From: Jason Gunthorpe <jgg@nvidia.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: linux-cxl@vger.kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Vishal L Verma <vishal.l.verma@intel.com>,
"Weiny, Ira" <ira.weiny@intel.com>,
"Schofield, Alison" <alison.schofield@intel.com>
Subject: Re: [PATCH v2 2/4] cxl/mem: Fix synchronization mechanism for device removal vs ioctl operations
Date: Tue, 30 Mar 2021 14:02:53 -0300 [thread overview]
Message-ID: <20210330170253.GU2356281@nvidia.com> (raw)
In-Reply-To: <CAPcyv4hL-B=1hostoj9t6EE5impmcDR2-wsgahvBKdzL9LbqLg@mail.gmail.com>
On Tue, Mar 30, 2021 at 09:05:29AM -0700, Dan Williams wrote:
> > If you can't clearly point to the *data* under RCU protection it is
> > being used wrong.
>
> Agree.
>
> The data being protected is the value of
> dev->kobj.state_in_sysfs. The
So where is that read under:
+ idx = srcu_read_lock(&cxl_memdev_srcu);
+ rc = __cxl_memdev_ioctl(cxlmd, cmd, arg);
+ srcu_read_unlock(&cxl_memdev_srcu, idx);
?
It can't read the RCU protected data outside the RCU critical region,
and it can't read/write RCU protected data without using the helper
macros which insert the required barriers.
IMHO this can't use 'dev->kobj.state_in_sysfs' as the RCU protected data.
Jason
next prev parent reply other threads:[~2021-03-30 17:04 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-30 2:47 [PATCH v2 0/4] cxl/mem: Fix memdev device setup Dan Williams
2021-03-30 2:47 ` [PATCH v2 1/4] cxl/mem: Use sysfs_emit() for attribute show routines Dan Williams
2021-03-30 2:47 ` [PATCH v2 2/4] cxl/mem: Fix synchronization mechanism for device removal vs ioctl operations Dan Williams
2021-03-30 11:16 ` Jason Gunthorpe
2021-03-30 15:37 ` Dan Williams
2021-03-30 15:47 ` Jason Gunthorpe
2021-03-30 16:05 ` Dan Williams
2021-03-30 17:02 ` Jason Gunthorpe [this message]
2021-03-30 17:31 ` Dan Williams
2021-03-30 17:54 ` Jason Gunthorpe
2021-03-30 19:00 ` Dan Williams
2021-03-30 19:26 ` Jason Gunthorpe
2021-03-30 19:43 ` Dan Williams
2021-03-30 19:51 ` Jason Gunthorpe
2021-03-30 21:00 ` Dan Williams
2021-03-30 22:09 ` Jason Gunthorpe
2021-03-30 2:47 ` [PATCH v2 3/4] cxl/mem: Do not rely on device_add() side effects for dev_set_name() failures Dan Williams
2021-03-30 2:48 ` [PATCH v2 4/4] cxl/mem: Disable cxl device power management Dan Williams
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