From: Pavel Tikhomirov <ptikhomirov@xxxxxxxxxxxxx>
Then tracing syscall exit event it is extremely useful to filter exit
codes equal to some negative value, to react only to required errors.
But negative numbers does not work:
[root@snorch sys_exit_read]# echo "ret == -1" > filter
bash: echo: write error: Invalid argument
[root@snorch sys_exit_read]# cat filter
ret == -1
^
parse_error: Invalid value (did you forget quotes)?
Similar thing happens when setting triggers.
These is a regression in v4.17 introduced by the commit mentioned below,
testing without these commit shows no problem with negative numbers.
Link: http://lkml.kernel.org/r/20180823102534.7642-1-ptikhomirov@xxxxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 80765597bc58 ("tracing: Rewrite filter logic to be simpler and faster")
Signed-off-by: Pavel Tikhomirov <ptikhomirov@xxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
kernel/trace/trace_events_filter.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 27821480105e..217ef481fbbb 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -1301,7 +1301,7 @@ static int parse_pred(const char *str, void *data,
/* go past the last quote */
i++;
- } else if (isdigit(str[i])) {
+ } else if (isdigit(str[i]) || str[i] == '-') {
/* Make sure the field is not a string */
if (is_string_field(field)) {
@@ -1314,6 +1314,9 @@ static int parse_pred(const char *str, void *data,
goto err_free;
}
+ if (str[i] == '-')
+ i++;
+
/* We allow 0xDEADBEEF */
while (isalnum(str[i]))
i++;
--
2.20.1
