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authorLai Jiangshan <laijs@cn.fujitsu.com>2010-04-20 16:23:07 +0800
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2010-05-10 11:08:31 -0700
commit2b3fc35f6919344e3cf722dde8308f47235c0b70 (patch)
tree2bc2cfc9c1a032d51a3d99a10e309e100b9eea4a /kernel/lockdep.c
parentb57f95a38233a2e73b679bea4a5453a1cc2a1cc9 (diff)
rcu: optionally leave lockdep enabled after RCU lockdep splat
There is no need to disable lockdep after an RCU lockdep splat, so remove the debug_lockdeps_off() from lockdep_rcu_dereference(). To avoid repeated lockdep splats, use a static variable in the inlined rcu_dereference_check() and rcu_dereference_protected() macros so that a given instance splats only once, but so that multiple instances can be detected per boot. This is controlled by a new config variable CONFIG_PROVE_RCU_REPEATEDLY, which is disabled by default. This provides the normal lockdep behavior by default, but permits people who want to find multiple RCU-lockdep splats per boot to easily do so. Requested-by: Eric Paris <eparis@redhat.com> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Tested-by: Eric Paris <eparis@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/lockdep.c')
-rw-r--r--kernel/lockdep.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 2594e1ce41c..3a756ba8d5d 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -3801,8 +3801,11 @@ void lockdep_rcu_dereference(const char *file, const int line)
{
struct task_struct *curr = current;
+#ifndef CONFIG_PROVE_RCU_REPEATEDLY
if (!debug_locks_off())
return;
+#endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
+ /* Note: the following can be executed concurrently, so be careful. */
printk("\n===================================================\n");
printk( "[ INFO: suspicious rcu_dereference_check() usage. ]\n");
printk( "---------------------------------------------------\n");