From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Fri, 20 Oct 2017 08:34:36 +0200 (CEST) From: Thomas Gleixner To: Bart Van Assche cc: "mingo@kernel.org" , "peterz@infradead.org" , "byungchul.park@lge.com" , "linux-kernel@vger.kernel.org" , "amir73il@gmail.com" , "linux-block@vger.kernel.org" , "hch@infradead.org" , "linux-xfs@vger.kernel.org" , "linux-mm@kvack.org" , "oleg@redhat.com" , "darrick.wong@oracle.com" , "johannes.berg@intel.com" , "linux-fsdevel@vger.kernel.org" , "idryomov@gmail.com" , "tj@kernel.org" , "kernel-team@lge.com" , "david@fromorbit.com" Subject: Re: [RESEND PATCH 1/3] completion: Add support for initializing completion with lockdep_map In-Reply-To: <1508455438.4542.4.camel@wdc.com> Message-ID: References: <1508319532-24655-1-git-send-email-byungchul.park@lge.com> <1508319532-24655-2-git-send-email-byungchul.park@lge.com> <1508455438.4542.4.camel@wdc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Thu, 19 Oct 2017, Bart Van Assche wrote: > On Wed, 2017-10-18 at 18:38 +0900, Byungchul Park wrote: > > Sometimes, we want to initialize completions with sparate lockdep maps > > to assign lock classes under control. For example, the workqueue code > > manages lockdep maps, as it can classify lockdep maps properly. > > Provided a function for that purpose. > > > > Signed-off-by: Byungchul Park > > --- > > include/linux/completion.h | 8 ++++++++ > > 1 file changed, 8 insertions(+) > > > > diff --git a/include/linux/completion.h b/include/linux/completion.h > > index cae5400..182d56e 100644 > > --- a/include/linux/completion.h > > +++ b/include/linux/completion.h > > @@ -49,6 +49,13 @@ static inline void complete_release_commit(struct completion *x) > > lock_commit_crosslock((struct lockdep_map *)&x->map); > > } > > > > +#define init_completion_with_map(x, m) \ > > +do { \ > > + lockdep_init_map_crosslock((struct lockdep_map *)&(x)->map, \ > > + (m)->name, (m)->key, 0); \ > > + __init_completion(x); \ > > +} while (0) > > Are there any completion objects for which the cross-release checking is > useful? All of them by definition. > Are there any wait_for_completion() callers that hold a mutex or > other locking object? Yes, there are also cross completion dependencies. There have been such bugs and I expect more to be unearthed. I really have to ask what your motiviation is to fight the lockdep coverage of synchronization objects tooth and nail? Thanks, tglx From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Fri, 20 Oct 2017 08:34:36 +0200 (CEST) From: Thomas Gleixner To: Bart Van Assche cc: "mingo@kernel.org" , "peterz@infradead.org" , "byungchul.park@lge.com" , "linux-kernel@vger.kernel.org" , "amir73il@gmail.com" , "linux-block@vger.kernel.org" , "hch@infradead.org" , "linux-xfs@vger.kernel.org" , "linux-mm@kvack.org" , "oleg@redhat.com" , "darrick.wong@oracle.com" , "johannes.berg@intel.com" , "linux-fsdevel@vger.kernel.org" , "idryomov@gmail.com" , "tj@kernel.org" , "kernel-team@lge.com" , "david@fromorbit.com" Subject: Re: [RESEND PATCH 1/3] completion: Add support for initializing completion with lockdep_map In-Reply-To: <1508455438.4542.4.camel@wdc.com> Message-ID: References: <1508319532-24655-1-git-send-email-byungchul.park@lge.com> <1508319532-24655-2-git-send-email-byungchul.park@lge.com> <1508455438.4542.4.camel@wdc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: On Thu, 19 Oct 2017, Bart Van Assche wrote: > On Wed, 2017-10-18 at 18:38 +0900, Byungchul Park wrote: > > Sometimes, we want to initialize completions with sparate lockdep maps > > to assign lock classes under control. For example, the workqueue code > > manages lockdep maps, as it can classify lockdep maps properly. > > Provided a function for that purpose. > > > > Signed-off-by: Byungchul Park > > --- > > include/linux/completion.h | 8 ++++++++ > > 1 file changed, 8 insertions(+) > > > > diff --git a/include/linux/completion.h b/include/linux/completion.h > > index cae5400..182d56e 100644 > > --- a/include/linux/completion.h > > +++ b/include/linux/completion.h > > @@ -49,6 +49,13 @@ static inline void complete_release_commit(struct completion *x) > > lock_commit_crosslock((struct lockdep_map *)&x->map); > > } > > > > +#define init_completion_with_map(x, m) \ > > +do { \ > > + lockdep_init_map_crosslock((struct lockdep_map *)&(x)->map, \ > > + (m)->name, (m)->key, 0); \ > > + __init_completion(x); \ > > +} while (0) > > Are there any completion objects for which the cross-release checking is > useful? All of them by definition. > Are there any wait_for_completion() callers that hold a mutex or > other locking object? Yes, there are also cross completion dependencies. There have been such bugs and I expect more to be unearthed. I really have to ask what your motiviation is to fight the lockdep coverage of synchronization objects tooth and nail? Thanks, tglx -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org