From: Oleg Nesterov <[email protected]>
Change trace_remove_event_call(call) to return the error if this
call is active. This is what the callers assume but can't verify
outside of the tracing locks. Both trace_kprobe.c/trace_uprobe.c
need the additional changes, unregister_trace_probe() should abort
if trace_remove_event_call() fails.
We also check TRACE_EVENT_FL_REF_MASK to ensure that nobody opened
the files we are going to remove, these means that nobody can access
the soon-to-be-freed ftrace_event_file/call via filp->private_data.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Oleg Nesterov <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>
---
include/linux/ftrace_event.h | 2 +-
kernel/trace/trace_events.c | 33 +++++++++++++++++++++++++++++++--
2 files changed, 32 insertions(+), 3 deletions(-)
diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 72ff2c6..bdf6bdd 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -338,7 +338,7 @@ extern int trace_define_field(struct ftrace_event_call *call, const char *type,
const char *name, int offset, int size,
int is_signed, int filter_type);
extern int trace_add_event_call(struct ftrace_event_call *call);
-extern void trace_remove_event_call(struct ftrace_event_call *call);
+extern int trace_remove_event_call(struct ftrace_event_call *call);
#define is_signed_type(type) (((type)(-1)) < (type)1)
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 90cf243..1a5547e 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1766,16 +1766,45 @@ static void __trace_remove_event_call(struct ftrace_event_call *call)
destroy_preds(call);
}
+static int probe_remove_event_call(struct ftrace_event_call *call)
+{
+ struct trace_array *tr;
+ struct ftrace_event_file *file;
+
+ if (call->flags & TRACE_EVENT_FL_REF_MASK)
+ return -EBUSY;
+
+#ifdef CONFIG_PERF_EVENTS
+ if (call->perf_refcount)
+ return -EBUSY;
+#endif
+ do_for_each_event_file(tr, file) {
+ if (file->event_call != call)
+ continue;
+ if (file->flags & FTRACE_EVENT_FL_ENABLED)
+ return -EBUSY;
+ break;
+ } while_for_each_event_file();
+
+ __trace_remove_event_call(call);
+
+ return 0;
+}
+
/* Remove an event_call */
-void trace_remove_event_call(struct ftrace_event_call *call)
+int trace_remove_event_call(struct ftrace_event_call *call)
{
+ int ret;
+
mutex_lock(&trace_types_lock);
mutex_lock(&event_mutex);
down_write(&trace_event_sem);
- __trace_remove_event_call(call);
+ ret = probe_remove_event_call(call);
up_write(&trace_event_sem);
mutex_unlock(&event_mutex);
mutex_unlock(&trace_types_lock);
+
+ return ret;
}
#define for_each_event(event, start, end) \
--
1.7.10.4
(2013/07/04 12:33), Steven Rostedt wrote:
> From: Oleg Nesterov <[email protected]>
>
> Change trace_remove_event_call(call) to return the error if this
> call is active. This is what the callers assume but can't verify
> outside of the tracing locks. Both trace_kprobe.c/trace_uprobe.c
> need the additional changes, unregister_trace_probe() should abort
> if trace_remove_event_call() fails.
>
> We also check TRACE_EVENT_FL_REF_MASK to ensure that nobody opened
> the files we are going to remove, these means that nobody can access
> the soon-to-be-freed ftrace_event_file/call via filp->private_data.
>
> Link: http://lkml.kernel.org/r/[email protected]
This looks good for me ;)
Reviewed-by: Masami Hiramatsu <[email protected]>
Thanks!
>
> Signed-off-by: Oleg Nesterov <[email protected]>
> Signed-off-by: Steven Rostedt <[email protected]>
> ---
> include/linux/ftrace_event.h | 2 +-
> kernel/trace/trace_events.c | 33 +++++++++++++++++++++++++++++++--
> 2 files changed, 32 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
> index 72ff2c6..bdf6bdd 100644
> --- a/include/linux/ftrace_event.h
> +++ b/include/linux/ftrace_event.h
> @@ -338,7 +338,7 @@ extern int trace_define_field(struct ftrace_event_call *call, const char *type,
> const char *name, int offset, int size,
> int is_signed, int filter_type);
> extern int trace_add_event_call(struct ftrace_event_call *call);
> -extern void trace_remove_event_call(struct ftrace_event_call *call);
> +extern int trace_remove_event_call(struct ftrace_event_call *call);
>
> #define is_signed_type(type) (((type)(-1)) < (type)1)
>
> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
> index 90cf243..1a5547e 100644
> --- a/kernel/trace/trace_events.c
> +++ b/kernel/trace/trace_events.c
> @@ -1766,16 +1766,45 @@ static void __trace_remove_event_call(struct ftrace_event_call *call)
> destroy_preds(call);
> }
>
> +static int probe_remove_event_call(struct ftrace_event_call *call)
> +{
> + struct trace_array *tr;
> + struct ftrace_event_file *file;
> +
> + if (call->flags & TRACE_EVENT_FL_REF_MASK)
> + return -EBUSY;
> +
> +#ifdef CONFIG_PERF_EVENTS
> + if (call->perf_refcount)
> + return -EBUSY;
> +#endif
> + do_for_each_event_file(tr, file) {
> + if (file->event_call != call)
> + continue;
> + if (file->flags & FTRACE_EVENT_FL_ENABLED)
> + return -EBUSY;
> + break;
> + } while_for_each_event_file();
> +
> + __trace_remove_event_call(call);
> +
> + return 0;
> +}
> +
> /* Remove an event_call */
> -void trace_remove_event_call(struct ftrace_event_call *call)
> +int trace_remove_event_call(struct ftrace_event_call *call)
> {
> + int ret;
> +
> mutex_lock(&trace_types_lock);
> mutex_lock(&event_mutex);
> down_write(&trace_event_sem);
> - __trace_remove_event_call(call);
> + ret = probe_remove_event_call(call);
> up_write(&trace_event_sem);
> mutex_unlock(&event_mutex);
> mutex_unlock(&trace_types_lock);
> +
> + return ret;
> }
>
> #define for_each_event(event, start, end) \
>
--
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: [email protected]