Re: [Qemu-devel] [PATCH 2/2] ide/atapi: partially avoid deadlock if the storage backend is dead

2015-09-07 Thread Stefan Hajnoczi
On Sun, Sep 06, 2015 at 11:24:10AM +0200, Peter Lieven wrote: > > Taking a step back, what are the semantics of writing !(val & > > BM_CMD_START)? Is the device guaranteed to cancel/complete requests > > during the register write? > > I have to check that. John, do you have an idea? > > Stefan,

Re: [Qemu-devel] [PATCH 2/2] ide/atapi: partially avoid deadlock if the storage backend is dead

2015-09-07 Thread Peter Lieven
Am 07.09.2015 um 15:43 schrieb Stefan Hajnoczi: > On Sun, Sep 06, 2015 at 11:24:10AM +0200, Peter Lieven wrote: >>> Taking a step back, what are the semantics of writing !(val & >>> BM_CMD_START)? Is the device guaranteed to cancel/complete requests >>> during the register write? >> I have to

Re: [Qemu-devel] [PATCH 2/2] ide/atapi: partially avoid deadlock if the storage backend is dead

2015-09-06 Thread Peter Lieven
Am 03.09.2015 um 18:59 schrieb Stefan Hajnoczi: > On Thu, Aug 20, 2015 at 10:14:08AM +0200, Peter Lieven wrote: >> the blk_drain_all() that is executed if the guest issues a DMA cancel >> leads to a stuck main loop if the storage backend (e.g. a NFS share) >> is unresponsive. >> >> This scenario

Re: [Qemu-devel] [PATCH 2/2] ide/atapi: partially avoid deadlock if the storage backend is dead

2015-09-03 Thread Stefan Hajnoczi
On Thu, Aug 20, 2015 at 10:14:08AM +0200, Peter Lieven wrote: > the blk_drain_all() that is executed if the guest issues a DMA cancel > leads to a stuck main loop if the storage backend (e.g. a NFS share) > is unresponsive. > > This scenario is a common case for CDROM images mounted from an > NFS

Re: [Qemu-devel] [PATCH 2/2] ide/atapi: partially avoid deadlock if the storage backend is dead

2015-08-21 Thread Eric Blake
On 08/20/2015 01:14 AM, Peter Lieven wrote: the blk_drain_all() that is executed if the guest issues a DMA cancel leads to a stuck main loop if the storage backend (e.g. a NFS share) is unresponsive. This scenario is a common case for CDROM images mounted from an NFS share. In this case a

[Qemu-devel] [PATCH 2/2] ide/atapi: partially avoid deadlock if the storage backend is dead

2015-08-20 Thread Peter Lieven
the blk_drain_all() that is executed if the guest issues a DMA cancel leads to a stuck main loop if the storage backend (e.g. a NFS share) is unresponsive. This scenario is a common case for CDROM images mounted from an NFS share. In this case a broken NFS server can take down the whole VM even