Messages in this thread | | | From | David Laight <> | Subject | RE: [PATCH] sched/fair: remove the spin_lock operations | Date | Fri, 30 Oct 2020 22:16:29 +0000 |
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From: Benjamin Segall > Sent: 30 October 2020 18:48 > > Hui Su <sh_def@163.com> writes: > > > Since 'ab93a4bc955b ("sched/fair: Remove > > distribute_running fromCFS bandwidth")',there is > > nothing to protect between raw_spin_lock_irqsave/store() > > in do_sched_cfs_slack_timer(). > > > > So remove it. > > Reviewed-by: Ben Segall <bsegall@google.com> > > (I might nitpick the subject to be clear that it should be trivial > because the lock area is empty, or call them dead or something, but it's > not all that important)
I don't know about this case, but a lock+unlock can be used to ensure that nothing else holds the lock when acquiring the lock requires another lock be held.
So if the normal sequence is: lock(table) # lookup item lock(item) unlock(table) .... unlock(item)
Then it can make sense to do: lock(table) lock(item) unlock(item) .... unlock(table)
although that ought to deserve a comment.
avid
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