Messages in this thread Patch in this message | | | Date | Fri, 14 Nov 2008 17:47:35 -0500 | From | Mathieu Desnoyers <> | Subject | [patch 02/16] Marker fix unregister |
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get_marker() can return a NULL entry because the mutex is released in the middle of those functions. Make sure we check to see if it has been concurrently removed.
Impact: Bugfix.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> CC: Lai Jiangshan <laijs@cn.fujitsu.com> --- kernel/marker.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-)
Index: linux.trees.git/kernel/marker.c =================================================================== --- linux.trees.git.orig/kernel/marker.c 2008-11-14 17:38:39.000000000 -0500 +++ linux.trees.git/kernel/marker.c 2008-11-14 17:38:43.000000000 -0500 @@ -653,10 +653,11 @@ int marker_probe_register(const char *na goto end; } mutex_unlock(&markers_mutex); - marker_update_probes(); /* may update entry */ + marker_update_probes(); mutex_lock(&markers_mutex); entry = get_marker(name); - WARN_ON(!entry); + if (!entry) + goto end; if (entry->rcu_pending) rcu_barrier_sched(); entry->oldptr = old; @@ -697,7 +698,7 @@ int marker_probe_unregister(const char * rcu_barrier_sched(); old = marker_entry_remove_probe(entry, probe, probe_private); mutex_unlock(&markers_mutex); - marker_update_probes(); /* may update entry */ + marker_update_probes(); mutex_lock(&markers_mutex); entry = get_marker(name); if (!entry) @@ -778,10 +779,11 @@ int marker_probe_unregister_private_data rcu_barrier_sched(); old = marker_entry_remove_probe(entry, NULL, probe_private); mutex_unlock(&markers_mutex); - marker_update_probes(); /* may update entry */ + marker_update_probes(); mutex_lock(&markers_mutex); entry = get_marker_from_private_data(probe, probe_private); - WARN_ON(!entry); + if (!entry) + goto end; if (entry->rcu_pending) rcu_barrier_sched(); entry->oldptr = old; -- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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