From: Petr Mladek <pmladek@suse.com>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Miroslav Benes <mbenes@suse.cz>, Jessica Yu <jeyu@redhat.com>,
Jiri Kosina <jikos@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
live-patching@vger.kernel.org,
Michael Ellerman <mpe@ellerman.id.au>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
x86@kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-s390@vger.kernel.org, Vojtech Pavlik <vojtech@suse.com>,
Jiri Slaby <jslaby@suse.cz>,
Chris J Arges <chris.j.arges@canonical.com>,
Andy Lutomirski <luto@kernel.org>, Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH v3 13/15] livepatch: change to a per-task consistency model
Date: Tue, 10 Jan 2017 11:40:04 +0100 [thread overview]
Message-ID: <20170110104004.GG20785@pathway.suse.cz> (raw)
In-Reply-To: <20170106200734.d7wvry4upz2ffwem@treble>
On Fri 2017-01-06 14:07:34, Josh Poimboeuf wrote:
> On Fri, Dec 23, 2016 at 11:18:03AM +0100, Petr Mladek wrote:
> > On Fri 2016-12-23 10:24:35, Miroslav Benes wrote:
> > > > > > diff --git a/kernel/livepatch/patch.c b/kernel/livepatch/patch.c
> > > > > > index 5efa262..e79ebb5 100644
> > > > > > --- a/kernel/livepatch/patch.c
> > > > > > +++ b/kernel/livepatch/patch.c
> > > > > > @@ -29,6 +29,7 @@
> > > > > > #include <linux/bug.h>
> > > > > > #include <linux/printk.h>
> > > > > > #include "patch.h"
> > > > > > +#include "transition.h"
> > > > > >
> > > > > > static LIST_HEAD(klp_ops);
> > > > > >
> > > > > > @@ -54,15 +55,53 @@ static void notrace klp_ftrace_handler(unsigned long ip,
> > > > > > {
> > > > > > struct klp_ops *ops;
> > > > > > struct klp_func *func;
> > > > > > + int patch_state;
> > > > > >
> > > > > > ops = container_of(fops, struct klp_ops, fops);
> > > > > >
> > > > > > rcu_read_lock();
> > > > > > +
> > > > > > func = list_first_or_null_rcu(&ops->func_stack, struct klp_func,
> > > > > > stack_node);
> > > > > > - if (WARN_ON_ONCE(!func))
> > > > > > +
> > > > > > + if (!func)
> > > > > > goto unlock;
> > > > >
> Yeah, I'm thinking we should keep the warning to catch any bugs in case
> any of our ftrace assumptions change. Maybe I should add a comment:
>
> /*
> * func can never be NULL because preemption should be disabled
> * here and unregister_ftrace_function() does the equivalent of
> * a synchronize_sched() before the func_stack removal.
> */
> if (WARN_ON_ONCE(!func))
> goto unlock;
Sounds reasonable to me.
Best Regards,
Petr
next prev parent reply other threads:[~2017-01-10 10:40 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-08 18:08 [PATCH v3 00/15] livepatch: hybrid consistency model Josh Poimboeuf
2016-12-08 18:08 ` [PATCH v3 01/15] stacktrace/x86: add function for detecting reliable stack traces Josh Poimboeuf
2016-12-16 13:07 ` Petr Mladek
2016-12-16 22:09 ` Josh Poimboeuf
2016-12-19 16:25 ` Miroslav Benes
2016-12-19 17:25 ` Josh Poimboeuf
2016-12-19 18:23 ` Miroslav Benes
2016-12-20 9:39 ` Petr Mladek
2016-12-20 21:21 ` Josh Poimboeuf
2016-12-08 18:08 ` [PATCH v3 02/15] x86/entry: define _TIF_ALLWORK_MASK flags explicitly Josh Poimboeuf
2016-12-16 14:17 ` Petr Mladek
2016-12-16 22:13 ` Josh Poimboeuf
2016-12-19 16:39 ` Miroslav Benes
2017-01-10 8:49 ` Kamalesh Babulal
2016-12-08 18:08 ` [PATCH v3 03/15] livepatch: temporary stubs for klp_patch_pending() and klp_update_patch_state() Josh Poimboeuf
2016-12-16 14:41 ` Petr Mladek
2016-12-16 22:15 ` Josh Poimboeuf
2016-12-08 18:08 ` [PATCH v3 04/15] livepatch/x86: add TIF_PATCH_PENDING thread flag Josh Poimboeuf
2016-12-08 18:27 ` Andy Lutomirski
2016-12-16 15:39 ` Petr Mladek
2016-12-21 13:54 ` Miroslav Benes
2017-01-11 7:06 ` Kamalesh Babulal
2016-12-08 18:08 ` [PATCH v3 05/15] livepatch/powerpc: " Josh Poimboeuf
2016-12-16 16:00 ` Petr Mladek
2016-12-21 14:30 ` Miroslav Benes
2017-01-10 8:29 ` Kamalesh Babulal
2016-12-08 18:08 ` [PATCH v3 06/15] livepatch/s390: reorganize TIF thread flag bits Josh Poimboeuf
2016-12-21 15:29 ` Miroslav Benes
2016-12-08 18:08 ` [PATCH v3 07/15] livepatch/s390: add TIF_PATCH_PENDING thread flag Josh Poimboeuf
2016-12-08 18:08 ` [PATCH v3 08/15] livepatch: separate enabled and patched states Josh Poimboeuf
2016-12-16 16:21 ` Petr Mladek
2016-12-23 12:54 ` Miroslav Benes
2017-01-10 9:10 ` Kamalesh Babulal
2016-12-08 18:08 ` [PATCH v3 09/15] livepatch: remove unnecessary object loaded check Josh Poimboeuf
2016-12-16 16:26 ` Petr Mladek
2016-12-23 12:58 ` Miroslav Benes
2017-01-10 9:14 ` Kamalesh Babulal
2016-12-08 18:08 ` [PATCH v3 10/15] livepatch: move patching functions into patch.c Josh Poimboeuf
2016-12-16 16:49 ` Petr Mladek
2016-12-23 13:06 ` Miroslav Benes
2017-01-10 9:15 ` Kamalesh Babulal
2016-12-08 18:08 ` [PATCH v3 11/15] livepatch: use kstrtobool() in enabled_store() Josh Poimboeuf
2016-12-16 16:55 ` Petr Mladek
2016-12-16 22:19 ` Josh Poimboeuf
2016-12-23 13:13 ` Miroslav Benes
2016-12-08 18:08 ` [PATCH v3 12/15] livepatch: store function sizes Josh Poimboeuf
2016-12-19 13:10 ` Petr Mladek
2016-12-23 13:40 ` Miroslav Benes
2017-01-11 10:09 ` Kamalesh Babulal
2016-12-08 18:08 ` [PATCH v3 13/15] livepatch: change to a per-task consistency model Josh Poimboeuf
2016-12-20 17:32 ` Petr Mladek
2016-12-21 21:25 ` Josh Poimboeuf
2016-12-22 14:34 ` Petr Mladek
2016-12-22 18:31 ` Josh Poimboeuf
2017-01-10 13:00 ` Petr Mladek
2017-01-10 20:46 ` Josh Poimboeuf
2017-01-11 15:18 ` Petr Mladek
2017-01-11 15:26 ` Josh Poimboeuf
2016-12-23 9:24 ` Miroslav Benes
2016-12-23 10:18 ` Petr Mladek
2017-01-06 20:07 ` Josh Poimboeuf
2017-01-10 10:40 ` Petr Mladek [this message]
2017-01-04 13:44 ` Miroslav Benes
2017-01-06 21:01 ` Josh Poimboeuf
2017-01-10 10:45 ` Miroslav Benes
2017-01-05 9:34 ` Miroslav Benes
2017-01-06 21:04 ` Josh Poimboeuf
2016-12-08 18:08 ` [PATCH v3 14/15] livepatch: add /proc/<pid>/patch_state Josh Poimboeuf
2016-12-21 11:20 ` Petr Mladek
2017-01-04 14:50 ` Miroslav Benes
2016-12-08 18:08 ` [PATCH v3 15/15] livepatch: allow removal of a disabled patch Josh Poimboeuf
2016-12-21 14:44 ` Petr Mladek
2017-01-04 14:57 ` Miroslav Benes
2017-01-06 21:04 ` Josh Poimboeuf
2016-12-10 5:46 ` [PATCH v3 00/15] livepatch: hybrid consistency model Balbir Singh
2016-12-10 17:17 ` Josh Poimboeuf
2016-12-11 2:08 ` Balbir Singh
2016-12-12 14:04 ` Josh Poimboeuf
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