From: Pavel Tikhomirov ptikhomirov@virtuozzo.com
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@virtuozzo.com
Cc: stable@vger.kernel.org Fixes: 80765597bc58 ("tracing: Rewrite filter logic to be simpler and faster") Signed-off-by: Pavel Tikhomirov ptikhomirov@virtuozzo.com Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org --- 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++;