batman-adv: tracing: 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/[e-mail]

Cc: Marek Lindner <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Andrew Morton <[e-mail]>
Cc: Simon Wunderlich <[e-mail]>
Cc: Antonio Quartulli <[e-mail]>
Cc: "David S. Miller" <[e-mail]>
Cc: Eric Dumazet <[e-mail]>
Cc: Jakub Kicinski <[e-mail]>
Cc: Paolo Abeni <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Acked-by: Sven Eckelmann <[e-mail]>
Signed-off-by: Steven Rostedt (Google) <[e-mail]>

net/batman-adv/trace.h

···
 
 #endif /* CONFIG_BATMAN_ADV_TRACING */
 
-#define BATADV_MAX_MSG_LEN	256
-
 TRACE_EVENT(batadv_dbg,
 
 	    TP_PROTO(struct batadv_priv *bat_priv,
···
 	    TP_STRUCT__entry(
 		    __string(device, bat_priv->soft_iface->name)
 		    __string(driver, KBUILD_MODNAME)
-		    __dynamic_array(char, msg, BATADV_MAX_MSG_LEN)
+		    __vstring(msg, vaf->fmt, vaf->va)
 	    ),
 
 	    TP_fast_assign(
 		    __assign_str(device, bat_priv->soft_iface->name);
 		    __assign_str(driver, KBUILD_MODNAME);
-		    WARN_ON_ONCE(vsnprintf(__get_dynamic_array(msg),
-					   BATADV_MAX_MSG_LEN,
-					   vaf->fmt,
-					   *vaf->va) >= BATADV_MAX_MSG_LEN);
+		    __assign_vstr(msg, vaf->fmt, vaf->va);
 	    ),
 
 	    TP_printk(