diff options
| author | Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> | 2013-05-09 14:44:29 +0900 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2013-05-09 20:14:25 -0400 |
| commit | 1cf4c0732db3cd3c49cadbc60ff6bda08604e6fa (patch) | |
| tree | 74133737a3ecea18847788c10fae7bb474f1aaa8 /kernel | |
| parent | 30052170dcc256c18a43fb3e76577a67394543f8 (diff) | |
tracing: Modify soft-mode only if there's no other referrer
Modify soft-mode flag only if no other soft-mode referrer
(currently only the ftrace triggers) by using a reference
counter in each ftrace_event_file.
Without this fix, adding and removing several different
enable/disable_event triggers on the same event clear
soft-mode bit from the ftrace_event_file. This also
happens with a typo of glob on setting triggers.
e.g.
# echo vfs_symlink:enable_event:net:netif_rx > set_ftrace_filter
# cat events/net/netif_rx/enable
0*
# echo typo_func:enable_event:net:netif_rx > set_ftrace_filter
# cat events/net/netif_rx/enable
0
# cat set_ftrace_filter
#### all functions enabled ####
vfs_symlink:enable_event:net:netif_rx:unlimited
As above, we still have a trigger, but soft-mode is gone.
Link: http://lkml.kernel.org/r/20130509054429.30398.7464.stgit@mhiramat-M0-7522
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: David Sharp <dhsharp@google.com>
Cc: Hiraku Toyooka <hiraku.toyooka.gu@hitachi.com>
Cc: Tom Zanussi <tom.zanussi@intel.com>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/trace_events.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 915c136d7bd1..8be1224046f8 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -251,7 +251,8 @@ static int __ftrace_event_enable_disable(struct ftrace_event_file *file, switch (enable) { case 0: /* - * When soft_disable is set and enable is cleared, we want + * When soft_disable is set and enable is cleared, the sm_ref + * reference counter is decremented. If it reaches 0, we want * to clear the SOFT_DISABLED flag but leave the event in the * state that it was. That is, if the event was enabled and * SOFT_DISABLED isn't set, then do nothing. But if SOFT_DISABLED @@ -263,6 +264,8 @@ static int __ftrace_event_enable_disable(struct ftrace_event_file *file, * "soft enable"s (clearing the SOFT_DISABLED bit) wont work. */ if (soft_disable) { + if (atomic_dec_return(&file->sm_ref) > 0) + break; disable = file->flags & FTRACE_EVENT_FL_SOFT_DISABLED; clear_bit(FTRACE_EVENT_FL_SOFT_MODE_BIT, &file->flags); } else @@ -291,8 +294,11 @@ static int __ftrace_event_enable_disable(struct ftrace_event_file *file, */ if (!soft_disable) clear_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &file->flags); - else + else { + if (atomic_inc_return(&file->sm_ref) > 1) + break; set_bit(FTRACE_EVENT_FL_SOFT_MODE_BIT, &file->flags); + } if (!(file->flags & FTRACE_EVENT_FL_ENABLED)) { @@ -1540,6 +1546,7 @@ __trace_add_new_event(struct ftrace_event_call *call, file->event_call = call; file->tr = tr; + atomic_set(&file->sm_ref, 0); list_add(&file->list, &tr->events); return event_create_dir(tr->event_dir, file, id, enable, filter, format); @@ -1562,6 +1569,7 @@ __trace_early_add_new_event(struct ftrace_event_call *call, file->event_call = call; file->tr = tr; + atomic_set(&file->sm_ref, 0); list_add(&file->list, &tr->events); return 0; |