[RFC][PATCH 18/26] srcu: revert2

Peter Zijlstra
2012-03-16T14:55:31Z

[-- Attachment #1: srcu-revert-2.patch --]
[-- Type: text/plain, Size: 3250 bytes --]

rcu: Add lockdep-RCU checks for simple self-deadlock

It is illegal to have a grace period within a same-flavor RCU read-side
critical section, so this commit adds lockdep-RCU checks to splat when
such abuse is encountered. This commit does not detect more elaborate
RCU deadlock situations. These situations might be a job for lockdep
enhancements.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
kernel/rcutiny.c | 4 ----
kernel/rcutiny_plugin.h | 5 -----
kernel/rcutree.c | 8 --------
kernel/rcutree_plugin.h | 4 ----
kernel/srcu.c | 6 ------
5 files changed, 27 deletions(-)

--- a/kernel/rcutiny.c
+++ b/kernel/rcutiny.c
@@ -329,10 +329,6 @@ static void rcu_process_callbacks(struct
*/
void synchronize_sched(void)
{
- rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map) &&
- !lock_is_held(&rcu_lock_map) &&
- !lock_is_held(&rcu_sched_lock_map),
- "Illegal synchronize_sched() in RCU read-side critical section");
cond_resched();
}
EXPORT_SYMBOL_GPL(synchronize_sched);
--- a/kernel/rcutiny_plugin.h
+++ b/kernel/rcutiny_plugin.h
@@ -735,11 +735,6 @@ EXPORT_SYMBOL_GPL(call_rcu);
*/
void synchronize_rcu(void)
{
- rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map) &&
- !lock_is_held(&rcu_lock_map) &&
- !lock_is_held(&rcu_sched_lock_map),
- "Illegal synchronize_rcu() in RCU read-side critical section");
-
#ifdef CONFIG_DEBUG_LOCK_ALLOC
if (!rcu_scheduler_active)
return;
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -1919,10 +1919,6 @@ EXPORT_SYMBOL_GPL(call_rcu_bh);
*/
void synchronize_sched(void)
{
- rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map) &&
- !lock_is_held(&rcu_lock_map) &&
- !lock_is_held(&rcu_sched_lock_map),
- "Illegal synchronize_sched() in RCU-sched read-side critical section");
if (rcu_blocking_is_gp())
return;
wait_rcu_gp(call_rcu_sched);
@@ -1940,10 +1936,6 @@ EXPORT_SYMBOL_GPL(synchronize_sched);
*/
void synchronize_rcu_bh(void)
{
- rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map) &&
- !lock_is_held(&rcu_lock_map) &&
- !lock_is_held(&rcu_sched_lock_map),
- "Illegal synchronize_rcu_bh() in RCU-bh read-side critical section");
if (rcu_blocking_is_gp())
return;
wait_rcu_gp(call_rcu_bh);
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -731,10 +731,6 @@ EXPORT_SYMBOL_GPL(kfree_call_rcu);
*/
void synchronize_rcu(void)
{
- rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map) &&
- !lock_is_held(&rcu_lock_map) &&
- !lock_is_held(&rcu_sched_lock_map),
- "Illegal synchronize_rcu() in RCU read-side critical section");
if (!rcu_scheduler_active)
return;
wait_rcu_gp(call_rcu);
--- a/kernel/srcu.c
+++ b/kernel/srcu.c
@@ -172,12 +172,6 @@ static void __synchronize_srcu(struct sr
{
int idx;

- rcu_lockdep_assert(!lock_is_held(&sp->dep_map) &&
- !lock_is_held(&rcu_bh_lock_map) &&
- !lock_is_held(&rcu_lock_map) &&
- !lock_is_held(&rcu_sched_lock_map),
- "Illegal synchronize_srcu() in same-type SRCU (or RCU) read-side critical section");
-
idx = sp->completed;
mutex_lock(&sp->mutex);