On Wed, Aug 9, 2023 at 10:54 AM Richard Fitzgerald rf@opensource.cirrus.com wrote:
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
Hello!
I find this version slightly more confusing but I realize that the extra vsnprintf() call is unnecessary. So I am ok with this version except for one question below.
I am curious what David Gow thinks and it would also be good to have another set of eyes here.
My testing of this showed no problems.
Thanks! -Rae
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 28d0048d6171..230ec5e9824f 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);
Are we meant to be using the remainder of the last fragment to its capacity or just start again with a new fragment and leave some of the last fragment empty? I worry we abandoned using the last fragment or is that the intention? Let me know if I understand this correctly.
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); } -- 2.30.2