Upon module load, we must take the markers mutex. It implies that the marker
mutex must be nested inside the module mutex.
It implies changing the nesting order : now the marker mutex nests inside the
module mutex. Make the necessary changes to reverse the order in which the
mutexes are taken.
Includes some cleanup from Dave Hansen <[email protected]>.
Signed-off-by: Mathieu Desnoyers <[email protected]>
---
kernel/marker.c | 41 +++++++++++++++++------------------------
1 file changed, 17 insertions(+), 24 deletions(-)
Index: linux-2.6-lttng/kernel/marker.c
===================================================================
--- linux-2.6-lttng.orig/kernel/marker.c 2007-11-13 10:27:22.000000000 -0500
+++ linux-2.6-lttng/kernel/marker.c 2007-11-13 13:34:19.000000000 -0500
@@ -28,7 +28,7 @@ extern struct marker __start___markers[]
extern struct marker __stop___markers[];
/*
- * module_mutex nests inside markers_mutex. Markers mutex protects the builtin
+ * markers_mutex nests inside module_mutex. Markers mutex protects the builtin
* and module markers, the hash table and deferred_sync.
*/
static DEFINE_MUTEX(markers_mutex);
@@ -257,7 +257,6 @@ static void disable_marker(struct marker
* @refcount: number of references left to the given probe_module (out)
*
* Updates the probe callback corresponding to a range of markers.
- * Must be called with markers_mutex held.
*/
void marker_update_probe_range(struct marker *begin,
struct marker *end, struct module *probe_module,
@@ -266,6 +265,7 @@ void marker_update_probe_range(struct ma
struct marker *iter;
struct marker_entry *mark_entry;
+ mutex_lock(&markers_mutex);
for (iter = begin; iter < end; iter++) {
mark_entry = get_marker(iter->name);
if (mark_entry && mark_entry->refcount) {
@@ -281,6 +281,7 @@ void marker_update_probe_range(struct ma
disable_marker(iter);
}
}
+ mutex_unlock(&markers_mutex);
}
/*
@@ -293,7 +294,6 @@ static void marker_update_probes(struct
{
int refcount = 0;
- mutex_lock(&markers_mutex);
/* Core kernel markers */
marker_update_probe_range(__start___markers,
__stop___markers, probe_module, &refcount);
@@ -303,7 +303,6 @@ static void marker_update_probes(struct
synchronize_sched();
deferred_sync = 0;
}
- mutex_unlock(&markers_mutex);
}
/**
@@ -320,7 +319,7 @@ int marker_probe_register(const char *na
marker_probe_func *probe, void *private)
{
struct marker_entry *entry;
- int ret = 0, need_update = 0;
+ int ret = 0;
mutex_lock(&markers_mutex);
entry = get_marker(name);
@@ -335,11 +334,11 @@ int marker_probe_register(const char *na
ret = add_marker(name, format, probe, private);
if (ret)
goto end;
- need_update = 1;
+ mutex_unlock(&markers_mutex);
+ marker_update_probes(NULL);
+ return ret;
end:
mutex_unlock(&markers_mutex);
- if (need_update)
- marker_update_probes(NULL);
return ret;
}
EXPORT_SYMBOL_GPL(marker_probe_register);
@@ -355,7 +354,6 @@ void *marker_probe_unregister(const char
struct module *probe_module;
struct marker_entry *entry;
void *private;
- int need_update = 0;
mutex_lock(&markers_mutex);
entry = get_marker(name);
@@ -368,11 +366,11 @@ void *marker_probe_unregister(const char
probe_module = __module_text_address((unsigned long)entry->probe);
private = remove_marker(name);
deferred_sync = 1;
- need_update = 1;
+ mutex_unlock(&markers_mutex);
+ marker_update_probes(probe_module);
+ return private;
end:
mutex_unlock(&markers_mutex);
- if (need_update)
- marker_update_probes(probe_module);
return private;
}
EXPORT_SYMBOL_GPL(marker_probe_unregister);
@@ -392,7 +390,6 @@ void *marker_probe_unregister_private_da
struct marker_entry *entry;
int found = 0;
unsigned int i;
- int need_update = 0;
mutex_lock(&markers_mutex);
for (i = 0; i < MARKER_TABLE_SIZE; i++) {
@@ -414,11 +411,11 @@ iter_end:
probe_module = __module_text_address((unsigned long)entry->probe);
private = remove_marker(entry->name);
deferred_sync = 1;
- need_update = 1;
+ mutex_unlock(&markers_mutex);
+ marker_update_probes(probe_module);
+ return private;
end:
mutex_unlock(&markers_mutex);
- if (need_update)
- marker_update_probes(probe_module);
return private;
}
EXPORT_SYMBOL_GPL(marker_probe_unregister_private_data);
@@ -434,7 +431,7 @@ EXPORT_SYMBOL_GPL(marker_probe_unregiste
int marker_arm(const char *name)
{
struct marker_entry *entry;
- int ret = 0, need_update = 0;
+ int ret = 0;
mutex_lock(&markers_mutex);
entry = get_marker(name);
@@ -447,11 +444,9 @@ int marker_arm(const char *name)
*/
if (entry->refcount++)
goto end;
- need_update = 1;
end:
mutex_unlock(&markers_mutex);
- if (need_update)
- marker_update_probes(NULL);
+ marker_update_probes(NULL);
return ret;
}
EXPORT_SYMBOL_GPL(marker_arm);
@@ -467,7 +462,7 @@ EXPORT_SYMBOL_GPL(marker_arm);
int marker_disarm(const char *name)
{
struct marker_entry *entry;
- int ret = 0, need_update = 0;
+ int ret = 0;
mutex_lock(&markers_mutex);
entry = get_marker(name);
@@ -486,11 +481,9 @@ int marker_disarm(const char *name)
ret = -EPERM;
goto end;
}
- need_update = 1;
end:
mutex_unlock(&markers_mutex);
- if (need_update)
- marker_update_probes(NULL);
+ marker_update_probes(NULL);
return ret;
}
EXPORT_SYMBOL_GPL(marker_disarm);
--
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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