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h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=2ahsi3Z15c5odISV0SkywBPiGig9wTvX0Ka/UkXIVW+H/rOvFx2LjenR8JvmmJaVW x/G8ctfg3uXuIWCVHQR+RDiIob8i7L/jkYvZ9TE+oVm5lMsWZUv+uYgILI0fjzBbL5 biGDqji/jICTM+7jBY/fqSfO35D/rROcaFI/wuJE= Date: Fri, 15 Dec 2023 08:27:42 +0100 From: Greg Kroah-Hartman To: Vishal Verma Cc: Dan Williams , Dave Jiang , Andrew Morton , Oscar Salvador , linux-kernel@vger.kernel.org, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, David Hildenbrand , Dave Hansen , Huang Ying , linux-mm@kvack.org, Joao Martins Subject: Re: [PATCH v6 2/4] dax/bus: Use guard(device) in sysfs attribute helpers Message-ID: <2023121515-litigate-finished-76dd@gregkh> References: <20231214-vv-dax_abi-v6-0-ad900d698438@intel.com> <20231214-vv-dax_abi-v6-2-ad900d698438@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231214-vv-dax_abi-v6-2-ad900d698438@intel.com> X-Rspamd-Queue-Id: C7E3980002 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: q1aeruwrd956wn6r36uzkez3k5tyider X-HE-Tag: 1702625269-98670 X-HE-Meta: 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 C8sUJFfR SVjC8FzQBNuqkVabt2NwaS1NgplJHXzRVecJMAGysRvicHz/b7Gvr/PDGKkzVw+Knx5/BYXYD8YslbwL654/DaokTUvQxRSsEHVnct/9gFu69TUgG3oSdwafK39nUauIQWdNTaYSclqXiRuATRlWcj1bxib88OUm3xEJPNJ1r9KTrcne7OfK1KbWYEV7LFqnKJFXdIx1MivFd/5dB/OCF1T/vvHqV3/vyM6DIMsV1arL4LkKDFO/Y8rpaRHrhD30OwiJS9hYGufa1Imo= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Dec 14, 2023 at 10:25:27PM -0700, Vishal Verma wrote: > Use the guard(device) macro to lock a 'struct device', and unlock it > automatically when going out of scope using Scope Based Resource > Management semantics. A lot of the sysfs attribute writes in > drivers/dax/bus.c benefit from a cleanup using these, so change these > where applicable. Wait, why are you needing to call device_lock() at all here? Why is dax special in needing this when no other subsystem requires it? > > Cc: Joao Martins > Cc: Dan Williams > Signed-off-by: Vishal Verma > --- > drivers/dax/bus.c | 143 ++++++++++++++++++++++-------------------------------- > 1 file changed, 59 insertions(+), 84 deletions(-) > > diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c > index 1ff1ab5fa105..6226de131d17 100644 > --- a/drivers/dax/bus.c > +++ b/drivers/dax/bus.c > @@ -294,13 +294,10 @@ static ssize_t available_size_show(struct device *dev, > struct device_attribute *attr, char *buf) > { > struct dax_region *dax_region = dev_get_drvdata(dev); > - unsigned long long size; > > - device_lock(dev); > - size = dax_region_avail_size(dax_region); > - device_unlock(dev); > + guard(device)(dev); You have a valid device here, why are you locking it? How can it go away? And if it can, shouldn't you have a local lock for it, and not abuse the driver core lock? > > - return sprintf(buf, "%llu\n", size); > + return sprintf(buf, "%llu\n", dax_region_avail_size(dax_region)); sysfs_emit() everywhere please. But again, the issue is "why do you need a lock"? thanks, greg k-h