Commit 85dd3f61 authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

sched: Inherit task cookie on fork() 



Note that sched_core_fork() is called from under tasklist_lock, and
not from sched_fork() earlier. This avoids a few races later.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: default avatarDon Hiatt <dhiatt@digitalocean.com>
Tested-by: default avatarHongyu Ning <hongyu.ning@linux.intel.com>
Tested-by: default avatarVincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20210422123308.980003687@infradead.org
parent 6e33cad0

include/linux/sched.h

+2 −0
Original line number Diff line number Diff line
@@ -2181,8 +2181,10 @@ const struct cpumask *sched_trace_rd_span(struct root_domain *rd); 


#ifdef CONFIG_SCHED_CORE

extern void sched_core_free(struct task_struct *tsk);

extern void sched_core_fork(struct task_struct *p);

#else

static inline void sched_core_free(struct task_struct *tsk) { }

static inline void sched_core_fork(struct task_struct *p) { }

#endif



#endif

kernel/fork.c

+3 −0
Original line number Diff line number Diff line
@@ -2251,6 +2251,8 @@ static __latent_entropy struct task_struct *copy_process( 


	klp_copy_process(p);



	sched_core_fork(p);



	spin_lock(&current->sighand->siglock);



	/*
@@ -2338,6 +2340,7 @@ static __latent_entropy struct task_struct *copy_process( 
	return p;



bad_fork_cancel_cgroup:

	sched_core_free(p);

	spin_unlock(&current->sighand->siglock);

	write_unlock_irq(&tasklist_lock);

	cgroup_cancel_fork(p, args);

kernel/sched/core_sched.c

+6 −0
Original line number Diff line number Diff line
@@ -103,6 +103,12 @@ static unsigned long sched_core_clone_cookie(struct task_struct *p) 
	return cookie;

}



void sched_core_fork(struct task_struct *p)

{

	RB_CLEAR_NODE(&p->core_node);

	p->core_cookie = sched_core_clone_cookie(current);

}



void sched_core_free(struct task_struct *p)

{

	sched_core_put_cookie(p->core_cookie);