1 files changed, 35 insertions, 6 deletions

diff --git a/arch/x86/xen/multicalls.c b/arch/x86/xen/multicalls.c
index 5791eb2e3750..9efd1c6c9776 100644
--- a/arch/x86/xen/multicalls.c
+++ b/arch/x86/xen/multicalls.c
@@ -29,14 +29,14 @@
 #define MC_DEBUG        1
 
 #define MC_BATCH        32
-#define MC_ARGS         (MC_BATCH * 16 / sizeof(u64))
+#define MC_ARGS         (MC_BATCH * 16)
 
 struct mc_buffer {
         struct multicall_entry entries[MC_BATCH];
 #if MC_DEBUG
         struct multicall_entry debug[MC_BATCH];
 #endif
-        u64 args[MC_ARGS];
+        unsigned char args[MC_ARGS];
         struct callback {
                 void (*fn)(void *);
                 void *data;
@@ -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,
@@ -107,20 +108,48 @@ struct multicall_space __xen_mc_entry(size_t args)
 {
         struct mc_buffer *b = &__get_cpu_var(mc_buffer);
         struct multicall_space ret;
-        unsigned argspace = (args + sizeof(u64) - 1) / sizeof(u64);
+        unsigned argidx = roundup(b->argidx, sizeof(u64));
 
         BUG_ON(preemptible());
-        BUG_ON(argspace > MC_ARGS);
+        BUG_ON(b->argidx > MC_ARGS);
 
         if (b->mcidx == MC_BATCH ||
-            (b->argidx + argspace) > MC_ARGS)
+            (argidx + args) > MC_ARGS) {
                 xen_mc_flush();
+                argidx = roundup(b->argidx, sizeof(u64));
+        }
 
         ret.mc = &b->entries[b->mcidx];
         b->mcidx++;
+        ret.args = &b->args[argidx];
+        b->argidx = argidx + args;
+
+        BUG_ON(b->argidx > MC_ARGS);
+        return ret;
+}
+
+struct multicall_space xen_mc_extend_args(unsigned long op, size_t size)
+{
+        struct mc_buffer *b = &__get_cpu_var(mc_buffer);
+        struct multicall_space ret = { NULL, NULL };
+
+        BUG_ON(preemptible());
+        BUG_ON(b->argidx > MC_ARGS);
+
+        if (b->mcidx == 0)
+                return ret;
+
+        if (b->entries[b->mcidx - 1].op != op)
+                return ret;
+
+        if ((b->argidx + size) > MC_ARGS)
+                return ret;
+
+        ret.mc = &b->entries[b->mcidx - 1];
         ret.args = &b->args[b->argidx];
-        b->argidx += argspace;
+        b->argidx += size;
 
+        BUG_ON(b->argidx > MC_ARGS);
         return ret;
 }