Commit 2bdba316 authored by Mathieu Desnoyers's avatar Mathieu Desnoyers Committed by Ingo Molnar
Browse files

markers: fix unregister 



Impact: fix marker registers/unregister race

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.

Signed-off-by: default avatarMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 954e100d

kernel/marker.c

+7 −5
Original line number Diff line number Diff line
@@ -653,10 +653,11 @@ int marker_probe_register(const char *name, const char *format, 
		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 *name, 
		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(marker_probe_func *probe, 
		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;

CRA Git | Maintained and supported by SUSTech CRA and CCSE