From: "Verma, Vishal L" <vishal.l.verma@intel.com>
To: "akpm@linux-foundation.org" <akpm@linux-foundation.org>
Cc: "Williams, Dan J" <dan.j.williams@intel.com>,
"Jiang, Dave" <dave.jiang@intel.com>,
"Schofield, Alison" <alison.schofield@intel.com>,
"nvdimm@lists.linux.dev" <nvdimm@lists.linux.dev>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-cxl@vger.kernel.org" <linux-cxl@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] dax/bus.c: replace WARN_ON_ONCE() with lockdep asserts
Date: Thu, 4 Apr 2024 21:32:24 +0000 [thread overview]
Message-ID: <556a9d595b815ac459f1d43f5b6394b41f661e60.camel@intel.com> (raw)
In-Reply-To: <20240404142326.b3d5b0f3f7b9f25f1a16288a@linux-foundation.org>
On Thu, 2024-04-04 at 14:23 -0700, Andrew Morton wrote:
> On Tue, 02 Apr 2024 00:24:28 -0600 Vishal Verma <vishal.l.verma@intel.com> wrote:
>
> > In [1], Dan points out that all of the WARN_ON_ONCE() usage in the
> > referenced patch should be replaced with lockdep_assert_held(_write)().
> >
> > Replace those, and additionally, replace a couple of other
> > WARN_ON_ONCE() introduced in the same patch for actual failure
> > cases (i.e. when acquiring a semaphore fails in a remove / unregister
> > path) with dev_WARN_ONCE() as is the precedent here.
> >
> > Recall that previously, unregistration paths was implicitly protected by
> > overloading the device lock, which the patch in [1] sought to remove.
> > This meant adding a semaphore acquisition in these unregistration paths.
> > Since that can fail, and it doesn't make sense to return errors from
> > these paths, retain the two instances of (now) dev_WARN_ONCE().
> >
> > ...
> >
> > @@ -471,6 +471,7 @@ static void __unregister_dev_dax(void *dev)
> >
> > dev_dbg(dev, "%s\n", __func__);
> >
> > + lockdep_assert_held_write(&dax_region_rwsem);
> > kill_dev_dax(dev_dax);
> > device_del(dev);
> > free_dev_dax_ranges(dev_dax);
>
> This is new and unchangelogged?
>
> I'm taking Dan's reply to your patch as Not-A-Nack ;)
>
True, but with Dan's new feedback, that results in a bit more rework,
this will likely turn into 2-3 patches. Working on it now, will be out
shortly!
prev parent reply other threads:[~2024-04-04 21:33 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-02 6:24 [PATCH] dax/bus.c: replace WARN_ON_ONCE() with lockdep asserts Vishal Verma
2024-04-04 2:33 ` Dan Williams
2024-04-04 21:23 ` Andrew Morton
2024-04-04 21:32 ` Verma, Vishal L [this message]
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