It's wasteful to call vsnprintf() only to figure out the length of the string. The string might fit in the available buffer space but we have to vsnprintf() again to do that.
Instead, attempt to format the string to the available buffer at the same time as finding the string length. Only if the string didn't fit the available space is it necessary to extend the log and format the string again to a new fragment buffer.
Signed-off-by: Richard Fitzgerald rf@opensource.cirrus.com --- lib/kunit/test.c | 33 +++++++++++++++++---------------- 1 file changed, 17 insertions(+), 16 deletions(-)
diff --git a/lib/kunit/test.c b/lib/kunit/test.c index b00f077314e3..e7f0a46d184a 100644 --- a/lib/kunit/test.c +++ b/lib/kunit/test.c @@ -196,11 +196,21 @@ void kunit_log_append(struct list_head *log, const char *fmt, ...) if (!log) return;
- /* Evaluate length of line to add to log */ + frag = list_last_entry(log, struct kunit_log_frag, list); + log_len = strlen(frag->buf); + len_left = sizeof(frag->buf) - log_len - 1; + + /* Attempt to print formatted line to current fragment */ va_start(args, fmt); - len = vsnprintf(NULL, 0, fmt, args) + 1; + len = vsnprintf(frag->buf + log_len, len_left, fmt, args) + 1; va_end(args);
+ if (len <= len_left) + goto out_newline; + + /* Abandon the truncated result of vsnprintf */ + frag->buf[log_len] = '\0'; + if (len > sizeof(frag->buf) - 1) { va_start(args, fmt); tmp = kvasprintf(GFP_KERNEL, fmt, args); @@ -212,24 +222,15 @@ void kunit_log_append(struct list_head *log, const char *fmt, ...) return; }
- frag = list_last_entry(log, struct kunit_log_frag, list); - log_len = strlen(frag->buf); - len_left = sizeof(frag->buf) - log_len - 1; - - if (len > len_left) { - frag = kunit_log_extend(log); - if (!frag) - return; - - len_left = sizeof(frag->buf) - 1; - log_len = 0; - } + frag = kunit_log_extend(log); + if (!frag) + return;
/* Print formatted line to the log */ va_start(args, fmt); - vsnprintf(frag->buf + log_len, min(len, len_left), fmt, args); + vsnprintf(frag->buf, sizeof(frag->buf) - 1, fmt, args); va_end(args); - +out_newline: /* Add newline to end of log if not already present. */ kunit_log_newline(frag); }