tracing/IB/hfi1: Use the new __vstring() helper

Instead of open coding a __dynamic_array() with a fixed length (which
defeats the purpose of the dynamic array in the first place). Use the new
__vstring() helper that will use a va_list and only write enough of the
string into the ring buffer that is needed.

Link: https://lkml.kernel.org/r/20220705224749.239494531@goodmis.org

Cc: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: linux-rdma@vger.kernel.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

drivers/infiniband/hw/hfi1/trace_dbg.h

@@ -26,14 +26,10 @@ DECLARE_EVENT_CLASS(hfi1_trace_template,
 		    TP_PROTO(const char *function, struct va_format *vaf),
 		    TP_ARGS(function, vaf),
 		    TP_STRUCT__entry(__string(function, function)
-				     __dynamic_array(char, msg, MAX_MSG_LEN)
+				     __vstring(msg, vaf->fmt, vaf->va)
 				     ),
 		    TP_fast_assign(__assign_str(function, function);
-				   WARN_ON_ONCE(vsnprintf
-						(__get_dynamic_array(msg),
-						 MAX_MSG_LEN, vaf->fmt,
-						 *vaf->va) >=
-						MAX_MSG_LEN);
+				   __assign_vstr(msg, vaf->fmt, vaf->va);
 				   ),
 		    TP_printk("(%s) %s",
 			      __get_str(function),