[bug report] tracing: Have persistent ring buffer print syscalls normally

[bug report] tracing: Have persistent ring buffer print syscalls normally

[Dan Carpenter]

Hello Steven Rostedt,

Commit 25bd47a59275 ("tracing: Have persistent ring buffer print
syscalls normally") from Oct 28, 2025 (linux-next), leads to the
following Smatch static checker warning:

	kernel/trace/trace.c:4273 print_trace_fmt()
	warn: if statement not indented

kernel/trace/trace.c
    4260         if (trace_seq_has_overflowed(s))
    4261                 return TRACE_TYPE_PARTIAL_LINE;
    4262 
    4263         if (event) {
    4264                 if (tr->trace_flags & TRACE_ITER_FIELDS)
    4265                         return print_event_fields(iter, event);
    4266                 /*
    4267                  * For TRACE_EVENT() events, the print_fmt is not
    4268                  * safe to use if the array has delta offsets
    4269                  * Force printing via the fields.
    4270                  */
    4271                 if ((tr->text_delta)) {
    4272                         /* ftrace and system call events are still OK */
--> 4273                         if ((event->type > __TRACE_LAST_TYPE) &&
    4274                             !is_syscall_event(event))

I feel like there was a line of code here that was accidentally left out
of the commit.

    4275                         return print_event_fields(iter, event);

Or we could add another tab here, but my guess is there is a missing
statement.

    4276                 }
    4277                 return event->funcs->trace(iter, sym_flags, event);
    4278         }
    4279 
    4280         trace_seq_printf(s, "Unknown type %d\n", entry->type);
    4281 
    4282         return trace_handle_return(s);
    4283 }

regards,
dan carpenter

Re: [bug report] tracing: Have persistent ring buffer print syscalls normally

[Steven Rostedt]

On Fri, 31 Oct 2025 08:37:09 +0300
Dan Carpenter <dan.carpenter@linaro.org> wrote:

>     4271                 if ((tr->text_delta)) {
>     4272                         /* ftrace and system call events are still OK */
> --> 4273                         if ((event->type > __TRACE_LAST_TYPE) &&  
>     4274                             !is_syscall_event(event))
> 
> I feel like there was a line of code here that was accidentally left out
> of the commit.

Or one was added ;-)

> 
>     4275                         return print_event_fields(iter, event);
> 
> Or we could add another tab here, but my guess is there is a missing
> statement.

The commit that caused this had:

@@ -4251,10 +4268,12 @@ static enum print_line_t print_trace_fmt(struct trace_iterator *iter)
                 * safe to use if the array has delta offsets
                 * Force printing via the fields.
                 */
-               if ((tr->text_delta) &&
-                   event->type > __TRACE_LAST_TYPE)
+               if ((tr->text_delta)) {
+                       /* ftrace and system call events are still OK */
+                       if ((event->type > __TRACE_LAST_TYPE) &&
+                           !is_syscall_event(event))
                        return print_event_fields(iter, event);
-
+               }
                return event->funcs->trace(iter, sym_flags, event);
        }

I broke the original if statement into two if statements so that it would
look better when I added another conditional. I just forgot to increase the
indentation of the if block.

Thus, a new tab is needed.

Thanks,

-- Steve