From b3fbab0571eb09746cc0283648165ec00efc8eb2 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 24 May 2011 08:31:09 -0700 Subject: rcu: Restore checks for blocking in RCU read-side critical sections Long ago, using TREE_RCU with PREEMPT would result in "scheduling while atomic" diagnostics if you blocked in an RCU read-side critical section. However, PREEMPT now implies TREE_PREEMPT_RCU, which defeats this diagnostic. This commit therefore adds a replacement diagnostic based on PROVE_RCU. Because rcu_lockdep_assert() and lockdep_rcu_dereference() are now being used for things that have nothing to do with rcu_dereference(), rename lockdep_rcu_dereference() to lockdep_rcu_suspicious() and add a third argument that is a string indicating what is suspicious. This third argument is passed in from a new third argument to rcu_lockdep_assert(). Update all calls to rcu_lockdep_assert() to add an informative third argument. Also, add a pair of rcu_lockdep_assert() calls from within rcu_note_context_switch(), one complaining if a context switch occurs in an RCU-bh read-side critical section and another complaining if a context switch occurs in an RCU-sched read-side critical section. These are present only if the PROVE_RCU kernel parameter is enabled. Finally, fix some checkpatch whitespace complaints in lockdep.c. Again, you must enable PROVE_RCU to see these new diagnostics. But you are enabling PROVE_RCU to check out new RCU uses in any case, aren't you? Signed-off-by: Paul E. McKenney --- kernel/sched.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'kernel/sched.c') diff --git a/kernel/sched.c b/kernel/sched.c index ec5f472bc5b9..e24cebe0e6cb 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -4237,6 +4237,7 @@ static inline void schedule_debug(struct task_struct *prev) */ if (unlikely(in_atomic_preempt_off() && !prev->exit_state)) __schedule_bug(prev); + rcu_sleep_check(); profile_hit(SCHED_PROFILING, __builtin_return_address(0)); @@ -8230,6 +8231,7 @@ void __might_sleep(const char *file, int line, int preempt_offset) { static unsigned long prev_jiffy; /* ratelimiting */ + rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */ if ((preempt_count_equals(preempt_offset) && !irqs_disabled()) || system_state != SYSTEM_RUNNING || oops_in_progress) return; -- cgit v1.2.3