* [Qemu-devel] [PATCH] xenfb: Fix overzealous ring test
@ 2016-04-18 12:41 Samuel Thibault
2016-04-18 14:40 ` Wei Liu
0 siblings, 1 reply; 3+ messages in thread
From: Samuel Thibault @ 2016-04-18 12:41 UTC (permalink / raw)
To: qemu-devel
Cc: Wei Liu, Stefano Stabellini, Anthony Perard, xen-devel,
Samuel Thibault
From: Wei Liu <wei.liu2@citrix.com>
pv-grub booting got broken with recent qemu-xen, due to
ac0487e1d2ae811cd4d035741a109a4ecfb013f1 ('xenfb.c: avoid expensive loops
when prod <= out_cons')
prod - out_cons can actually be XENFB_OUT_RING_LEN when the ring is exactly
full, this is a normal condition and should not be excluded.
From: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Tested-by: Hao Xudong <xudong.hao@intel.com>
---
hw/display/xenfb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/hw/display/xenfb.c b/hw/display/xenfb.c
index 40b096a..9866dfd 100644
--- a/hw/display/xenfb.c
+++ b/hw/display/xenfb.c
@@ -775,7 +775,7 @@ static void xenfb_handle_events(struct XenFB *xenfb)
prod = page->out_prod;
out_cons = page->out_cons;
- if (prod - out_cons >= XENFB_OUT_RING_LEN) {
+ if (prod - out_cons > XENFB_OUT_RING_LEN) {
return;
}
xen_rmb(); /* ensure we see ring contents up to prod */
--
2.8.0.rc3
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [Qemu-devel] [PATCH] xenfb: Fix overzealous ring test
2016-04-18 12:41 [Qemu-devel] [PATCH] xenfb: Fix overzealous ring test Samuel Thibault
@ 2016-04-18 14:40 ` Wei Liu
2016-04-18 14:54 ` Samuel Thibault
0 siblings, 1 reply; 3+ messages in thread
From: Wei Liu @ 2016-04-18 14:40 UTC (permalink / raw)
To: Samuel Thibault
Cc: qemu-devel, Wei Liu, Stefano Stabellini, Anthony Perard,
xen-devel
On Mon, Apr 18, 2016 at 02:41:48PM +0200, Samuel Thibault wrote:
> From: Wei Liu <wei.liu2@citrix.com>
>
> pv-grub booting got broken with recent qemu-xen, due to
> ac0487e1d2ae811cd4d035741a109a4ecfb013f1 ('xenfb.c: avoid expensive loops
> when prod <= out_cons')
>
> prod - out_cons can actually be XENFB_OUT_RING_LEN when the ring is exactly
> full, this is a normal condition and should not be excluded.
>
> From: Wei Liu <wei.liu2@citrix.com>
> Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
> Tested-by: Hao Xudong <xudong.hao@intel.com>
Hi Samuel,
This patch is already queued by Stefano. After it has been applied
upstream we will backport it to our own tree.
Wei.
> ---
> hw/display/xenfb.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/display/xenfb.c b/hw/display/xenfb.c
> index 40b096a..9866dfd 100644
> --- a/hw/display/xenfb.c
> +++ b/hw/display/xenfb.c
> @@ -775,7 +775,7 @@ static void xenfb_handle_events(struct XenFB *xenfb)
>
> prod = page->out_prod;
> out_cons = page->out_cons;
> - if (prod - out_cons >= XENFB_OUT_RING_LEN) {
> + if (prod - out_cons > XENFB_OUT_RING_LEN) {
> return;
> }
> xen_rmb(); /* ensure we see ring contents up to prod */
> --
> 2.8.0.rc3
>
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2016-04-18 14:54 UTC | newest]
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2016-04-18 14:40 ` Wei Liu
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