On Wed, Nov 26, 2014 at 09:43:06AM -0500, Steven Rostedt wrote:
> I highly doubt it's much of a speed up. And we do that by sacrificing
> that one byte of buffer, which would lose the printk if len does equal
> TRACE_BUF_SIZE.
>
> I don't see a bug here. What exactly are you trying to fix?
Heh. vsnprintf() is going to put a NUL char at the end of the string
even if you don't plan to use it. :P
Another option would be to just print truncated output. We could use
vscnprintf() and remove the off by one limit check.
regards,
dan carpenter
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 42a822d..ab76b7b 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2160,9 +2160,7 @@ __trace_array_vprintk(struct ring_buffer *buffer,
goto out;
}
- len = vsnprintf(tbuffer, TRACE_BUF_SIZE, fmt, args);
- if (len > TRACE_BUF_SIZE)
- goto out;
+ len = vscnprintf(tbuffer, TRACE_BUF_SIZE, fmt, args);
local_save_flags(flags);
size = sizeof(*entry) + len + 1;
@@ -2173,8 +2171,7 @@ __trace_array_vprintk(struct ring_buffer *buffer,
entry = ring_buffer_event_data(event);
entry->ip = ip;
- memcpy(&entry->buf, tbuffer, len);
- entry->buf[len] = '\0';
+ memcpy(&entry->buf, tbuffer, len + 1);
if (!call_filter_check_discard(call, entry, buffer, event)) {
__buffer_unlock_commit(buffer, event);
ftrace_trace_stack(buffer, flags, 6, pc);
--
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