On Wed, 26 Nov 2014 17:37:19 +0300 Dan Carpenter <[email protected]> wrote:
> On Wed, Nov 26, 2014 at 09:27:06AM -0500, Steven Rostedt wrote: > > On Wed, 26 Nov 2014 17:06:21 +0300 > > Dan Carpenter <[email protected]> wrote: > > > > > This check says "goto out;" if we had to truncate the string. > > > > > > The "tbuffer" buffer has TRACE_BUF_SIZE bytes. The vsnprintf() function > > > returns the number of characters (not counting the NUL char) which would > > > have been printed if there were space. If we we tried to print > > > TRACE_BUF_SIZE characters, the last character would have been truncated > > > to make space for the NUL character so we should "goto out;". > > > > > > > Oh, and the NUL character is never copied. We copy the string into the > > buffer with: > > > > memcpy(&entry->buf, tbuffer, len); > > > > Where len does not include NUL, and why we add it ourselves. > > Yeah. I noticed that. Probably we should change the memcpy() to: > > memcpy(&entry->buf, tbuffer, len + 1); > > and remove separate NUL assignment? It's a speedup! I'll do it in v2. > 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? -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
