From: KY Srinivasan <kys@microsoft.com>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"devel@linuxdriverproject.org" <devel@linuxdriverproject.org>,
"olaf@aepfle.de" <olaf@aepfle.de>,
"apw@canonical.com" <apw@canonical.com>,
"vkuznets@redhat.com" <vkuznets@redhat.com>,
"jasowang@redhat.com" <jasowang@redhat.com>
Subject: RE: [PATCH 2/7] Drivers: hv: vmbus: Use READ_ONCE() to read variables that are volatile
Date: Fri, 1 Apr 2016 22:02:42 +0000 [thread overview]
Message-ID: <CY1PR03MB213792CD8EFCF66E6E61CA09A09A0@CY1PR03MB2137.namprd03.prod.outlook.com> (raw)
In-Reply-To: <20160401000049.GC10232@kroah.com>
> -----Original Message-----
> From: Greg KH [mailto:gregkh@linuxfoundation.org]
> Sent: Thursday, March 31, 2016 5:01 PM
> To: KY Srinivasan <kys@microsoft.com>
> Cc: linux-kernel@vger.kernel.org; devel@linuxdriverproject.org;
> olaf@aepfle.de; apw@canonical.com; vkuznets@redhat.com;
> jasowang@redhat.com
> Subject: Re: [PATCH 2/7] Drivers: hv: vmbus: Use READ_ONCE() to read
> variables that are volatile
>
> On Wed, Mar 23, 2016 at 05:53:52PM -0700, K. Y. Srinivasan wrote:
> > Use the READ_ONCE macro to access variabes that can change
> asynchronously.
>
> Why? What is this "fixing"?
This is to prevent the compiler optimizations and moving the code. This is the
recommended mechanism for reading volatile variables.
Regards,
K. Y
>
> thanks,
>
> greg k-h
next prev parent reply other threads:[~2016-04-01 22:02 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-24 0:53 [PATCH 0/7] Drivers: hv: vmbus: Cleanup the ring buffer code K. Y. Srinivasan
2016-03-24 0:53 ` [PATCH 1/7] Drivers: hv: vmbus: Introduce functions for estimating room in the ring buffer K. Y. Srinivasan
2016-03-24 0:53 ` [PATCH 2/7] Drivers: hv: vmbus: Use READ_ONCE() to read variables that are volatile K. Y. Srinivasan
2016-04-01 0:00 ` Greg KH
2016-04-01 22:02 ` KY Srinivasan [this message]
2016-03-24 0:53 ` [PATCH 3/7] Drivers: hv: vmbus: Fix a bug in hv_need_to_signal_on_read() K. Y. Srinivasan
2016-03-31 23:59 ` Greg KH
2016-04-01 21:03 ` KY Srinivasan
2016-04-01 0:00 ` Greg KH
2016-04-01 21:57 ` KY Srinivasan
2016-03-24 0:53 ` [PATCH 4/7] Drivers: hv: vmbus: Use the new virt_xx barrier code K. Y. Srinivasan
2016-03-24 0:53 ` [PATCH 5/7] Drivers: hv: vmbus: Export the vmbus_set_event() API K. Y. Srinivasan
2016-03-24 0:53 ` [PATCH 6/7] Drivers: hv: vmbus: Move some ring buffer functions to hyperv.h K. Y. Srinivasan
2016-03-24 0:53 ` [PATCH 7/7] Drivers: hv: vmbus: Implement APIs to support "in place" consumption of vmbus packets K. Y. Srinivasan
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