Commit-ID: 24ef659a857c3cba40b64ea51ea4fce8d2fb7bbc
Gitweb: http://git.kernel.org/tip/24ef659a857c3cba40b64ea51ea4fce8d2fb7bbc
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Mon, 28 Oct 2013 09:22:24 -0700
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Mon, 9 Dec 2013 15:12:39 -0800
rcu: Provide better diagnostics for blocking in RCU callback functions
Currently blocking in an RCU callback function will result in
"scheduling while atomic", which could be triggered for any number
of reasons. To aid debugging, this patch introduces a rcu_callback_map
that is used to tie the inappropriate voluntary context switch back
to the fact that the function is being invoked from within a callback.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
include/linux/rcupdate.h | 1 +
kernel/rcu/rcu.h | 3 +++
kernel/rcu/update.c | 5 +++++
3 files changed, 9 insertions(+)
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 39cbb88..a94a580 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -325,6 +325,7 @@ static inline void rcu_lock_release(struct lockdep_map *map)
extern struct lockdep_map rcu_lock_map;
extern struct lockdep_map rcu_bh_lock_map;
extern struct lockdep_map rcu_sched_lock_map;
+extern struct lockdep_map rcu_callback_map;
extern int debug_lockdep_rcu_enabled(void);
/**
diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
index 7859a0a..a8f981a 100644
--- a/kernel/rcu/rcu.h
+++ b/kernel/rcu/rcu.h
@@ -102,13 +102,16 @@ static inline bool __rcu_reclaim(const char *rn, struct rcu_head *head)
{
unsigned long offset = (unsigned long)head->func;
+ rcu_lock_acquire(&rcu_callback_map);
if (__is_kfree_rcu_offset(offset)) {
RCU_TRACE(trace_rcu_invoke_kfree_callback(rn, head, offset));
kfree((void *)head - offset);
+ rcu_lock_release(&rcu_callback_map);
return 1;
} else {
RCU_TRACE(trace_rcu_invoke_callback(rn, head));
head->func(head);
+ rcu_lock_release(&rcu_callback_map);
return 0;
}
}
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 6cb3dff..802365c 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -128,6 +128,11 @@ struct lockdep_map rcu_sched_lock_map =
STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_sched", &rcu_sched_lock_key);
EXPORT_SYMBOL_GPL(rcu_sched_lock_map);
+static struct lock_class_key rcu_callback_key;
+struct lockdep_map rcu_callback_map =
+ STATIC_LOCKDEP_MAP_INIT("rcu_callback", &rcu_callback_key);
+EXPORT_SYMBOL_GPL(rcu_callback_map);
+
int notrace debug_lockdep_rcu_enabled(void)
{
return rcu_scheduler_active && debug_locks &&
--
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