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rcu: Add random PROVE_RCU_DELAY to grace-period initialization

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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: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
This commit is contained in:
Paul E. McKenney 2012-07-07 05:57:03 -07:00
parent 5d4b865949
commit 661a85dc0d
1 changed files with 5 additions and 0 deletions
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5
kernel/rcutree.c
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@ -52,6 +52,7 @@
#include <linux/prefetch.h> #include <linux/prefetch.h>
#include <linux/delay.h> #include <linux/delay.h>
#include <linux/stop_machine.h> #include <linux/stop_machine.h>
#include <linux/random.h>
#include "rcutree.h" #include "rcutree.h"
#include <trace/events/rcu.h> #include <trace/events/rcu.h>
@ -1087,6 +1088,10 @@ static int rcu_gp_init(struct rcu_state *rsp)
rnp->level, rnp->grplo, rnp->level, rnp->grplo,
rnp->grphi, rnp->qsmask); rnp->grphi, rnp->qsmask);
raw_spin_unlock_irq(&rnp->lock); 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(); cond_resched();
} }