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Re: [Qemu-devel] [PATCH v2 1/3] xenfb: use the correct condition to avoi
From: |
Stefano Stabellini |
Subject: |
Re: [Qemu-devel] [PATCH v2 1/3] xenfb: use the correct condition to avoid excessive looping |
Date: |
Tue, 12 Apr 2016 10:12:28 -0700 (PDT) |
User-agent: |
Alpine 2.10 (DEB 1266 2009-07-14) |
On Tue, 12 Apr 2016, Wei Liu wrote:
> In commit ac0487e1 ("xenfb.c: avoid expensive loops when prod <=
> out_cons"), ">=" was used. In fact, a full ring is a legit state.
> Correct the test to use ">".
>
> Reported-by: "Hao, Xudong" <address@hidden>
> Signed-off-by: Wei Liu <address@hidden>
> Tested-by: "Hao, Xudong" <address@hidden>
> Acked-by: Anthony Perard <address@hidden>
Acked-by: Stefano Stabellini <address@hidden>
I'll add it to my queue
> Cc: Stefano Stabellini <address@hidden>
> Cc: Anthony Perard <address@hidden>
>
> Backport candidate to our own tree.
> ---
> 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 */
> --
> 2.1.4
>