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[Xen-changelog] [xen-3.0.3-testing] [BLKTAP] Remove unnecessary TLB flus

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Subject: [Xen-changelog] [xen-3.0.3-testing] [BLKTAP] Remove unnecessary TLB flush from blktap driver.
From: "Xen patchbot-3.0.3-testing" <patchbot-3.0.3-testing@xxxxxxxxxxxxxxxxxxx>
Date: Mon, 02 Oct 2006 12:40:48 -0700
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# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxx
# Date 1159525049 -3600
# Node ID 0c29e0d1c67bd92f1baff6b1a697ee5ea6f70e4d
# Parent  16759bdbd6c200f56c7588a9659f4f366638d4f6
[BLKTAP] Remove unnecessary TLB flush from blktap driver.

blktap_poll is calling tlb_flush_all() in its main ring buffer polling
loop.  This seems to be superfluous: the hypervisor should be
any necessary tlb flushes on grant table operations performed by the
back-end.  Even a simple memory barrier is unnecessary here as the
RING_PUSH_REQUESTS() call performs a wmb() anyway.

And tlb_flush_all() is not exported to modules, so this call prevents
blktap from building as a module.  Just remove it.

Signed-off-by: Stephen Tweedie <sct@xxxxxxxxxx>
 linux-2.6-xen-sparse/drivers/xen/blktap/blktap.c |    1 -
 1 files changed, 1 deletion(-)

diff -r 16759bdbd6c2 -r 0c29e0d1c67b 
--- a/linux-2.6-xen-sparse/drivers/xen/blktap/blktap.c  Fri Sep 29 11:16:52 
2006 +0100
+++ b/linux-2.6-xen-sparse/drivers/xen/blktap/blktap.c  Fri Sep 29 11:17:29 
2006 +0100
@@ -692,7 +692,6 @@ static unsigned int blktap_poll(struct f
        poll_wait(filp, &info->wait, wait);
        if (info->ufe_ring.req_prod_pvt != info->ufe_ring.sring->req_prod) {
-               flush_tlb_all();
                return POLLIN | POLLRDNORM;

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