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Commit 661a85dc authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu: Add random PROVE_RCU_DELAY to grace-period initialization 



Preemption greatly raised the probability of certain types of race
conditions, so this commit adds an anti-heisenbug to greatly increase
the collision cross section, also known as the probability of occurrence.

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: default avatarJosh Triplett <josh@joshtriplett.org>
parent 5d4b8659

kernel/rcutree.c

+5 −0
Original line number Diff line number Diff line
@@ -52,6 +52,7 @@ 
#include <linux/prefetch.h>

#include <linux/delay.h>

#include <linux/stop_machine.h>

#include <linux/random.h>



#include "rcutree.h"

#include <trace/events/rcu.h>
@@ -1087,6 +1088,10 @@ static int rcu_gp_init(struct rcu_state *rsp) 
					    rnp->level, rnp->grplo,

					    rnp->grphi, rnp->qsmask);

		raw_spin_unlock_irq(&rnp->lock);

#ifdef CONFIG_PROVE_RCU_DELAY

		if ((random32() % (rcu_num_nodes * 8)) == 0)

			schedule_timeout_uninterruptible(2);

#endif /* #ifdef CONFIG_PROVE_RCU_DELAY */

		cond_resched();

	}