Re: [PATCH 2/4] tracing/filters: Fix MATCH_FULL filter matching for PTR_STRING

[Frederic Weisbecker <fweisbec@gmail.com>]

On Mon, Dec 14, 2009 at 09:40:56AM +0800, Li Zefan wrote:
> Frederic Weisbecker wrote:
> > On Fri, Dec 11, 2009 at 05:59:06PM +0800, Li Zefan wrote:
> >> MATCH_FULL matching for PTR_STRING is not working correctly:
> >>
> >>   # echo 'func == vt' > events/bkl/lock_kernel/filter
> >>   # echo 1 > events/bkl/lock_kernel/enable
> >>   ...
> >>   # cat trace
> >>    Xorg-1484  [000]  1973.392586: lock_kernel: ... func=vt_ioctl()
> >>     gpm-1402  [001]  1974.027740: lock_kernel: ... func=vt_ioctl()
> >>
> >> We should pass to regex.match(..., len) the length (including '\0')
> >> of the source string instead of the length of the pattern string.
> >>
> >> Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
> > 
> > This patch is cool but it seems to also break middle and end
> > matching (at least what was working with end matching :)
> > 
> 
> No, it won't, unless I miss something.
> 
> I changed what value ptr_string passes the length param to match(),
> but this param is not used in match_middle and match_end.
> 
> It does break match_front for ptr_string, but that's because
> the mixture of 2 bugs happened to make things right. I can
> sort this out by reordering the 2 patches.


I made a mistake. I meant it breaks match front. As previously it
was taking the pattern length as a parameter and now it takes
the string length to compare.

But well, the things were so broken already that I'm not sure
we need bisectable deltas... :)