From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: "Brown, Len" <len.brown@intel.com>,
bvanassche@acm.org, linux-nvdimm <linux-nvdimm@lists.01.org>,
Greg KH <gregkh@linuxfoundation.org>,
Linux-pm mailing list <linux-pm@vger.kernel.org>,
jiangshanlai@gmail.com,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"Luis R. Rodriguez" <mcgrof@kernel.org>,
Pavel Machek <pavel@ucw.cz>,
zwisler@kernel.org, Tejun Heo <tj@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
"Rafael J. Wysocki" <rafael@kernel.org>
Subject: Re: [driver-core PATCH v8 2/9] driver core: Establish order of operations for device_add and device_del via bitflag
Date: Mon, 10 Dec 2018 14:24:10 -0800 [thread overview]
Message-ID: <00810f93b199c524378b5c963d49bd798c5d9843.camel@linux.intel.com> (raw)
In-Reply-To: <CAPcyv4hrML3SKnFP9UANC-hdTrpnOx4nWX=b-yhLsLuujL5oAA@mail.gmail.com>
On Mon, 2018-12-10 at 13:23 -0800, Dan Williams wrote:
> On Mon, Dec 10, 2018 at 1:15 PM Dan Williams <dan.j.williams@intel.com> wrote:
> >
> > On Mon, Dec 10, 2018 at 12:58 PM Alexander Duyck
> > <alexander.h.duyck@linux.intel.com> wrote:
>
> [..]
> > > Also the context for the two functions seems to be a bit different. In
> > > the case of __device_attach_driver the device_lock is already held. In
> > > __driver_attach the lock on the device isn't taken until after a match
> > > has been found.
> >
> > Yes, I was only pattern matching when looking at the context of where
> > dev->dead is checked in __driver_attach() and wondering why it was
> > checked outside of __device_attach_driver()
>
> ...and now I realize the bigger point of your concern, we need to
> check dev->dead after acquiring the device_lock otherwise the race is
> back. We can defer that consolidation, but the larger concern of
> making it internal to __device_attach_driver() still stands.
I'm still not a fan of moving it into __device_attach_driver. I would
much rather pull out the dev->driver check and instead place that in
__device_attach_async_helper.
The __device_attach function as I said took the device_lock and had
already checked dev->driver. So in the non-async path it shouldn't be
possible for dev->driver to ever be set anyway. In addition
__device_attach_driver is called once for each driver on a given bus,
so dropping the test should reduce driver load time since it is one
less test that has to be performed per driver.
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next prev parent reply other threads:[~2018-12-10 22:24 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-05 17:25 [driver-core PATCH v8 0/9] Add NUMA aware async_schedule calls Alexander Duyck
2018-12-05 17:25 ` [driver-core PATCH v8 1/9] driver core: Move async_synchronize_full call Alexander Duyck
2018-12-05 17:25 ` [driver-core PATCH v8 2/9] driver core: Establish order of operations for device_add and device_del via bitflag Alexander Duyck
2018-12-10 18:58 ` Dan Williams
2018-12-10 19:35 ` Alexander Duyck
2018-12-10 19:43 ` Dan Williams
2018-12-10 20:57 ` Alexander Duyck
2018-12-10 21:15 ` Dan Williams
2018-12-10 21:23 ` Dan Williams
2018-12-10 22:24 ` Alexander Duyck [this message]
2018-12-10 22:41 ` Dan Williams
2018-12-05 17:25 ` [driver-core PATCH v8 3/9] device core: Consolidate locking and unlocking of parent and device Alexander Duyck
2018-12-05 17:25 ` [driver-core PATCH v8 4/9] driver core: Probe devices asynchronously instead of the driver Alexander Duyck
2018-12-05 17:25 ` [driver-core PATCH v8 5/9] workqueue: Provide queue_work_node to queue work near a given NUMA node Alexander Duyck
2018-12-05 17:25 ` [driver-core PATCH v8 6/9] async: Add support for queueing on specific " Alexander Duyck
2018-12-05 17:25 ` [driver-core PATCH v8 7/9] driver core: Attach devices on CPU local to device node Alexander Duyck
2018-12-05 17:25 ` [driver-core PATCH v8 8/9] PM core: Use new async_schedule_dev command Alexander Duyck
2018-12-05 17:26 ` [driver-core PATCH v8 9/9] libnvdimm: Schedule device registration on node local to the device Alexander Duyck
2018-12-10 19:22 ` [driver-core PATCH v8 0/9] Add NUMA aware async_schedule calls Luis Chamberlain
2018-12-10 23:25 ` Alexander Duyck
2018-12-10 23:35 ` Luis Chamberlain
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