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From: Wei Liu <wei.liu2@citrix.com>
To: qemu-devel@nongnu.org
Cc: Anthony Perard <anthony.perard@citrix.com>,
	Xen-devel <xen-devel@lists.xenproject.org>,
	Stefano Stabellini <sstabellini@kernel.org>,
	Wei Liu <wei.liu2@citrix.com>
Subject: [PATCH v2 1/3] xenfb: use the correct condition to avoid excessive looping
Date: Tue, 12 Apr 2016 11:43:14 +0100	[thread overview]
Message-ID: <1460457796-1779-2-git-send-email-wei.liu2__32139.6198742606$1460457788$gmane$org@citrix.com> (raw)
In-Reply-To: <1460457796-1779-1-git-send-email-wei.liu2@citrix.com>

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" <xudong.hao@intel.com>
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Tested-by: "Hao, Xudong" <xudong.hao@intel.com>
Acked-by: Anthony Perard <anthony.perard@citrix.com>
---
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Anthony Perard <anthony.perard@citrix.com>

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


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  reply	other threads:[~2016-04-12 10:41 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-04-12 10:43 [PATCH v2 0/3] xenfb bug fixes and cleanup Wei Liu
2016-04-12 10:43 ` Wei Liu [this message]
2016-04-12 10:43 ` [PATCH v2 2/3] xenfb: move xen_rmb to the correct location Wei Liu
2016-04-12 12:57   ` David Vrabel
     [not found]   ` <570CF0B1.9070507@citrix.com>
2016-04-12 13:38     ` Andrew Cooper
     [not found]     ` <570CFA45.7070504@citrix.com>
2016-04-12 13:46       ` Wei Liu
     [not found]       ` <20160412134603.GC18652@citrix.com>
2016-04-12 17:31         ` Stefano Stabellini
2016-04-12 10:43 ` [PATCH v2 3/3] xenfb: remove out_cons in xenfb_handle_events Wei Liu
     [not found] ` <1460457796-1779-2-git-send-email-wei.liu2@citrix.com>
2016-04-12 17:12   ` [PATCH v2 1/3] xenfb: use the correct condition to avoid excessive looping Stefano Stabellini
     [not found]   ` <alpine.DEB.2.10.1604121012110.23347@sstabellini-ThinkPad-X260>
2016-04-22 11:16     ` Anthony PERARD
     [not found]     ` <20160422111609.GB1885@perard.uk.xensource.com>
2016-04-22 11:19       ` Wei Liu
     [not found] ` <1460457796-1779-4-git-send-email-wei.liu2@citrix.com>
2016-04-12 17:33   ` [PATCH v2 3/3] xenfb: remove out_cons in xenfb_handle_events Stefano Stabellini

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