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authorFrederic Weisbecker <fweisbec@gmail.com>2009-12-16 20:21:05 +0100
committerIngo Molnar <mingo@elte.hu>2009-12-17 09:46:44 +0100
commit234da7bcdc7aaa935846534c3b726dbc79a9cdd5 (patch)
treea391afd465d6493a9f1bb274c225bab4d303aad0 /include
parent416eb39556a03d1c7e52b0791e9052ccd71db241 (diff)
sched: Teach might_sleep() about preemptible RCU
In practice, it is harmless to voluntarily sleep in a rcu_read_lock() section if we are running under preempt rcu, but it is illegal if we build a kernel running non-preemptable rcu. Currently, might_sleep() doesn't notice sleepable operations under rcu_read_lock() sections if we are running under preemptable rcu because preempt_count() is left untouched after rcu_read_lock() in this case. But we want developers who test their changes under such config to notice the "sleeping while atomic" issues. So we add rcu_read_lock_nesting to prempt_count() in might_sleep() checks. [ v2: Handle rcu-tiny ] Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> LKML-Reference: <1260991265-8451-1-git-send-regression-fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include')
-rw-r--r--include/linux/rcutiny.h5
-rw-r--r--include/linux/rcutree.h11
2 files changed, 16 insertions, 0 deletions
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index c4ba9a78721e..96cc307ed9f4 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -101,4 +101,9 @@ static inline void exit_rcu(void)
{
}
+static inline int rcu_preempt_depth(void)
+{
+ return 0;
+}
+
#endif /* __LINUX_RCUTINY_H */
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index c93eee5911b0..8044b1b94333 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -45,6 +45,12 @@ extern void __rcu_read_unlock(void);
extern void synchronize_rcu(void);
extern void exit_rcu(void);
+/*
+ * Defined as macro as it is a very low level header
+ * included from areas that don't even know about current
+ */
+#define rcu_preempt_depth() (current->rcu_read_lock_nesting)
+
#else /* #ifdef CONFIG_TREE_PREEMPT_RCU */
static inline void __rcu_read_lock(void)
@@ -63,6 +69,11 @@ static inline void exit_rcu(void)
{
}
+static inline int rcu_preempt_depth(void)
+{
+ return 0;
+}
+
#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
static inline void __rcu_read_lock_bh(void)