Commit 5fe9d8ca authored Jul 03, 2013 by Oleg Nesterov Committed by Linus Torvalds Jul 03, 2013

coredump: cn_vprintf() has no reason to call vsnprintf() twice

cn_vprintf() looks really overcomplicated and sub-optimal.  We do not need
vsnprintf(NULL) to calculate the size we need, we can simply try to print
into the current buffer and expand/retry only if necessary.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Colin Walters <walters@verbum.org>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Lennart Poettering <mzxreary@0pointer.de>
Cc: Lucas De Marchi <lucas.de.marchi@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent bc03c691

fs/coredump.c

+12 −18

Original line number	Diff line number	Diff line
		@@ -71,26 +71,20 @@ static int expand_corename(struct core_name *cn)

		static int cn_vprintf(struct core_name cn, const char fmt, va_list arg)
		{
		char *cur;
		int need;
		int ret;

		need = vsnprintf(NULL, 0, fmt, arg);
		if (likely(need < cn->size - cn->used - 1))
		goto out_printf;
		int free, need;

		ret = expand_corename(cn);
		if (ret)
		goto expand_fail;

		out_printf:
		cur = cn->corename + cn->used;
		vsnprintf(cur, need + 1, fmt, arg);
		again:
		free = cn->size - cn->used;
		need = vsnprintf(cn->corename + cn->used, free, fmt, arg);
		if (need < free) {
		cn->used += need;
		return 0;
		}

		expand_fail:
		return ret;
		if (!expand_corename(cn))
		goto again;

		return -ENOMEM;
		}

		static int cn_printf(struct core_name cn, const char fmt, ...)

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