From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: [PATCHv6 0/1] Xen: FIFO-based event channel fix Date: Fri, 6 Dec 2013 17:38:31 +0000 Message-ID: <1386351512-16388-1-git-send-email-david.vrabel@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: xen-devel@lists.xen.org Cc: David Vrabel , Jan Beulich List-Id: xen-devel@lists.xenproject.org This fixes a bug triggered by moving events between queues (either moving VCPUs or changing their priority). Testing with a process continually moving all event channels between VCPUs has been done. This would previously fail in under an hour but with this fix the system stayed up for over 10 days. It has also been through a reduced set of XenServer's automated tests and no issues were found. I would have preferred to run though the full set of tests but it didn't look like I'd get a slot before the first 4.4 release candidate. Changes in v6: - Limit loop to acquire old_q->lock to 3 iterations. Changes in v5: - Only set READY bits for new heads. - Rework old tail bug fix to cover all cases. Changes in v4: - const struct domain * - Clear BUSY with existing cmpxchg() where possible. - Fix BUSY bit debug output. Changes in v3: - Use a new BUSY bit to block guests from clearing UNMASKED, this is lower overhead than the previous solution (which required a hypercall). - Fix another problem with moving events between queues. - Add evtchn->last_vpcu_id and evtchn->last_priority instead of evtchn->q. This keeps the structure at 32 bytes long. Changes in v2: - Add MAINTAINERS patch - Remove some unnecessary temporary pending state clears - Add fix for DoS David