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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2010-02-22 20:04:45 -0500
committerIngo Molnar <mingo@elte.hu>2010-02-25 03:40:59 -0500
commit632ee200130899252508c478ad0e808222573fbc (patch)
treee3f44ca9daf2a2da2186419f703bc9cec8faa058 /kernel/rcupdate.c
parent996de8c6fe95c5a9fc524241cc8f142ef0605d3d (diff)
rcu: Introduce lockdep-based checking to RCU read-side primitives
Inspection is proving insufficient to catch all RCU misuses, which is understandable given that rcu_dereference() might be protected by any of four different flavors of RCU (RCU, RCU-bh, RCU-sched, and SRCU), and might also/instead be protected by any of a number of locking primitives. It is therefore time to enlist the aid of lockdep. This set of patches is inspired by earlier work by Peter Zijlstra and Thomas Gleixner, and takes the following approach: o Set up separate lockdep classes for RCU, RCU-bh, and RCU-sched. o Set up separate lockdep classes for each instance of SRCU. o Create primitives that check for being in an RCU read-side critical section. These return exact answers if lockdep is fully enabled, but if unsure, report being in an RCU read-side critical section. (We want to avoid false positives!) The primitives are: For RCU: rcu_read_lock_held(void) For RCU-bh: rcu_read_lock_bh_held(void) For RCU-sched: rcu_read_lock_sched_held(void) For SRCU: srcu_read_lock_held(struct srcu_struct *sp) o Add rcu_dereference_check(), which takes a second argument in which one places a boolean expression based on the above primitives and/or lockdep_is_held(). o A new kernel configuration parameter, CONFIG_PROVE_RCU, enables rcu_dereference_check(). This depends on CONFIG_PROVE_LOCKING, and should be quite helpful during the transition period while CONFIG_PROVE_RCU-unaware patches are in flight. The existing rcu_dereference() primitive does no checking, but upcoming patches will change that. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <1266887105-1528-1-git-send-email-paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/rcupdate.c')
-rw-r--r--kernel/rcupdate.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
index 9b7fd4723878..033cb55c26df 100644
--- a/kernel/rcupdate.c
+++ b/kernel/rcupdate.c
@@ -50,6 +50,16 @@ static struct lock_class_key rcu_lock_key;
50struct lockdep_map rcu_lock_map = 50struct lockdep_map rcu_lock_map =
51 STATIC_LOCKDEP_MAP_INIT("rcu_read_lock", &rcu_lock_key); 51 STATIC_LOCKDEP_MAP_INIT("rcu_read_lock", &rcu_lock_key);
52EXPORT_SYMBOL_GPL(rcu_lock_map); 52EXPORT_SYMBOL_GPL(rcu_lock_map);
53
54static struct lock_class_key rcu_bh_lock_key;
55struct lockdep_map rcu_bh_lock_map =
56 STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_bh", &rcu_bh_lock_key);
57EXPORT_SYMBOL_GPL(rcu_bh_lock_map);
58
59static struct lock_class_key rcu_sched_lock_key;
60struct lockdep_map rcu_sched_lock_map =
61 STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_sched", &rcu_sched_lock_key);
62EXPORT_SYMBOL_GPL(rcu_sched_lock_map);
53#endif 63#endif
54 64
55/* 65/*