Re: [PATCH v2 1/2] tracing/events: make __string() more general

[Christoph Hellwig <hch@infradead.org>]

On Wed, May 27, 2009 at 04:12:34PM +0800, Li Zefan wrote:
> >         TP_fast_assign(
> > 		__entry->ino = args->dp->i_ino;
> > 		if (args->namelen)
> > 			memcpy(__entry->name, args->name,
> > 			       min(args->namelen, TRACE_MAXNAMELEN));
> 
> This string is not NULL-terminated?

As written a little above it's indeed not NULL-terminated.

> Then the above code can be rewrote:
> 
> TRACE_EVENT(xfs_dir2,
> 	TP_PROTO(struct xfs_da_args *args, int i, int j, int count),
> 	TP_ARGS(args, i, j, count),
> 
> 	TP_STRUCT__entry(
> 		__field(xfs_ino_t, ino)
> 		__string(name, args->namelen)
> 		__field(int, namelen)
> 		...
> 	),
> 
>         TP_fast_assign(
> 		__entry->ino = args->dp->i_ino;
> 		memcpy(__fetch_str(name), args->name, args->namelen);
> 		__entry->namelen = args->namelen;
> 		...
> 	),
> 
> 	TP_printk("ino 0x%lld %pF name %.*s namelen %d hashval 0x%x "
> 		  "inumber 0x%llx op_flags %s i %d j %d count %d",
> 		  __entry->ino,
> 		  (void *)__entry->caller_ip,
> 		  __entry->namelen,
> 		  __get_str(name),
> 		  __entry->namelen,

That's indeed wht I would love to see.