Linux Virtualization - Oct 2014 - [3.16 stable PATCH 0/2] virtio-rng: two backports to fix stuck

I received two mails about faile to apply patches to 3.16-stable tree:

FAILED: patch "[PATCH] virtio-rng: skip reading when we start to remove the
device" failed to apply to 3.16-stable tree
FAILED: patch "[PATCH] virtio-rng: fix stuck of hot-unplugging busy
device" failed to apply to 3.16-stable tree

Amit already backported two patches for 3.16-stable, then cherry-pick
of my two patches works.

Thanks.

Amos Kong (2):
  virtio-rng: fix stuck of hot-unplugging busy device
  virtio-rng: skip reading when we start to remove the device

 drivers/char/hw_random/virtio-rng.c | 7 +++++++
 1 file changed, 7 insertions(+)

-- 
1.9.3

When we try to hot-remove a busy virtio-rng device from QEMU monitor,
the device can't be hot-removed. Because virtio-rng driver hangs at
wait_for_completion_killable().

This patch exits the waiting by completing have_data completion before
unregistering, resets data_avail to avoid the hwrng core use wrong
buffer bytes.

Signed-off-by: Amos Kong <akong at redhat.com>
Reviewed-by: Amit Shah <amit.shah at redhat.com>
Cc: stable at vger.kernel.org
Signed-off-by: Rusty Russell <rusty at rustcorp.com.au>
(cherry picked from commit 3856e548372513665670ca5db60d9a74b970fe0d)
Signed-off-by: Amos Kong <akong at redhat.com>
---
 drivers/char/hw_random/virtio-rng.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/char/hw_random/virtio-rng.c
b/drivers/char/hw_random/virtio-rng.c
index f1aa13b..b50252c 100644
--- a/drivers/char/hw_random/virtio-rng.c
+++ b/drivers/char/hw_random/virtio-rng.c
@@ -137,6 +137,8 @@ static void remove_common(struct virtio_device *vdev)
 {
 	struct virtrng_info *vi = vdev->priv;
 
+	vi->data_avail = 0;
+	complete(&vi->have_data);
 	vdev->config->reset(vdev);
 	vi->busy = false;
 	if (vi->hwrng_register_done)
-- 
1.9.3

Before we really unregister the hwrng device, reading will get stuck if
the virtio device is reset. We should return error for reading when we
start to remove the device.

Signed-off-by: Amos Kong <akong at redhat.com>
Reviewed-by: Amit Shah <amit.shah at redhat.com>
Cc: stable at vger.kernel.org
Signed-off-by: Rusty Russell <rusty at rustcorp.com.au>
(cherry picked from commit f49819560f53b7f3a596a8ea2e6764dc86695b62)
Signed-off-by: Amos Kong <akong at redhat.com>
---
 drivers/char/hw_random/virtio-rng.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/char/hw_random/virtio-rng.c
b/drivers/char/hw_random/virtio-rng.c
index b50252c..cb1688a 100644
--- a/drivers/char/hw_random/virtio-rng.c
+++ b/drivers/char/hw_random/virtio-rng.c
@@ -37,6 +37,7 @@ struct virtrng_info {
 	char name[25];
 	int index;
 	bool hwrng_register_done;
+	bool hwrng_removed;
 };
 
 
@@ -69,6 +70,9 @@ static int virtio_read(struct hwrng *rng, void *buf, size_t
size, bool wait)
 	int ret;
 	struct virtrng_info *vi = (struct virtrng_info *)rng->priv;
 
+	if (vi->hwrng_removed)
+		return -ENODEV;
+
 	if (!vi->busy) {
 		vi->busy = true;
 		init_completion(&vi->have_data);
@@ -137,6 +141,7 @@ static void remove_common(struct virtio_device *vdev)
 {
 	struct virtrng_info *vi = vdev->priv;
 
+	vi->hwrng_removed = true;
 	vi->data_avail = 0;
 	complete(&vi->have_data);
 	vdev->config->reset(vdev);
-- 
1.9.3

On Sat, Oct 11, 2014 at 06:51:47AM +0800, Amos Kong
wrote:
> I received two mails about faile to apply patches to 3.16-stable tree:
> 
> FAILED: patch "[PATCH] virtio-rng: skip reading when we start to
remove the device" failed to apply to 3.16-stable tree
> FAILED: patch "[PATCH] virtio-rng: fix stuck of hot-unplugging busy
device" failed to apply to 3.16-stable tree
> 
> Amit already backported two patches for 3.16-stable, then cherry-pick
> of my two patches works.
> 
> Thanks.
Ping Greg, thanks.
 
> Amos Kong (2):
>   virtio-rng: fix stuck of hot-unplugging busy device
>   virtio-rng: skip reading when we start to remove the device
> 
>  drivers/char/hw_random/virtio-rng.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> -- 
> 1.9.3
> 
> --
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> Please read the FAQ at  http://www.tux.org/lkml/
-- 
			Amos.

Hi Amos

On Tue, Nov 04, 2014 at 12:32:27PM +0800, Amos Kong
wrote:
> On Sat, Oct 11, 2014 at 06:51:47AM +0800, Amos Kong wrote:
> > I received two mails about faile to apply patches to 3.16-stable tree:
> > 
> > FAILED: patch "[PATCH] virtio-rng: skip reading when we start to
remove the device" failed to apply to 3.16-stable tree
> > FAILED: patch "[PATCH] virtio-rng: fix stuck of hot-unplugging
busy device" failed to apply to 3.16-stable tree
> > 
> > Amit already backported two patches for 3.16-stable, then cherry-pick
> > of my two patches works.
> > 
> > Thanks.
> 
> Ping Greg, thanks.
>  
I'm now doing the extended stable maintenance of the 3.16 kernel, as
Greg has EOL'ed it.

Anyway, I will be queuing these 2 patches for the extended 3.16
kernel.  Thank you!

Cheers,
--
Lu?s
> > Amos Kong (2):
> >   virtio-rng: fix stuck of hot-unplugging busy device
> >   virtio-rng: skip reading when we start to remove the device
> > 
> >  drivers/char/hw_random/virtio-rng.c | 7 +++++++
> >  1 file changed, 7 insertions(+)
> > 
> > -- 
> > 1.9.3
> > 
> > --
> > To unsubscribe from this list: send the line "unsubscribe
linux-kernel" in
> > the body of a message to majordomo at vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at  http://www.tux.org/lkml/
> 
> -- 
> 			Amos.
> --
> To unsubscribe from this list: send the line "unsubscribe stable"
in
> the body of a message to majordomo at vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

On Tue, Nov 04, 2014 at 12:32:27PM +0800, Amos Kong
wrote:
> On Sat, Oct 11, 2014 at 06:51:47AM +0800, Amos Kong wrote:
> > I received two mails about faile to apply patches to 3.16-stable tree:
> > 
> > FAILED: patch "[PATCH] virtio-rng: skip reading when we start to
remove the device" failed to apply to 3.16-stable tree
> > FAILED: patch "[PATCH] virtio-rng: fix stuck of hot-unplugging
busy device" failed to apply to 3.16-stable tree
> > 
> > Amit already backported two patches for 3.16-stable, then cherry-pick
> > of my two patches works.
> > 
> > Thanks.
> 
> Ping Greg, thanks.
Why me?  3.16-stable is end-of-life, I'm no longer maintaining it, so
what can I do here with these patches?

confused,

greg k-h