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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2013-04-23 11:31:50 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2013-08-18 17:39:45 -0700
commit15100df81fcc3109862f7c03266c0abff4262564 (patch)
tree7f5e414bd3d332d653c7cc6b499cbddd2c9f5eba
parentd1d74d14e98a6be740a6f12456c7d9ad47be9c9c (diff)
rcu: Simplify debug-objects fixups
The current debug-objects fixups are complex and heavyweight, and the fixups are not complete: Even with the fixups, RCU's callback lists can still be corrupted. This commit therefore strips the fixups down to their minimal form, eliminating two of the three. It would be even better if (for example) call_rcu() simply leaked any problematic callbacks, but for that to happen, the debug-objects system would need to inform its caller of suspicious situations. This is the subject of a later commit in this series. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Sedat Dilek <sedat.dilek@gmail.com> Cc: Davidlohr Bueso <davidlohr.bueso@hp.com> Cc: Rik van Riel <riel@surriel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
-rw-r--r--kernel/rcupdate.c100
1 files changed, 0 insertions, 100 deletions
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
index 14994d4e1a54..33eb4620aa17 100644
--- a/kernel/rcupdate.c
+++ b/kernel/rcupdate.c
@@ -212,43 +212,6 @@ static inline void debug_rcu_head_free(struct rcu_head *head)
}
/*
- * fixup_init is called when:
- * - an active object is initialized
- */
-static int rcuhead_fixup_init(void *addr, enum debug_obj_state state)
-{
- struct rcu_head *head = addr;
-
- switch (state) {
- case ODEBUG_STATE_ACTIVE:
- /*
- * Ensure that queued callbacks are all executed.
- * If we detect that we are nested in a RCU read-side critical
- * section, we should simply fail, otherwise we would deadlock.
- * In !PREEMPT configurations, there is no way to tell if we are
- * in a RCU read-side critical section or not, so we never
- * attempt any fixup and just print a warning.
- */
-#ifndef CONFIG_PREEMPT
- WARN_ON_ONCE(1);
- return 0;
-#endif
- if (rcu_preempt_depth() != 0 || preempt_count() != 0 ||
- irqs_disabled()) {
- WARN_ON_ONCE(1);
- return 0;
- }
- rcu_barrier();
- rcu_barrier_sched();
- rcu_barrier_bh();
- debug_object_init(head, &rcuhead_debug_descr);
- return 1;
- default:
- return 0;
- }
-}
-
-/*
* fixup_activate is called when:
* - an active object is activated
* - an unknown object is activated (might be a statically initialized object)
@@ -268,69 +231,8 @@ static int rcuhead_fixup_activate(void *addr, enum debug_obj_state state)
debug_object_init(head, &rcuhead_debug_descr);
debug_object_activate(head, &rcuhead_debug_descr);
return 0;
-
- case ODEBUG_STATE_ACTIVE:
- /*
- * Ensure that queued callbacks are all executed.
- * If we detect that we are nested in a RCU read-side critical
- * section, we should simply fail, otherwise we would deadlock.
- * In !PREEMPT configurations, there is no way to tell if we are
- * in a RCU read-side critical section or not, so we never
- * attempt any fixup and just print a warning.
- */
-#ifndef CONFIG_PREEMPT
- WARN_ON_ONCE(1);
- return 0;
-#endif
- if (rcu_preempt_depth() != 0 || preempt_count() != 0 ||
- irqs_disabled()) {
- WARN_ON_ONCE(1);
- return 0;
- }
- rcu_barrier();
- rcu_barrier_sched();
- rcu_barrier_bh();
- debug_object_activate(head, &rcuhead_debug_descr);
- return 1;
default:
- return 0;
- }
-}
-
-/*
- * fixup_free is called when:
- * - an active object is freed
- */
-static int rcuhead_fixup_free(void *addr, enum debug_obj_state state)
-{
- struct rcu_head *head = addr;
-
- switch (state) {
- case ODEBUG_STATE_ACTIVE:
- /*
- * Ensure that queued callbacks are all executed.
- * If we detect that we are nested in a RCU read-side critical
- * section, we should simply fail, otherwise we would deadlock.
- * In !PREEMPT configurations, there is no way to tell if we are
- * in a RCU read-side critical section or not, so we never
- * attempt any fixup and just print a warning.
- */
-#ifndef CONFIG_PREEMPT
- WARN_ON_ONCE(1);
- return 0;
-#endif
- if (rcu_preempt_depth() != 0 || preempt_count() != 0 ||
- irqs_disabled()) {
- WARN_ON_ONCE(1);
- return 0;
- }
- rcu_barrier();
- rcu_barrier_sched();
- rcu_barrier_bh();
- debug_object_free(head, &rcuhead_debug_descr);
return 1;
- default:
- return 0;
}
}
@@ -369,9 +271,7 @@ EXPORT_SYMBOL_GPL(destroy_rcu_head_on_stack);
struct debug_obj_descr rcuhead_debug_descr = {
.name = "rcu_head",
- .fixup_init = rcuhead_fixup_init,
.fixup_activate = rcuhead_fixup_activate,
- .fixup_free = rcuhead_fixup_free,
};
EXPORT_SYMBOL_GPL(rcuhead_debug_descr);
#endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */