[3.13.y.z extended stable] Patch "drm/vmwgfx: Fix a potential infinite spin waiting for fifo idle" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    drm/vmwgfx: Fix a potential infinite spin waiting for fifo idle

to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11.8.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 305b6691b357d8af235eec9377efb15d010c8267 Mon Sep 17 00:00:00 2001
From: Thomas Hellstrom <thellstrom at vmware.com>
Date: Thu, 28 Aug 2014 11:53:23 +0200
Subject: drm/vmwgfx: Fix a potential infinite spin waiting for fifo idle

commit f01ea0c3d9db536c64d47922716d8b3b8f21d850 upstream.

The code waiting for fifo idle was incorrect and could possibly spin
forever under certain circumstances.

Signed-off-by: Thomas Hellstrom <thellstrom at vmware.com>
Reported-by: Mark Sheldon <markshel at vmware.com>
Reviewed-by: Jakob Bornecrantz <jakob at vmware.com>
Reivewed-by: Mark Sheldon <markshel at vmware.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c b/drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c
index 3eb1486..8966493 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c
@@ -163,8 +163,9 @@ void vmw_fifo_release(struct vmw_private *dev_priv, struct vmw_fifo_state *fifo)

 	mutex_lock(&dev_priv->hw_mutex);

+	vmw_write(dev_priv, SVGA_REG_SYNC, SVGA_SYNC_GENERIC);
 	while (vmw_read(dev_priv, SVGA_REG_BUSY) != 0)
-		vmw_write(dev_priv, SVGA_REG_SYNC, SVGA_SYNC_GENERIC);
+		;

 	dev_priv->last_read_seqno = ioread32(fifo_mem + SVGA_FIFO_FENCE);

--
1.9.1