linux-kernel - Re: [PATCH 1/2] sched: Add schedule_(raw_)spin_unlock and schedule_(raw_)spin_unlock

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Date:	Mon, 24 Jun 2013 14:54:43 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Kirill Tkhai <tkhai@...dex.ru>
cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH 1/2] sched: Add schedule_(raw_)spin_unlock and
 schedule_(raw_)spin_unlock_irq

On Tue, 18 Jun 2013, Kirill Tkhai wrote:
> +/*
> + * schedule_raw_spin_unlock() -- should be used instead of pattern:
> + *
> + *     raw_spin_unlock(lock);
> + *     schedule();
> + *
> + * It's the same, but prevents preempt_schedule() call during the unlocking.
> + */
> +static inline void schedule_raw_spin_unlock(raw_spinlock_t *lock)

This should be raw_spin_unlock_and_schedule().

schedule_raw_spin_unlock() sounds like we schedule a raw_spin_unlock()
for some point in the future.

> +{
> +	_raw_spin_unlock_no_resched(lock);

No, please do not expose such an interface. Instead of that implement
it as:

raw_spin_unlock_and_schedule()
{
	spin_release(&lock->dep_map, 1, _RET_IP_);
	do_raw_spin_unlock(lock);
	preempt_enable_no_resched();
	schedule();  
}

And this goes into the spinlock header and not into sched.h.

Thanks,

	tglx
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