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 <o...@redhat.com>
---
fs/coredump.c | 28 +++++++++++-----------------
1 files changed, 11 insertions(+), 17 deletions(-)
diff --git a/fs/coredump.c b/fs/coredump.c
index c10a43a..2b1d1f5 100644
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -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;
-
- ret = expand_corename(cn);
- if (ret)
- goto expand_fail;
+ int free, need;
+
+again:
+ free = cn->size - cn->used;
+ need = vsnprintf(cn->corename + cn->used, free, fmt, arg);
+ if (need < free) {
+ cn->used += need;
+ return 0;
+ }
-out_printf:
- cur = cn->corename + cn->used;
- vsnprintf(cur, need + 1, fmt, arg);
- cn->used += need;
- return 0;
+ if (!expand_corename(cn))
+ goto again;
-expand_fail:
- return ret;
+ return -ENOMEM;
}
static int cn_printf(struct core_name *cn, const char *fmt, ...)
--
1.5.5.1
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