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| author |   Li Zefan <lizf@cn.fujitsu.com> | 2009-05-06 10:33:45 +0800 |
|---|---|---|
| committer |   Ingo Molnar <mingo@elte.hu> | 2009-05-06 10:38:19 +0200 |
| commit | 20c8928abe70e204bd077ab6cfe23002d7788983 (patch) | |
| tree | e161656f99c814ebdd69df8b5a79dab58f80065e /kernel/trace/trace_events_filter.c | |
| parent | tracing/events: fix memory leak when unloading module (diff) | |
| download | linux-dev-20c8928abe70e204bd077ab6cfe23002d7788983.tar.xz linux-dev-20c8928abe70e204bd077ab6cfe23002d7788983.zip | |
tracing/events: fix concurrent access to ftrace_events list
A module will add/remove its trace events when it gets loaded/unloaded, so
the ftrace_events list is not "const", and concurrent access needs to be
protected.
This patch thus fixes races between loading/unloding modules and read
'available_events' or read/write 'set_event', etc.
Below shows how to reproduce the race:
# for ((; ;)) { cat /mnt/tracing/available_events; } > /dev/null &
# for ((; ;)) { insmod trace-events-sample.ko; rmmod sample; } &
After a while:
BUG: unable to handle kernel paging request at 0010011c
IP: [<c1080f27>] t_next+0x1b/0x2d
...
Call Trace:
[<c10c90e6>] ? seq_read+0x217/0x30d
[<c10c8ecf>] ? seq_read+0x0/0x30d
[<c10b4c19>] ? vfs_read+0x8f/0x136
[<c10b4fc3>] ? sys_read+0x40/0x65
[<c1002a68>] ? sysenter_do_call+0x12/0x36
[ Impact: fix races when concurrent accessing ftrace_events list ]
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <4A00F709.3080800@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to '')
| -rw-r--r-- | kernel/trace/trace_events_filter.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c index ce07b8186710..7ac691085276 100644 --- a/kernel/trace/trace_events_filter.c +++ b/kernel/trace/trace_events_filter.c @@ -408,6 +408,7 @@ static void filter_free_subsystem_preds(struct event_subsystem *system) filter->n_preds = 0; } + mutex_lock(&event_mutex); list_for_each_entry(call, &ftrace_events, list) { if (!call->define_fields) continue; @@ -417,6 +418,7 @@ static void filter_free_subsystem_preds(struct event_subsystem *system) remove_filter_string(call->filter); } } + mutex_unlock(&event_mutex); } static int filter_add_pred_fn(struct filter_parse_state *ps, @@ -567,6 +569,7 @@ static int filter_add_subsystem_pred(struct filter_parse_state *ps, { struct event_filter *filter = system->filter; struct ftrace_event_call *call; + int err = 0; if (!filter->preds) { filter->preds = kzalloc(MAX_FILTER_PRED * sizeof(pred), @@ -584,8 +587,8 @@ static int filter_add_subsystem_pred(struct filter_parse_state *ps, filter->preds[filter->n_preds] = pred; filter->n_preds++; + mutex_lock(&event_mutex); list_for_each_entry(call, &ftrace_events, list) { - int err; if (!call->define_fields) continue; @@ -597,12 +600,13 @@ static int filter_add_subsystem_pred(struct filter_parse_state *ps, if (err) { filter_free_subsystem_preds(system); parse_error(ps, FILT_ERR_BAD_SUBSYS_FILTER, 0); - return err; + break; } replace_filter_string(call->filter, filter_string); } + mutex_unlock(&event_mutex); - return 0; + return err; } static void parse_init(struct filter_parse_state *ps, |