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tracing: Clear all trace buffers when unloaded module event was used

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Currently we do not know what buffer a module event was enabled in.
On unload, it is safest to clear all buffer instances, not just the
top level buffer.

Todo: Clear only the buffer that the event was used in. The
infrastructure is there to do this, but it makes the code a bit
more complex. Lets get the current code vetted before we add that.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (Red Hat) 2013-03-04 23:26:06 -05:00 committed by Steven Rostedt
parent 575380da8b
commit 873c642f59
3 changed files with 16 additions and 6 deletions
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10
kernel/trace/trace.c
View file

@ -912,9 +912,15 @@ void tracing_reset_current(int cpu)
tracing_reset(&global_trace, cpu);
}
void tracing_reset_current_online_cpus(void)
void tracing_reset_all_online_cpus(void)
{
tracing_reset_online_cpus(&global_trace);
struct trace_array *tr;
mutex_lock(&trace_types_lock);
list_for_each_entry(tr, &ftrace_trace_arrays, list) {
tracing_reset_online_cpus(tr);
}
mutex_unlock(&trace_types_lock);
}
#define SAVED_CMDLINES 128

2
kernel/trace/trace.h
View file

@ -496,7 +496,7 @@ int tracing_is_enabled(void);
void tracing_reset(struct trace_array *tr, int cpu);
void tracing_reset_online_cpus(struct trace_array *tr);
void tracing_reset_current(int cpu);
void tracing_reset_current_online_cpus(void);
void tracing_reset_all_online_cpus(void);
int tracing_open_generic(struct inode *inode, struct file *filp);
struct dentry *trace_create_file(const char *name,
umode_t mode,

10
kernel/trace/trace_events.c
View file

@ -1649,14 +1649,18 @@ static void trace_module_remove_events(struct module *mod)
list_del(&file_ops->list);
kfree(file_ops);
}
up_write(&trace_event_mutex);
/*
* It is safest to reset the ring buffer if the module being unloaded
* registered any events that were used.
* registered any events that were used. The only worry is if
* a new module gets loaded, and takes on the same id as the events
* of this module. When printing out the buffer, traced events left
* over from this module may be passed to the new module events and
* unexpected results may occur.
*/
if (clear_trace)
tracing_reset_current_online_cpus();
up_write(&trace_event_mutex);
tracing_reset_all_online_cpus();
}
static int trace_module_notify(struct notifier_block *self,