From: Cornelia Huck <cohuck@redhat.com>
To: Halil Pasic <pasic@linux.ibm.com>
Cc: linux-s390@vger.kernel.org, Eric Farman <farman@linux.ibm.com>,
Alex Williamson <alex.williamson@redhat.com>,
Pierre Morel <pmorel@linux.ibm.com>,
kvm@vger.kernel.org, Farhan Ali <alifm@linux.ibm.com>,
qemu-devel@nongnu.org, qemu-s390x@nongnu.org
Subject: Re: [PATCH v3 1/6] vfio-ccw: make it safe to access channel programs
Date: Thu, 31 Jan 2019 12:52:20 +0100 [thread overview]
Message-ID: <20190131125220.285a4bc8.cohuck@redhat.com> (raw)
In-Reply-To: <20190130195127.5ff3c849@oc2783563651>
On Wed, 30 Jan 2019 19:51:27 +0100
Halil Pasic <pasic@linux.ibm.com> wrote:
> On Wed, 30 Jan 2019 14:22:07 +0100
> Cornelia Huck <cohuck@redhat.com> wrote:
>
> > When we get a solicited interrupt, the start function may have
> > been cleared by a csch, but we still have a channel program
> > structure allocated. Make it safe to call the cp accessors in
> > any case, so we can call them unconditionally.
>
> I read this like it is supposed to be safe regardless of
> parallelism and threads. However I don't see any explicit
> synchronization done for cp->initialized.
>
> I've managed to figure out how is that supposed to be safe
> for the cp_free() (which is probably our main concern) in
> vfio_ccw_sch_io_todo(), but if fail when it comes to the one
> in vfio_ccw_mdev_notifier().
>
> Can you explain us how does the synchronization work?
You read that wrong, I don't add synchronization, I just add a check.
WARNING: multiple messages have this Message-ID (diff)
From: Cornelia Huck <cohuck@redhat.com>
To: Halil Pasic <pasic@linux.ibm.com>
Cc: Eric Farman <farman@linux.ibm.com>,
Farhan Ali <alifm@linux.ibm.com>,
Pierre Morel <pmorel@linux.ibm.com>,
linux-s390@vger.kernel.org, kvm@vger.kernel.org,
qemu-devel@nongnu.org, qemu-s390x@nongnu.org,
Alex Williamson <alex.williamson@redhat.com>
Subject: Re: [Qemu-devel] [PATCH v3 1/6] vfio-ccw: make it safe to access channel programs
Date: Thu, 31 Jan 2019 12:52:20 +0100 [thread overview]
Message-ID: <20190131125220.285a4bc8.cohuck@redhat.com> (raw)
In-Reply-To: <20190130195127.5ff3c849@oc2783563651>
On Wed, 30 Jan 2019 19:51:27 +0100
Halil Pasic <pasic@linux.ibm.com> wrote:
> On Wed, 30 Jan 2019 14:22:07 +0100
> Cornelia Huck <cohuck@redhat.com> wrote:
>
> > When we get a solicited interrupt, the start function may have
> > been cleared by a csch, but we still have a channel program
> > structure allocated. Make it safe to call the cp accessors in
> > any case, so we can call them unconditionally.
>
> I read this like it is supposed to be safe regardless of
> parallelism and threads. However I don't see any explicit
> synchronization done for cp->initialized.
>
> I've managed to figure out how is that supposed to be safe
> for the cp_free() (which is probably our main concern) in
> vfio_ccw_sch_io_todo(), but if fail when it comes to the one
> in vfio_ccw_mdev_notifier().
>
> Can you explain us how does the synchronization work?
You read that wrong, I don't add synchronization, I just add a check.
next prev parent reply other threads:[~2019-01-31 11:52 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-30 13:22 [PATCH v3 0/6] vfio-ccw: support hsch/csch (kernel part) Cornelia Huck
2019-01-30 13:22 ` [Qemu-devel] " Cornelia Huck
2019-01-30 13:22 ` [PATCH v3 1/6] vfio-ccw: make it safe to access channel programs Cornelia Huck
2019-01-30 13:22 ` [Qemu-devel] " Cornelia Huck
2019-01-30 18:51 ` Halil Pasic
2019-01-30 18:51 ` [Qemu-devel] " Halil Pasic
2019-01-31 11:52 ` Cornelia Huck [this message]
2019-01-31 11:52 ` Cornelia Huck
2019-01-31 12:34 ` Halil Pasic
2019-01-31 12:34 ` [Qemu-devel] " Halil Pasic
2019-02-04 15:31 ` Cornelia Huck
2019-02-04 15:31 ` [Qemu-devel] " Cornelia Huck
2019-02-05 11:52 ` Halil Pasic
2019-02-05 11:52 ` [Qemu-devel] " Halil Pasic
2019-02-05 12:35 ` Cornelia Huck
2019-02-05 12:35 ` [Qemu-devel] " Cornelia Huck
2019-02-05 14:48 ` Eric Farman
2019-02-05 14:48 ` [Qemu-devel] " Eric Farman
2019-02-05 15:14 ` Farhan Ali
2019-02-05 15:14 ` [Qemu-devel] " Farhan Ali
2019-02-05 16:13 ` Cornelia Huck
2019-02-05 16:13 ` [Qemu-devel] " Cornelia Huck
2019-02-04 19:25 ` Eric Farman
2019-02-04 19:25 ` [Qemu-devel] " Eric Farman
2019-02-05 12:03 ` Cornelia Huck
2019-02-05 12:03 ` [Qemu-devel] " Cornelia Huck
2019-02-05 14:41 ` Eric Farman
2019-02-05 14:41 ` [Qemu-devel] " Eric Farman
2019-02-05 16:29 ` Cornelia Huck
2019-02-05 16:29 ` [Qemu-devel] " Cornelia Huck
2019-01-30 13:22 ` [PATCH v3 2/6] vfio-ccw: rework ssch state handling Cornelia Huck
2019-01-30 13:22 ` [Qemu-devel] " Cornelia Huck
2019-02-04 21:29 ` Eric Farman
2019-02-04 21:29 ` [Qemu-devel] " Eric Farman
2019-02-05 12:10 ` Cornelia Huck
2019-02-05 12:10 ` [Qemu-devel] " Cornelia Huck
2019-02-05 14:31 ` Eric Farman
2019-02-05 14:31 ` [Qemu-devel] " Eric Farman
2019-02-05 16:32 ` Cornelia Huck
2019-02-05 16:32 ` [Qemu-devel] " Cornelia Huck
2019-01-30 13:22 ` [PATCH v3 3/6] vfio-ccw: protect the I/O region Cornelia Huck
2019-01-30 13:22 ` [Qemu-devel] " Cornelia Huck
2019-02-08 21:26 ` Eric Farman
2019-02-08 21:26 ` [Qemu-devel] " Eric Farman
2019-02-11 15:57 ` Cornelia Huck
2019-02-11 15:57 ` [Qemu-devel] " Cornelia Huck
2019-01-30 13:22 ` [PATCH v3 4/6] vfio-ccw: add capabilities chain Cornelia Huck
2019-01-30 13:22 ` [Qemu-devel] " Cornelia Huck
2019-02-15 15:46 ` Eric Farman
2019-02-15 15:46 ` [Qemu-devel] " Eric Farman
2019-02-19 11:06 ` Cornelia Huck
2019-02-19 11:06 ` [Qemu-devel] " Cornelia Huck
2019-01-30 13:22 ` [PATCH v3 5/6] s390/cio: export hsch to modules Cornelia Huck
2019-01-30 13:22 ` [Qemu-devel] " Cornelia Huck
2019-01-30 13:22 ` [PATCH v3 6/6] vfio-ccw: add handling for async channel instructions Cornelia Huck
2019-01-30 13:22 ` [Qemu-devel] " Cornelia Huck
2019-01-30 17:00 ` Halil Pasic
2019-01-30 17:00 ` [Qemu-devel] " Halil Pasic
2019-01-30 17:09 ` Halil Pasic
2019-01-30 17:09 ` [Qemu-devel] " Halil Pasic
2019-01-31 11:53 ` Cornelia Huck
2019-01-31 11:53 ` [Qemu-devel] " Cornelia Huck
2019-02-06 14:00 ` [PATCH v3 0/6] vfio-ccw: support hsch/csch (kernel part) Cornelia Huck
2019-02-06 14:00 ` [Qemu-devel] " Cornelia Huck
2019-02-08 21:19 ` Eric Farman
2019-02-08 21:19 ` [Qemu-devel] " Eric Farman
2019-02-11 16:13 ` Cornelia Huck
2019-02-11 16:13 ` [Qemu-devel] " Cornelia Huck
2019-02-11 17:37 ` Eric Farman
2019-02-11 17:37 ` [Qemu-devel] " Eric Farman
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