Commit 204ab514 authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Frederic Weisbecker
Browse files

refscale: Do not disable interrupts for tests involving local_bh_enable() 



Some kernel configurations prohibit invoking local_bh_enable() while
interrupts are disabled.  However, refscale disables interrupts to reduce
OS noise during the tests, which results in splats.  This commit therefore
adds an ->enable_irqs flag to the ref_scale_ops structure, and refrains
from disabling interrupts when that flag is set.  This flag is set for
the "bh" and "incpercpubh" scale_type module-parameter values.

Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Signed-off-by: default avatarFrederic Weisbecker <frederic@kernel.org>
parent 448b66a7

kernel/rcu/refscale.c

+10 −4
Original line number Diff line number Diff line
@@ -136,6 +136,7 @@ struct ref_scale_ops { 
	void (*cleanup)(void);

	void (*readsection)(const int nloops);

	void (*delaysection)(const int nloops, const int udl, const int ndl);

	bool enable_irqs;

	const char *name;

};
@@ -488,6 +489,7 @@ static const struct ref_scale_ops incpercpubh_ops = { 
	.init		= rcu_sync_scale_init,

	.readsection	= ref_incpercpubh_section,

	.delaysection	= ref_incpercpubh_delay_section,

	.enable_irqs	= true,

	.name		= "incpercpubh"

};
@@ -865,6 +867,7 @@ static void ref_bh_delay_section(const int nloops, const int udl, const int ndl) 
static const struct ref_scale_ops bh_ops = {

	.readsection	= ref_bh_section,

	.delaysection	= ref_bh_delay_section,

	.enable_irqs	= true,

	.name		= "bh"

};
@@ -1227,14 +1230,17 @@ ref_scale_reader(void *arg) 
	if (!atomic_dec_return(&n_warmedup))

		while (atomic_read_acquire(&n_warmedup))

			rcu_scale_one_reader();

	// Also keep interrupts disabled.  This also has the effect

	// of preventing entries into slow path for rcu_read_unlock().

	// Also keep interrupts disabled when it is safe to do so, which

	// it is not for local_bh_enable().  This also has the effect of

	// preventing entries into slow path for rcu_read_unlock().

	if (!cur_ops->enable_irqs)

		local_irq_save(flags);

	start = ktime_get_mono_fast_ns();



	rcu_scale_one_reader();



	duration = ktime_get_mono_fast_ns() - start;

	if (!cur_ops->enable_irqs)

		local_irq_restore(flags);



	rt->last_duration_ns = WARN_ON_ONCE(duration < 0) ? 0 : duration;