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rcu: disable CPU stall warnings upon panic 

The current RCU CPU stall warnings remain enabled even after a panic
occurs, which some people have found to be a bit counterproductive.
This patch therefore uses a notifier to disable stall warnings once a
panic occurs.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2010-04-15 10:12:40 -07:00
parent 55ec936ff4
commit c68de2097a
1 changed files with 24 additions and 0 deletions
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24
kernel/rcutree.c
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@ -449,6 +449,8 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
#ifdef CONFIG_RCU_CPU_STALL_DETECTOR #ifdef CONFIG_RCU_CPU_STALL_DETECTOR
int rcu_cpu_stall_panicking __read_mostly;
static void record_gp_stall_check_time(struct rcu_state *rsp) static void record_gp_stall_check_time(struct rcu_state *rsp)
{ {
rsp->gp_start = jiffies; rsp->gp_start = jiffies;
@ -526,6 +528,8 @@ static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp)
long delta; long delta;
struct rcu_node *rnp; struct rcu_node *rnp;
if (rcu_cpu_stall_panicking)
return;
delta = jiffies - rsp->jiffies_stall; delta = jiffies - rsp->jiffies_stall;
rnp = rdp->mynode; rnp = rdp->mynode;
if ((rnp->qsmask & rdp->grpmask) && delta >= 0) { if ((rnp->qsmask & rdp->grpmask) && delta >= 0) {
@ -540,6 +544,21 @@ static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp)
} }
} }
static int rcu_panic(struct notifier_block *this, unsigned long ev, void *ptr)
{
rcu_cpu_stall_panicking = 1;
return NOTIFY_DONE;
}
static struct notifier_block rcu_panic_block = {
.notifier_call = rcu_panic,
};
static void __init check_cpu_stall_init(void)
{
atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block);
}
#else /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ #else /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
static void record_gp_stall_check_time(struct rcu_state *rsp) static void record_gp_stall_check_time(struct rcu_state *rsp)
@ -550,6 +569,10 @@ static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp)
{ {
} }
static void __init check_cpu_stall_init(void)
{
}
#endif /* #else #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ #endif /* #else #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
/* /*
@ -1934,6 +1957,7 @@ void __init rcu_init(void)
cpu_notifier(rcu_cpu_notify, 0); cpu_notifier(rcu_cpu_notify, 0);
for_each_online_cpu(cpu) for_each_online_cpu(cpu)
rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)cpu); rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)cpu);
check_cpu_stall_init();
} }
#include "rcutree_plugin.h" #include "rcutree_plugin.h"