[Xen-changelog] [xen-unstable] [BLKTAP] Remove unnecessary TLB flush from blktap driver.

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxx
# 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
performing
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 
linux-2.6-xen-sparse/drivers/xen/blktap/blktap.c
--- 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();
                RING_PUSH_REQUESTS(&info->ufe_ring);
                return POLLIN | POLLRDNORM;
        }

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