From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: [PATCHv7 0/2] Xen: FIFO-based event channel fixes Date: Tue, 10 Dec 2013 13:56:58 +0000 Message-ID: <1386683820-9834-1-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: Keir Fraser , David Vrabel , Jan Beulich List-Id: xen-devel@lists.xenproject.org This series fixes two bugs in the FIFO-based event channel ABI. With the first bug, the priority of a newly bound event may not be the default (it might have been an old priority for that port or 0). The second bug is triggered by moving events between queues (either moving VCPUs or changing their priority). This would cause events to be lost. 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 complete set of XenServer's automated regression tests and no issues were found. Changes in v7: - Add patch to initialize priority of all newly bound events. 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