Messages in this thread Patch in this message | | | Date | Mon, 31 Mar 2008 09:16:09 -0400 | From | Mathieu Desnoyers <> | Subject | [PATCH for 2.6.25] Markers - use synchronize_sched() |
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Use synchronize_sched before calling call_rcu in CONFIG_PREEMPT_RCU until we have call_rcu_sched and rcu_barrier_sched in mainline. It will slow down the marker operations in CONFIG_PREEMPT_RCU, but it fixes the current race against the preempt_disable/enable() protected code paths.
Paul, is this ok ? It would be good to get this in for 2.6.25 final.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> CC: Paul E. McKenney <paulmck@linux.vnet.ibm.com> --- kernel/marker.c | 9 +++++++++ 1 file changed, 9 insertions(+)
Index: linux-2.6-lttng/kernel/marker.c =================================================================== --- linux-2.6-lttng.orig/kernel/marker.c 2008-03-31 08:22:24.000000000 -0400 +++ linux-2.6-lttng/kernel/marker.c 2008-03-31 08:43:30.000000000 -0400 @@ -671,6 +671,9 @@ int marker_probe_register(const char *na entry->rcu_pending = 1; /* write rcu_pending before calling the RCU callback */ smp_wmb(); +#ifdef CONFIG_PREEMPT_RCU + synchronize_sched(); /* Until we have the call_rcu_sched() */ +#endif call_rcu(&entry->rcu, free_old_closure); end: mutex_unlock(&markers_mutex); @@ -714,6 +717,9 @@ int marker_probe_unregister(const char * entry->rcu_pending = 1; /* write rcu_pending before calling the RCU callback */ smp_wmb(); +#ifdef CONFIG_PREEMPT_RCU + synchronize_sched(); /* Until we have the call_rcu_sched() */ +#endif call_rcu(&entry->rcu, free_old_closure); remove_marker(name); /* Ignore busy error message */ ret = 0; @@ -792,6 +798,9 @@ int marker_probe_unregister_private_data entry->rcu_pending = 1; /* write rcu_pending before calling the RCU callback */ smp_wmb(); +#ifdef CONFIG_PREEMPT_RCU + synchronize_sched(); /* Until we have the call_rcu_sched() */ +#endif call_rcu(&entry->rcu, free_old_closure); remove_marker(entry->name); /* Ignore busy error message */ end: -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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