la/kernel/msm-4.19


Signed-off-by: Patrick Daly <pdaly@codeaurora.org>

parent ae1bcb88

kernel/sched/psi.c

+22 −21

Original line number	Diff line number	Diff line
		@@ -633,12 +633,19 @@ void psi_cgroup_free(struct cgroup *cgroup)
		*/
		void cgroup_move_task(struct task_struct task, struct css_set to)
		{
		bool move_psi = !psi_disabled;
		unsigned int task_flags = 0;
		struct rq_flags rf;
		struct rq *rq;

		if (move_psi) {
		if (psi_disabled) {
		/*
		* Lame to do this here, but the scheduler cannot be locked
		* from the outside, so we move cgroups from inside sched/.
		*/
		rcu_assign_pointer(task->cgroups, to);
		return;
		}

		rq = task_rq_lock(task, &rf);

		if (task_on_rq_queued(task))
		@@ -651,21 +658,15 @@ void cgroup_move_task(struct task_struct task, struct css_set to)

		if (task_flags)
		psi_task_change(task, task_flags, 0);
		}

		/*
		* Lame to do this here, but the scheduler cannot be locked
		* from the outside, so we move cgroups from inside sched/.
		*/
		/* See comment above */
		rcu_assign_pointer(task->cgroups, to);

		if (move_psi) {
		if (task_flags)
		psi_task_change(task, 0, task_flags);

		task_rq_unlock(rq, task, &rf);
		}
		}
		#endif /* CONFIG_CGROUPS */

		int psi_show(struct seq_file m, struct psi_group group, enum psi_res res)