From: Steven Rostedt Impact: fix to prevent empty set_ftrace_filter and no ftrace output The function filter is used to only trace a given set of functions. The filter is enabled when a function name is echoed into the set_ftrace_filter file. But if the name has a typo and the function is not found, the filter is enabled, but no function is listed. This makes a confusing situation where set_ftrace_filter is empty but no functions ever get enabled for tracing. For example: # cat /debug/tracing/set_ftrace_filter #### all functions enabled #### # echo bad_name > set_ftrace_filter # cat /debug/tracing/set_ftrace_filter # echo function > current_tracer # cat trace # tracer: nop # # TASK-PID CPU# TIMESTAMP FUNCTION # | | | | | This patch changes that to only enable filtering if a function is set to be filtered on. Now, the filter is not enabled if a bad name is echoed into set_ftrace_filter. Signed-off-by: Steven Rostedt --- kernel/trace/ftrace.c | 14 ++++++++------ 1 files changed, 8 insertions(+), 6 deletions(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 9e60ae4..340f88b 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1153,8 +1153,6 @@ static void ftrace_match_records(char *buff, int len, int enable) /* should not be called from interrupt context */ spin_lock(&ftrace_lock); - if (enable) - ftrace_filtered = 1; do_for_each_ftrace_rec(pg, rec) { if (rec->flags & FTRACE_FL_FAILED) @@ -1166,7 +1164,12 @@ static void ftrace_match_records(char *buff, int len, int enable) else rec->flags |= flag; } - + /* + * Only enable filtering if we have a function that + * is filtered on. + */ + if (enable && (rec->flags & FTRACE_FL_FILTER)) + ftrace_filtered = 1; } while_for_each_ftrace_rec(); spin_unlock(&ftrace_lock); } @@ -1217,9 +1220,6 @@ static void ftrace_match_module_records(char *buff, char *mod, int enable) /* should not be called from interrupt context */ spin_lock(&ftrace_lock); - if (enable) - ftrace_filtered = 1; - do_for_each_ftrace_rec(pg, rec) { if (rec->flags & FTRACE_FL_FAILED) @@ -1232,6 +1232,8 @@ static void ftrace_match_module_records(char *buff, char *mod, int enable) else rec->flags |= flag; } + if (enable && (rec->flags & FTRACE_FL_FILTER)) + ftrace_filtered = 1; } while_for_each_ftrace_rec(); spin_unlock(&ftrace_lock); -- 1.5.6.5 -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/