sched/fair: Remove superfluous rcu_read_lock() in the wakeup path

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select_task_rq_fair() is always called with p->pi_lock held and IRQs
disabled which makes it equivalent of an RCU read-side.

Since commit 71fedc41c2 ("sched/fair: Switch to
rcu_dereference_all()") switched to using rcu_dereference_all() in the
wakeup path, drop the explicit rcu_read_{lock,unlock}() in the fair
task's wakeup path.

Future plans to reuse select_task_rq_fair() /
find_energy_efficient_cpu() in the fair class' balance callback will do
so with IRQs disabled and will comply with the requirements of
rcu_dereference_all() which makes this safe keeping in mind future
development plans too.

Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://patch.msgid.link/20260312044434.1974-8-kprateek.nayak@amd.com

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K Prateek Nayak 2026-03-12 04:44:32 +00:00 • committed by Peter Zijlstra

parent 8ca12326f5

commit fa6874dfee

1 changed files with 12 additions and 21 deletions

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kernel/sched/fair.c

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