On Thu, 1 Apr 2021 22:03:02 +0530 sameeruddin shaik <sameeruddin.shaik8@xxxxxxxxx> wrote: > hi steve, > > On 30/03/21 6:21 am, Steven Rostedt wrote: > > From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx> > > > > All for full "regex(3)" processing of setting functions in the > > set_ftrace_filter file. Check if the filter passed in is just a glob > > expression that the kernel can process, or if it is a regex that should look > > at the available_filter_functions list instead. > > > > If it is a regex, it will read the available_filter_functions and write in > > each function as it finds it. > > > > Link: https://lore.kernel.org/linux-trace-devel/20210323013225.451281989@xxxxxxxxxxx > > > > Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> > > --- > > Documentation/libtracefs-function-filter.txt | 10 ++ > > src/tracefs-tools.c | 139 ++++++++++++++++--- > > 2 files changed, 128 insertions(+), 21 deletions(-) > > > > diff --git a/Documentation/libtracefs-function-filter.txt b/Documentation/libtracefs-function-filter.txt > > index c0c89f372c21..88aa3b923d54 100644 > > --- a/Documentation/libtracefs-function-filter.txt > > +++ b/Documentation/libtracefs-function-filter.txt > > @@ -32,6 +32,16 @@ _errs_, is a pointer to an array of strings, which will be allocated if > > any of filters fail to match any available function, If _errs_ is NULL, it will > > be ignored. > > > > +A filter in the array of _filters_ may be either a straight match of a > > +function, a glob or regex(3). a glob is where '*' matches zero or more > > +characters, '?' will match zero or one character, and '.' only matches a > > +period. If the filter is determined to be a regex (where it contains > > +anything other than alpha numeric characters, or '.', '*', '?') the filter > > +will be processed as a regex(3) following the rules of regex(3), and '.' is > > +not a period, but will match any one character. To force a regular > > +expression, either prefix the filter with a '^' or append it with a '$' as > > +all filters will act as complete matches of functions anyway. > > + > > if we give the filter as regex "^ext4*$" from user side, ideally it > should match the ext4 filter functions, if i am not wrong, its not > matching any filter in the available_filter_functions If you add the "^" and/or "$" it makes it into a regex. The above means that the filter will match "ext", "ext4", "ext44", "ext4444444" Because "*" means zero or more of the previous character. So, unless there's a function that matches one of the above, it wont match anything else. If you left off the "^" and "$" then it would be a glob, where "*" means zero or more of any character. But if you want the same in regex, you need to use: "^ext4.*$" > > is this expected behaviour? > > if we give the filter as glob "ext4*" from userside, its making the > regex and matching the ext4 filter functions in the > available_filter_functions. Yes, because the conversion changes the glob "ext4*" into "^ext4.*$". Also, for email etiquette, please sign you last comment, or cut the rest of the reply. That way I don't have to scroll the rest of the email to know if there's anything else you commented on. -- Steve
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