From: "stern@rowland.harvard.edu" <stern@rowland.harvard.edu>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "Sverdlin,
Alexander \(Nokia - DE/Ulm\)" <alexander.sverdlin@nokia.com>,
"dinghao.liu@zju.edu.cn" <dinghao.liu@zju.edu.cn>,
"kjlu@umn.edu" <kjlu@umn.edu>,
"mpm@selenic.com" <mpm@selenic.com>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
"ben.dooks@codethink.co.uk" <ben.dooks@codethink.co.uk>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"arnd@arndb.de" <arnd@arndb.de>,
"allison@lohutok.net" <allison@lohutok.net>,
"yuehaibing@huawei.com" <yuehaibing@huawei.com>,
"rfontana@redhat.com" <rfontana@redhat.com>,
"linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Subject: Re: [PATCH] hwrng: ks-sa - fix runtime pm imbalance on error
Date: Thu, 28 May 2020 11:39:14 -0400 [thread overview]
Message-ID: <20200528153914.GA11831@rowland.harvard.edu> (raw)
In-Reply-To: <20200528065519.GA26960@gondor.apana.org.au>
On Thu, May 28, 2020 at 04:55:19PM +1000, Herbert Xu wrote:
> On Wed, May 20, 2020 at 12:45:56PM -0400, stern@rowland.harvard.edu wrote:
> > On Wed, May 20, 2020 at 03:42:17PM +0000, Sverdlin, Alexander (Nokia - DE/Ulm) wrote:
> > > Hello Dinghao,
> > >
> > > On Wed, 2020-05-20 at 21:29 +0800, Dinghao Liu wrote:
> > > > pm_runtime_get_sync() increments the runtime PM usage counter even
> > > > the call returns an error code. Thus a pairing decrement is needed
> > > > on the error handling path to keep the counter balanced.
> > >
> > > I believe, this is the wrong place for such kind of fix.
> > > pm_runtime_get_sync() has obviously a broken semantics with regards to
> > > your observation but no other driver does what you propose.
> >
> > Look again. For example, see what usb_autoresume_device() in
> > drivers/usb/core/driver.c does.
>
> However, there seems to be some disagreement as to what to do
> when pm_runtime_get_sync fails. Your driver chooses to call
> put_sync while others prefer pm_runtime_put_noidle (e.g., see
> drivers/base/power/runtime.c).
It doesn't matter which function gets called; in these circumstances
(device still suspended or in an error state because a resume attempt
failed) they will do the same thing.
> This API does seem to be in a bit of a mess.
Suggestions and patches are welcome.
Alan Stern
next prev parent reply other threads:[~2020-05-28 15:39 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-20 13:29 [PATCH] hwrng: ks-sa - fix runtime pm imbalance on error Dinghao Liu
2020-05-20 15:42 ` Sverdlin, Alexander (Nokia - DE/Ulm)
2020-05-20 16:45 ` stern
2020-05-28 6:55 ` Herbert Xu
2020-05-28 7:13 ` dinghao.liu
2020-05-28 15:39 ` stern [this message]
2020-05-21 6:21 ` dinghao.liu
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