[PATCH] xhci: Do not open code __print_symbolic() in xhci trace events

[PATCH] xhci: Do not open code __print_symbolic() in xhci trace events

[Steven Rostedt]

From: Steven Rostedt (VMware) <rostedt@goodmis.org>

libtraceevent (used by perf and trace-cmd) failed to parse the
xhci_urb_dequeue trace event. This is because the user space trace
event format parsing is not a full C compiler. It can handle some basic
logic, but is not meant to be able to handle everything C can do.

In cases where a trace event field needs to be converted from a number
to a string, there's the __print_symbolic() macro that should be used:

 See samples/trace_events/trace-events-sample.h

Some xhci trace events open coded the __print_symbolic() causing the
user spaces tools to fail to parse it. This has to be replaced with
__print_symbolic() instead.

CC: stable@vger.kernel.org
Reported-by: Tzvetomir Stoyanov <tstoyanov@vmware.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=206531
Fixes: 5abdc2e6e12ff ("usb: host: xhci: add urb_enqueue/dequeue/giveback tracers")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
diff --git a/drivers/usb/host/xhci-trace.h b/drivers/usb/host/xhci-trace.h
index 56eb867803a6..b19582b2a72c 100644
--- a/drivers/usb/host/xhci-trace.h
+++ b/drivers/usb/host/xhci-trace.h
@@ -289,23 +289,12 @@ DECLARE_EVENT_CLASS(xhci_log_urb,
 	),
 	TP_printk("ep%d%s-%s: urb %p pipe %u slot %d length %d/%d sgs %d/%d stream %d flags %08x",
 			__entry->epnum, __entry->dir_in ? "in" : "out",
-			({ char *s;
-			switch (__entry->type) {
-			case USB_ENDPOINT_XFER_INT:
-				s = "intr";
-				break;
-			case USB_ENDPOINT_XFER_CONTROL:
-				s = "control";
-				break;
-			case USB_ENDPOINT_XFER_BULK:
-				s = "bulk";
-				break;
-			case USB_ENDPOINT_XFER_ISOC:
-				s = "isoc";
-				break;
-			default:
-				s = "UNKNOWN";
-			} s; }), __entry->urb, __entry->pipe, __entry->slot_id,
+			__print_symbolic(__entry->type,
+				   { USB_ENDPOINT_XFER_INT,	"intr" },
+				   { USB_ENDPOINT_XFER_CONTROL,	"control" },
+				   { USB_ENDPOINT_XFER_BULK,	"bulk" },
+				   { USB_ENDPOINT_XFER_ISOC,	"isoc" }),
+			__entry->urb, __entry->pipe, __entry->slot_id,
 			__entry->actual, __entry->length, __entry->num_mapped_sgs,
 			__entry->num_sgs, __entry->stream, __entry->flags
 		)

Re: [PATCH] xhci: Do not open code __print_symbolic() in xhci trace events

[Mathias Nyman]

On 14.2.2020 18.56, Steven Rostedt wrote:
> From: Steven Rostedt (VMware) <rostedt@goodmis.org>
> 
> libtraceevent (used by perf and trace-cmd) failed to parse the
> xhci_urb_dequeue trace event. This is because the user space trace
> event format parsing is not a full C compiler. It can handle some basic
> logic, but is not meant to be able to handle everything C can do.
> 
> In cases where a trace event field needs to be converted from a number
> to a string, there's the __print_symbolic() macro that should be used:
> 
>  See samples/trace_events/trace-events-sample.h
> 
> Some xhci trace events open coded the __print_symbolic() causing the
> user spaces tools to fail to parse it. This has to be replaced with
> __print_symbolic() instead.
> 
> CC: stable@vger.kernel.org
> Reported-by: Tzvetomir Stoyanov <tstoyanov@vmware.com>
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=206531
> Fixes: 5abdc2e6e12ff ("usb: host: xhci: add urb_enqueue/dequeue/giveback tracers")
> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
> ---

Thanks
Added to queue

-Mathias