lkml.org 
[lkml]   [2009]   [Apr]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Subject[PATCH] tracing/filters: protect current event filter users from filter removal
From
Date
This patch allows event filters to be removed even if tracing is active.

Signed-off-by: Tom Zanussi <tzanussi@gmail.com>

---
kernel/trace/trace.h | 9 +++++++--
kernel/trace/trace_events_filter.c | 15 +++++++++------
kernel/trace/trace_events_stage_3.h | 3 +--
3 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 9dcbc97..6bd728f 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -847,7 +847,7 @@ 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_free_preds(struct ftrace_event_call *call);
-extern int filter_match_preds(struct ftrace_event_call *call, void *rec);
+extern int filter_match_preds(struct filter_pred **preds, void *rec);
extern void filter_free_subsystem_preds(struct event_subsystem *system);
extern int filter_add_subsystem_pred(struct event_subsystem *system,
struct filter_pred *pred);
@@ -856,8 +856,13 @@ static inline void
filter_check_discard(struct ftrace_event_call *call, void *rec,
struct ring_buffer_event *event)
{
- if (unlikely(call->preds) && !filter_match_preds(call, rec))
+ struct filter_pred **preds;
+
+ rcu_read_lock();
+ preds = rcu_dereference(call->preds);
+ if (unlikely(preds) && !filter_match_preds(preds, rec))
ring_buffer_event_discard(event);
+ rcu_read_unlock();
}

#define __common_field(type, item) \
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 470ad94..f7f8469 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -83,14 +83,14 @@ static int filter_pred_string(struct filter_pred *pred, void *event)
}

/* return 1 if event matches, 0 otherwise (discard) */
-int filter_match_preds(struct ftrace_event_call *call, void *rec)
+int filter_match_preds(struct filter_pred **preds, void *rec)
{
int i, matched, and_failed = 0;
struct filter_pred *pred;

for (i = 0; i < MAX_FILTER_PRED; i++) {
- if (call->preds[i]) {
- pred = call->preds[i];
+ if (preds[i]) {
+ pred = preds[i];
if (and_failed && !pred->or)
continue;
matched = pred->fn(pred, rec);
@@ -162,13 +162,16 @@ void filter_free_pred(struct filter_pred *pred)

void filter_free_preds(struct ftrace_event_call *call)
{
+ struct filter_pred **preds;
int i;

if (call->preds) {
+ preds = call->preds;
+ rcu_assign_pointer(call->preds, NULL);
+ synchronize_rcu();
for (i = 0; i < MAX_FILTER_PRED; i++)
- filter_free_pred(call->preds[i]);
- kfree(call->preds);
- call->preds = NULL;
+ filter_free_pred(preds[i]);
+ kfree(preds);
}
}

diff --git a/kernel/trace/trace_events_stage_3.h b/kernel/trace/trace_events_stage_3.h
index 9d2fa78..cca3843 100644
--- a/kernel/trace/trace_events_stage_3.h
+++ b/kernel/trace/trace_events_stage_3.h
@@ -222,8 +222,7 @@ static void ftrace_raw_event_##call(proto) \
\
assign; \
\
- if (call->preds && !filter_match_preds(call, entry)) \
- ring_buffer_event_discard(event); \
+ filter_check_discard(call, entry, event); \
\
trace_nowake_buffer_unlock_commit(event, irq_flags, pc); \
\
--
1.5.6.3




\
 
 \ /
  Last update: 2009-04-02 08:31    [W:0.045 / U:1.912 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site