xen: print backtrace on multicall failure

Print a backtrace if a multicall fails, to help with debugging.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/xen/multicalls.c b/arch/x86/xen/multicalls.c
index 3c63c4da7ed19cbe4ae43234fe6f6068eb638a79..9efd1c6c9776c5f9e8973026dd03b111c6e9e585 100644 (file)
--- a/arch/x86/xen/multicalls.c
+++ b/arch/x86/xen/multicalls.c
@@ -76,6 +76,7 @@ void xen_mc_flush(void)
                if (ret) {
                        printk(KERN_ERR "%d multicall(s) failed: cpu %d\n",
                               ret, smp_processor_id());
+                       dump_stack();
                        for (i = 0; i < b->mcidx; i++) {
                                printk("  call %2d/%d: op=%lu arg=[%lx] result=%ld\n",
                                       i+1, b->mcidx,