From: Petr Mladek <pmladek@suse.com>
To: Jim Cromie <jim.cromie@gmail.com>
Cc: jbaron@akamai.com, linux-kernel@vger.kernel.org,
akpm@linuxfoundation.org, gregkh@linuxfoundation.org,
linux@rasmusvillemoes.dk, Jonathan Corbet <corbet@lwn.net>,
Andrew Morton <akpm@linux-foundation.org>,
Will Deacon <will@kernel.org>, Orson Zhai <orson.zhai@unisoc.com>,
linux-doc@vger.kernel.org
Subject: Re: [PATCH v3 20/21] dyndbg: add user-flag, negating-flags, and filtering on flags
Date: Thu, 18 Jun 2020 19:40:59 +0200 [thread overview]
Message-ID: <20200618174058.GE3617@alley> (raw)
In-Reply-To: <20200618161912.GD3617@alley>
On Thu 2020-06-18 18:19:12, Petr Mladek wrote:
> On Wed 2020-06-17 10:25:35, Jim Cromie wrote:
> > 1. Add a user-flag [u] which works like the [pfmlt] flags, but has no
> > effect on callsite behavior; it allows incremental marking of
> > arbitrary sets of callsites.
> >
> > 2. Add [PFMLTU] flags, which negate their counterparts; P===!p etc.
> > And in ddebug_read_flags():
> > current code does: [pfmltu_] -> flags
> > copy it to: [PFMLTU_] -> mask
> >
> > also disallow both of a pair: ie no 'pP', no true & false.
> >
> > 3. Add filtering ops into ddebug_change(), right after all the
> > callsite-property selections are complete. These filter on the
> > callsite's current flagstate before applying modflags.
> >
> > Why ?
> >
> > The u-flag & filter flags
> >
> > The 'u' flag lets the user assemble an arbitary set of callsites.
> > Then using filter flags, user can activate the 'u' callsite set.
> >
> > #> echo 'file foo.c +u; file bar.c +u' > control # and repeat
> > #> echo 'u+p' > control
> >
> > Of course, you can continue to just activate your set without ever
> > marking it 1st, but you could trivially add the markup as you go, then
> > be able to use it as a constraint later, to undo or modify your set.
> >
> > #> echo 'file foo.c +up' >control
> > .. monitor, debug, finish ..
> > #> echo 'u-p' >control
> >
> > # then later resume
> > #> echo 'u+p' >control
> >
> > # disable some cluttering messages, and remove from u-set
> > #> echo 'file noisy.c function:jabber_* u-pu' >control
> >
> > # for doc, recollection
> > grep =pu control > my-favorite-callsites
> >
> > Note:
> >
> > Your flagstate after boot is generally not all =_. -DDEBUG will arm
> > compiled callsites by default, $builtinmod.dyndbg=+p bootargs can
> > enable them early, and $module.dyndbg=+p bootargs will arm them when
> > the module is loaded. But you could manage them with u-flags:
> >
> > #> echo '-t' >control # clear t-flag to use it as 2ndary markup
> > #> echo 'p+ut' >control # mark the boot-enabled set of callsites
> > #> echo '-p' >control # clean your dmesg -w stream
> >
> > ... monitor, debug ..
> > #> echo 'module of_interest $qterms +pu' >control # build your set of useful debugs
> > #> echo 'module of_interest $qterms UT+pu' >control # same, but dont alter ut marked set
>
> Does anyone requested this feature, please?
>
> For me, it is really hard to imagine people using these complex and hacky
> steps.
I think that all this is motivated by adding support for module
specific groups.
What about storing the group as yet another information for each
message? I mean the same way as we store module name, file, line,
function name.
Then we could add API to define group for a given message:
pr_debug_group(group_id, fmt, ...);
the interface for the control file might be via new keyword "group".
You could then do something like:
echo module=drm group=0x3 +p >control
But more importantly you should add functions that might be called
when the drm.debug parameter is changes. I have already mentioned
it is another reply:
dd_enable_module_group(module_name, group_id);
dd_disable_module_group(module_name, group_id);
It will _not_ need any new flag or flag filtering.
Best Regards,
Petr
next prev parent reply other threads:[~2020-06-18 17:41 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-17 16:25 [PATCH v3 00/21] dynamic_debug cleanups, query features, export Jim Cromie
2020-06-17 16:25 ` [PATCH v3 01/21] dyndbg-docs: eschew file /full/path query in docs Jim Cromie
2020-06-17 16:25 ` [PATCH v3 02/21] dyndbg-docs: initialization is done early, not arch Jim Cromie
2020-06-17 16:25 ` [PATCH v3 03/21] dyndbg: drop obsolete comment on ddebug_proc_open Jim Cromie
2020-06-17 16:25 ` [PATCH v3 04/21] dyndbg: refine debug verbosity; 1 is basic, 2 more chatty Jim Cromie
2020-06-17 16:25 ` [PATCH v3 05/21] dyndbg: rename __verbose section to __dyndbg Jim Cromie
2020-06-17 16:25 ` [PATCH v3 06/21] dyndbg: fix overcounting of ram used by dyndbg Jim Cromie
2020-06-17 16:25 ` [PATCH v3 07/21] dyndbg: fix a BUG_ON in ddebug_describe_flags Jim Cromie
2020-06-17 16:25 ` [PATCH v3 08/21] dyndbg: fix pr_err with empty string Jim Cromie
2020-06-17 16:25 ` [PATCH v3 09/21] dyndbg: prefer declarative init in caller, to memset in callee Jim Cromie
2020-06-17 16:25 ` [PATCH v3 10/21] dyndbg: make ddebug_tables list LIFO for add/remove_module Jim Cromie
2020-06-17 16:25 ` [PATCH v3 11/21] dyndbg: use gcc ?: to reduce word count Jim Cromie
2020-06-17 16:25 ` [PATCH v3 12/21] dyndbg: refactor parse_linerange out of ddebug_parse_query Jim Cromie
2020-06-17 16:25 ` [PATCH v3 13/21] dyndbg: accept 'file foo.c:func1' and 'file foo.c:10-100' Jim Cromie
2020-06-17 16:25 ` [PATCH v3 14/21] dyndbg: accept query terms like file=bar and module=foo Jim Cromie
2020-06-18 22:25 ` jim.cromie
2020-06-17 16:25 ` [PATCH v3 14/21] dyndbg: accept query terms like file=bar module=foo Jim Cromie
2020-06-17 16:25 ` [PATCH v3 14/21] dyndbg: accept query terms like module:foo and file=bar Jim Cromie
2020-06-17 16:25 ` [PATCH v3 15/21] dyndbg: export ddebug_exec_queries Jim Cromie
2020-06-17 16:25 ` [PATCH v3 16/21] dyndbg: combine flags & mask into a struct, simplify with it Jim Cromie
2020-06-17 16:25 ` [PATCH v3 17/21] dyndbg: refactor ddebug_read_flags out of ddebug_parse_flags Jim Cromie
2020-06-17 16:25 ` [PATCH v3 18/21] dyndbg: add filter channel to the internals Jim Cromie
2020-06-17 16:25 ` [PATCH v3 19/21] dyndbg: extend ddebug_parse_flags to accept optional leading filter-flags Jim Cromie
2020-06-18 12:44 ` Petr Mladek
2020-06-18 14:54 ` jim.cromie
2020-06-18 16:01 ` Petr Mladek
2020-06-17 16:25 ` [PATCH v3 20/21] dyndbg: add user-flag, negating-flags, and filtering on flags Jim Cromie
2020-06-17 22:13 ` Joe Perches
2020-06-17 22:57 ` jim.cromie
2020-06-18 16:19 ` Petr Mladek
2020-06-18 17:40 ` Petr Mladek [this message]
2020-06-18 18:17 ` Jason Baron
2020-06-18 19:11 ` jim.cromie
2020-06-18 19:40 ` Jason Baron
2020-06-18 21:31 ` jim.cromie
2020-06-18 22:34 ` Stanimir Varbanov
2020-06-18 22:48 ` jim.cromie
2020-06-19 16:07 ` Jason Baron
2020-06-19 7:45 ` Petr Mladek
2020-06-19 8:10 ` Petr Mladek
2020-06-19 8:34 ` Greg KH
2020-06-18 18:15 ` jim.cromie
2020-06-17 16:25 ` [PATCH v3 21/21] dyndbg: allow negating flag-chars in modifier flags Jim Cromie
2020-06-17 20:05 ` [PATCH v3 00/21] dynamic_debug cleanups, query features, export Rasmus Villemoes
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