Commit 0f0d1b8e authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Peter Zijlstra
Browse files

sched/ext: Remove sched_fork() hack 



Instead of solving the underlying problem of the double invocation of
__sched_fork() for idle tasks, sched-ext decided to hack around the issue
by partially clearing out the entity struct to preserve the already
enqueued node. A provided analysis and solution has been ignored for four
months.

Now that someone else has taken care of cleaning it up, remove the
disgusting hack and clear out the full structure. Remove the comment in the
structure declaration as well, as there is no requirement for @node being
the last element anymore.

Fixes: f0e1a064 ("sched_ext: Implement BPF extensible scheduler class")
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/87ldy82wkc.ffs@tglx
parent b23decf8

include/linux/sched/ext.h

+0 −1
Original line number Diff line number Diff line
@@ -199,7 +199,6 @@ struct sched_ext_entity { 
#ifdef CONFIG_EXT_GROUP_SCHED

	struct cgroup		*cgrp_moving_from;

#endif

	/* must be the last field, see init_scx_entity() */

	struct list_head	tasks_node;

};

kernel/sched/ext.c

+1 −6
Original line number Diff line number Diff line
@@ -3548,12 +3548,7 @@ static void scx_ops_exit_task(struct task_struct *p) 


void init_scx_entity(struct sched_ext_entity *scx)

{

	/*

	 * init_idle() calls this function again after fork sequence is

	 * complete. Don't touch ->tasks_node as it's already linked.

	 */

	memset(scx, 0, offsetof(struct sched_ext_entity, tasks_node));



	memset(scx, 0, sizeof(*scx));

	INIT_LIST_HEAD(&scx->dsq_list.node);

	RB_CLEAR_NODE(&scx->dsq_priq);

	scx->sticky_cpu = -1;