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Wong" , Vishal Verma , Dave Jiang , Alison Schofield , nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org Subject: Re: [PATCH v4 2/9] dax: use READ_ONCE() in dax_holder() Message-ID: References: <20261008112004.1899560-1-mszeredi@redhat.com> <20261008112004.1899560-3-mszeredi@redhat.com> Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261008112004.1899560-3-mszeredi@redhat.com> On Thu, Oct 08, 2026 at 01:19:53PM +0200, Miklos Szeredi wrote: > A future fuse patch will utilize dax_holder() in RCU context to make sure > that the holder can't be freed by a racing fs_put_dax. > > This patch just makes sure that dax_holder() works properly in such a > context by adding READ_ONCE() (equivalent to rcu_dereference minus sanity > checks). > > Signed-off-by: Miklos Szeredi Reviewed-by: Gregory Price (Meta) > --- > drivers/dax/super.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/dax/super.c b/drivers/dax/super.c > index 25836f389bde..76e8d3654629 100644 > --- a/drivers/dax/super.c > +++ b/drivers/dax/super.c > @@ -642,7 +642,7 @@ EXPORT_SYMBOL_GPL(put_dax); > */ > void *dax_holder(struct dax_device *dax_dev) > { > - return dax_dev->holder_data; > + return READ_ONCE(dax_dev->holder_data); > } > EXPORT_SYMBOL_GPL(dax_holder); > > -- > 2.54.0 >