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Message-Id: <7d9febe58f3cd7ddb14dd3c0f19e36ee929bab26.1506105045.git.tom.zanussi@linux.intel.com>
Date: Fri, 22 Sep 2017 14:58:16 -0500
From: Tom Zanussi <tom.zanussi@...ux.intel.com>
To: rostedt@...dmis.org
Cc: tglx@...utronix.de, mhiramat@...nel.org, namhyung@...nel.org,
vedang.patel@...el.com, bigeasy@...utronix.de,
joel.opensrc@...il.com, joelaf@...gle.com,
mathieu.desnoyers@...icios.com, baohong.liu@...el.com,
rajvi.jingar@...el.com, linux-kernel@...r.kernel.org,
linux-rt-users@...r.kernel.org
Subject: [PATCH 2/9] tracing: Reverse the order of trace_types_lock and event_mutex
From: "Steven Rostedt (VMware)" <rostedt@...dmis.org>
In order to make future changes where we need to call
tracing_set_clock() from within an event command, the order of
trace_types_lock and event_mutex must be reversed, as the event command
will hold event_mutex and the trace_types_lock is taken from within
tracing_set_clock().
Requested-by: Tom Zanussi <tom.zanussi@...ux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
---
kernel/trace/trace.c | 5 +++++
kernel/trace/trace_events.c | 31 +++++++++++++++----------------
2 files changed, 20 insertions(+), 16 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 5360b7a..b0ad927 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -7674,6 +7674,7 @@ static int instance_mkdir(const char *name)
struct trace_array *tr;
int ret;
+ mutex_lock(&event_mutex);
mutex_lock(&trace_types_lock);
ret = -EEXIST;
@@ -7729,6 +7730,7 @@ static int instance_mkdir(const char *name)
list_add(&tr->list, &ftrace_trace_arrays);
mutex_unlock(&trace_types_lock);
+ mutex_unlock(&event_mutex);
return 0;
@@ -7740,6 +7742,7 @@ static int instance_mkdir(const char *name)
out_unlock:
mutex_unlock(&trace_types_lock);
+ mutex_unlock(&event_mutex);
return ret;
@@ -7752,6 +7755,7 @@ static int instance_rmdir(const char *name)
int ret;
int i;
+ mutex_lock(&event_mutex);
mutex_lock(&trace_types_lock);
ret = -ENODEV;
@@ -7797,6 +7801,7 @@ static int instance_rmdir(const char *name)
out_unlock:
mutex_unlock(&trace_types_lock);
+ mutex_unlock(&event_mutex);
return ret;
}
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 8746839..ec0f9aa 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1406,8 +1406,8 @@ static int subsystem_open(struct inode *inode, struct file *filp)
return -ENODEV;
/* Make sure the system still exists */
- mutex_lock(&trace_types_lock);
mutex_lock(&event_mutex);
+ mutex_lock(&trace_types_lock);
list_for_each_entry(tr, &ftrace_trace_arrays, list) {
list_for_each_entry(dir, &tr->systems, list) {
if (dir == inode->i_private) {
@@ -1421,8 +1421,8 @@ static int subsystem_open(struct inode *inode, struct file *filp)
}
}
exit_loop:
- mutex_unlock(&event_mutex);
mutex_unlock(&trace_types_lock);
+ mutex_unlock(&event_mutex);
if (!system)
return -ENODEV;
@@ -2294,15 +2294,15 @@ void trace_event_eval_update(struct trace_eval_map **map, int len)
int trace_add_event_call(struct trace_event_call *call)
{
int ret;
- mutex_lock(&trace_types_lock);
mutex_lock(&event_mutex);
+ mutex_lock(&trace_types_lock);
ret = __register_event(call, NULL);
if (ret >= 0)
__add_event_to_tracers(call);
- mutex_unlock(&event_mutex);
mutex_unlock(&trace_types_lock);
+ mutex_unlock(&event_mutex);
return ret;
}
@@ -2356,13 +2356,13 @@ int trace_remove_event_call(struct trace_event_call *call)
{
int ret;
- mutex_lock(&trace_types_lock);
mutex_lock(&event_mutex);
+ mutex_lock(&trace_types_lock);
down_write(&trace_event_sem);
ret = probe_remove_event_call(call);
up_write(&trace_event_sem);
- mutex_unlock(&event_mutex);
mutex_unlock(&trace_types_lock);
+ mutex_unlock(&event_mutex);
return ret;
}
@@ -2424,8 +2424,8 @@ static int trace_module_notify(struct notifier_block *self,
{
struct module *mod = data;
- mutex_lock(&trace_types_lock);
mutex_lock(&event_mutex);
+ mutex_lock(&trace_types_lock);
switch (val) {
case MODULE_STATE_COMING:
trace_module_add_events(mod);
@@ -2434,8 +2434,8 @@ static int trace_module_notify(struct notifier_block *self,
trace_module_remove_events(mod);
break;
}
- mutex_unlock(&event_mutex);
mutex_unlock(&trace_types_lock);
+ mutex_unlock(&event_mutex);
return 0;
}
@@ -2950,24 +2950,24 @@ static __init int setup_trace_event(char *str)
* creates the event hierachry in the @parent/events directory.
*
* Returns 0 on success.
+ *
+ * Must be called with event_mutex held.
*/
int event_trace_add_tracer(struct dentry *parent, struct trace_array *tr)
{
int ret;
- mutex_lock(&event_mutex);
+ lockdep_assert_held(&event_mutex);
ret = create_event_toplevel_files(parent, tr);
if (ret)
- goto out_unlock;
+ goto out;
down_write(&trace_event_sem);
__trace_add_event_dirs(tr);
up_write(&trace_event_sem);
- out_unlock:
- mutex_unlock(&event_mutex);
-
+ out:
return ret;
}
@@ -2996,9 +2996,10 @@ int event_trace_add_tracer(struct dentry *parent, struct trace_array *tr)
return ret;
}
+/* Must be called with event_mutex held */
int event_trace_del_tracer(struct trace_array *tr)
{
- mutex_lock(&event_mutex);
+ lockdep_assert_held(&event_mutex);
/* Disable any event triggers and associated soft-disabled events */
clear_event_triggers(tr);
@@ -3019,8 +3020,6 @@ int event_trace_del_tracer(struct trace_array *tr)
tr->event_dir = NULL;
- mutex_unlock(&event_mutex);
-
return 0;
}
--
1.9.3
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