[Xen-changelog] [linux-2.6.18-xen] linux/x86: Use cpu_relax() rather than barrier() in smp_call_function()

["Xen patchbot-linux-2.6.18-xen" <patchbot-linux-2.6.18-xen@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1196956971 0
# Node ID 3938ff4b3fc2e84518719bea706a412983155a2a
# Parent  d43906ea0e9c136e9ec28df30f94c225536d588c
linux/x86: Use cpu_relax() rather than barrier() in smp_call_function()

Short of getting an explanation for the odd difference to native, make
the code match native (and also, in the case of x86-64,
__smp_call_function_single()).

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
---
 arch/i386/kernel/smp-xen.c   |    4 ++--
 arch/x86_64/kernel/smp-xen.c |    8 --------
 2 files changed, 2 insertions(+), 10 deletions(-)

diff -r d43906ea0e9c -r 3938ff4b3fc2 arch/i386/kernel/smp-xen.c
--- a/arch/i386/kernel/smp-xen.c        Thu Dec 06 15:59:52 2007 +0000
+++ b/arch/i386/kernel/smp-xen.c        Thu Dec 06 16:02:51 2007 +0000
@@ -525,11 +525,11 @@ int smp_call_function (void (*func) (voi
 
        /* Wait for response */
        while (atomic_read(&data.started) != cpus)
-               barrier();
+               cpu_relax();
 
        if (wait)
                while (atomic_read(&data.finished) != cpus)
-                       barrier();
+                       cpu_relax();
        spin_unlock(&call_lock);
 
        return 0;
diff -r d43906ea0e9c -r 3938ff4b3fc2 arch/x86_64/kernel/smp-xen.c
--- a/arch/x86_64/kernel/smp-xen.c      Thu Dec 06 15:59:52 2007 +0000
+++ b/arch/x86_64/kernel/smp-xen.c      Thu Dec 06 16:02:51 2007 +0000
@@ -421,21 +421,13 @@ static void __smp_call_function (void (*
 
        /* Wait for response */
        while (atomic_read(&data.started) != cpus)
-#ifndef CONFIG_XEN
                cpu_relax();
-#else
-               barrier();
-#endif
 
        if (!wait)
                return;
 
        while (atomic_read(&data.finished) != cpus)
-#ifndef CONFIG_XEN
                cpu_relax();
-#else
-               barrier();
-#endif
 }
 
 /*

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