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tracing/filters: add filter_mutex to protect filter predicates

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This patch adds a filter_mutex to prevent the filter predicates from
being accessed concurrently by various external functions.

It's based on a previous patch by Li Zefan:
        "[PATCH 7/7] tracing/filters: make filter preds RCU safe"

v2 changes:

- fixed wrong value returned in a add_subsystem_pred() failure case
  noticed by Li Zefan.

[ Impact: fix trace filter corruption/crashes on parallel access ]

Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Tested-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: paulmck@linux.vnet.ibm.com
LKML-Reference: <1239946028.6639.13.camel@tropicana>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Tom Zanussi 2009-04-17 00:27:08 -05:00 • committed by Ingo Molnar
commit ac1adc55fc
3 changed files with 75 additions and 23 deletions
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4
kernel/trace/trace.h
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@ -757,13 +757,15 @@ struct filter_pred {
};
extern void filter_free_pred(struct filter_pred *pred);
extern void filter_print_preds(struct filter_pred **preds, int n_preds,
extern void filter_print_preds(struct ftrace_event_call *call,
struct trace_seq *s);
extern int filter_parse(char **pbuf, struct filter_pred *pred);
extern int filter_add_pred(struct ftrace_event_call *call,
struct filter_pred *pred);
extern void filter_disable_preds(struct ftrace_event_call *call);
extern void filter_free_subsystem_preds(struct event_subsystem *system);
extern void filter_print_subsystem_preds(struct event_subsystem *system,
struct trace_seq *s);
extern int filter_add_subsystem_pred(struct event_subsystem *system,
struct filter_pred *pred);