On Mon, 22 Apr 2024 14:55:25 -0700 Beau Belgrave <be...@linux.microsoft.com> wrote:
> On Sat, Apr 20, 2024 at 09:50:52PM +0900, Masami Hiramatsu wrote: > > On Fri, 19 Apr 2024 14:13:34 -0700 > > Beau Belgrave <be...@linux.microsoft.com> wrote: > > > > > On Fri, Apr 19, 2024 at 11:33:05AM +0900, Masami Hiramatsu wrote: > > > > On Tue, 16 Apr 2024 22:41:01 +0000 > > > > Beau Belgrave <be...@linux.microsoft.com> wrote: > > *SNIP* > > > > > nit: This loop can be simpler, because we are sure fixed has enough > > > > length; > > > > > > > > /* insert a space after ';' if there is no space. */ > > > > while(*args) { > > > > *pos = *args++; > > > > if (*pos++ == ';' && !isspace(*args)) > > > > *pos++ = ' '; > > > > } > > > > > > > > > > I was worried that if count_semis_no_space() ever had different logic > > > (maybe after this commit) that it could cause an overflow if the count > > > was wrong, etc. > > > > > > I don't have an issue making it shorter, but I was trying to be more on > > > the safe side, since this isn't a fast path (event register). > > > > OK, anyway current code looks correct. But note that I don't think > > "pos++; len--;" is safer, since it is not atomic. This pattern > > easily loose "len--;" in my experience. So please carefully use it ;) > > > > I'll stick with your loop. Perhaps others will chime in on the v2 and > state a stronger opinion. > > You scared me with the atomic comment, I went back and looked at all the > paths for this. In the user_events IOCTL the buffer is copied from user > to kernel, so it cannot change (and no other threads access it). I also > checked trace_parse_run_command() which is the same. So at least in this > context the non-atomic part is OK. Oh, sorry if I scared you. I've seen bugs get introduced into loops like this many times (while updating the code), so I try to keep it simple. I'm sure that your code has no bugs. Thank you, -- Masami Hiramatsu (Google) <mhira...@kernel.org>