Messages in this thread Patch in this message | | | Date | Tue, 6 Oct 2009 11:19:14 -0400 | From | Mathieu Desnoyers <> | Subject | Re: [patch 1/4] kernel call_rcu usage: initialize rcu_head structures (v2) |
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Initialize rcu_head structures before passing them to call_rcu() to eliminate false positives in DEBUG_RCU_HEAD.
Update: init at structure allocation time rather than just before calling call_rcu(). Ensures we do not void the debug race test.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> CC: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> CC: mingo@elte.hu CC: akpm@linux-foundation.org --- kernel/fork.c | 1 + kernel/pid.c | 1 + kernel/rcupdate.c | 1 + 3 files changed, 3 insertions(+)
Index: linux-2.6-lttng/kernel/rcupdate.c =================================================================== --- linux-2.6-lttng.orig/kernel/rcupdate.c 2009-10-06 10:34:25.000000000 -0400 +++ linux-2.6-lttng/kernel/rcupdate.c 2009-10-06 11:17:16.000000000 -0400 @@ -90,6 +90,7 @@ void synchronize_rcu(void) if (rcu_blocking_is_gp()) return; + INIT_RCU_HEAD(&rcu.head); init_completion(&rcu.completion); /* Will wake me after RCU finished. */ call_rcu(&rcu.head, wakeme_after_rcu); Index: linux-2.6-lttng/kernel/pid.c =================================================================== --- linux-2.6-lttng.orig/kernel/pid.c 2009-10-06 10:34:25.000000000 -0400 +++ linux-2.6-lttng/kernel/pid.c 2009-10-06 11:12:46.000000000 -0400 @@ -264,6 +264,7 @@ struct pid *alloc_pid(struct pid_namespa get_pid_ns(ns); pid->level = ns->level; + INIT_RCU_HEAD(&pid->rcu); atomic_set(&pid->count, 1); for (type = 0; type < PIDTYPE_MAX; ++type) INIT_HLIST_HEAD(&pid->tasks[type]); Index: linux-2.6-lttng/kernel/fork.c =================================================================== --- linux-2.6-lttng.orig/kernel/fork.c 2009-10-06 11:11:10.000000000 -0400 +++ linux-2.6-lttng/kernel/fork.c 2009-10-06 11:11:54.000000000 -0400 @@ -1012,6 +1012,7 @@ static struct task_struct *copy_process( p->rcu_read_lock_nesting = 0; p->rcu_flipctr_idx = 0; #endif /* #ifdef CONFIG_PREEMPT_RCU */ + INIT_RCU_HEAD(&p->rcu); p->vfork_done = NULL; spin_lock_init(&p->alloc_lock); -- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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