2 files changed, 53 insertions, 19 deletions

diff --git a/arch/ia64/kernel/mca.c b/arch/ia64/kernel/mca.c
index 1ead5ea6c5ce..4b5daa3cc0fe 100644
--- a/arch/ia64/kernel/mca.c
+++ b/arch/ia64/kernel/mca.c
@@ -57,6 +57,9 @@
  *
  * 2006-09-15 Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
  *            Add printing support for MCA/INIT.
+ *
+ * 2007-04-27 Russ Anderson <rja@sgi.com>
+ *            Support multiple cpus going through OS_MCA in the same event.
  */
 #include <linux/types.h>
 #include <linux/init.h>
@@ -96,7 +99,6 @@
 #endif
 
 /* Used by mca_asm.S */
-u32                             ia64_mca_serialize;
 DEFINE_PER_CPU(u64, ia64_mca_data); /* == __per_cpu_mca[smp_processor_id()] */
 DEFINE_PER_CPU(u64, ia64_mca_per_cpu_pte); /* PTE to map per-CPU area */
 DEFINE_PER_CPU(u64, ia64_mca_pal_pte);      /* PTE to map PAL code */
@@ -963,11 +965,12 @@ ia64_mca_modify_original_stack(struct pt_regs *regs,
                 goto no_mod;
         }
 
+        if (r13 != sos->prev_IA64_KR_CURRENT) {
+                msg = "inconsistent previous current and r13";
+                goto no_mod;
+        }
+
         if (!mca_recover_range(ms->pmsa_iip)) {
-                if (r13 != sos->prev_IA64_KR_CURRENT) {
-                        msg = "inconsistent previous current and r13";
-                        goto no_mod;
-                }
                 if ((r12 - r13) >= KERNEL_STACK_SIZE) {
                         msg = "inconsistent r12 and r13";
                         goto no_mod;
@@ -1187,6 +1190,13 @@ all_in:
  *      further MCA logging is enabled by clearing logs.
  *      Monarch also has the duty of sending wakeup-IPIs to pull the
  *      slave processors out of rendezvous spinloop.
+ *
+ *      If multiple processors call into OS_MCA, the first will become
+ *      the monarch.  Subsequent cpus will be recorded in the mca_cpu
+ *      bitmask.  After the first monarch has processed its MCA, it
+ *      will wake up the next cpu in the mca_cpu bitmask and then go
+ *      into the rendezvous loop.  When all processors have serviced
+ *      their MCA, the last monarch frees up the rest of the processors.
  */
 void
 ia64_mca_handler(struct pt_regs *regs, struct switch_stack *sw,
@@ -1196,16 +1206,32 @@ ia64_mca_handler(struct pt_regs *regs, struct switch_stack *sw,
         struct task_struct *previous_current;
         struct ia64_mca_notify_die nd =
                 { .sos = sos, .monarch_cpu = &monarch_cpu };
+        static atomic_t mca_count;
+        static cpumask_t mca_cpu;
 
+        if (atomic_add_return(1, &mca_count) == 1) {
+                monarch_cpu = cpu;
+                sos->monarch = 1;
+        } else {
+                cpu_set(cpu, mca_cpu);
+                sos->monarch = 0;
+        }
         mprintk(KERN_INFO "Entered OS MCA handler. PSP=%lx cpu=%d "
                 "monarch=%ld\n", sos->proc_state_param, cpu, sos->monarch);
 
         previous_current = ia64_mca_modify_original_stack(regs, sw, sos, "MCA");
-        monarch_cpu = cpu;
+
         if (notify_die(DIE_MCA_MONARCH_ENTER, "MCA", regs, (long)&nd, 0, 0)
                         == NOTIFY_STOP)
                 ia64_mca_spin(__FUNCTION__);
-        ia64_wait_for_slaves(cpu, "MCA");
+        if (sos->monarch) {
+                ia64_wait_for_slaves(cpu, "MCA");
+        } else {
+                ia64_mc_info.imi_rendez_checkin[cpu] = IA64_MCA_RENDEZ_CHECKIN_CONCURRENT_MCA;
+                while (cpu_isset(cpu, mca_cpu))
+                        cpu_relax();    /* spin until monarch wakes us */
+                ia64_mc_info.imi_rendez_checkin[cpu] = IA64_MCA_RENDEZ_CHECKIN_NOTDONE;
+        }
 
         /* Wakeup all the processors which are spinning in the rendezvous loop.
          * They will leave SAL, then spin in the OS with interrupts disabled
@@ -1244,6 +1270,26 @@ ia64_mca_handler(struct pt_regs *regs, struct switch_stack *sw,
                         == NOTIFY_STOP)
                 ia64_mca_spin(__FUNCTION__);
 
+
+        if (atomic_dec_return(&mca_count) > 0) {
+                int i;
+
+                /* wake up the next monarch cpu,
+                 * and put this cpu in the rendez loop.
+                 */
+                ia64_mc_info.imi_rendez_checkin[cpu] = IA64_MCA_RENDEZ_CHECKIN_CONCURRENT_MCA;
+                for_each_online_cpu(i) {
+                        if (cpu_isset(i, mca_cpu)) {
+                                monarch_cpu = i;
+                                cpu_clear(i, mca_cpu);  /* wake next cpu */
+                                while (monarch_cpu != -1)
+                                        cpu_relax();    /* spin until last cpu leaves */
+                                ia64_mc_info.imi_rendez_checkin[cpu] = IA64_MCA_RENDEZ_CHECKIN_NOTDONE;
+                                set_curr_task(cpu, previous_current);
+                                return;
+                        }
+                }
+        }
         set_curr_task(cpu, previous_current);
         monarch_cpu = -1;
 }
diff --git a/arch/ia64/kernel/mca_asm.S b/arch/ia64/kernel/mca_asm.S
index 8c9c26aa6ae0..0f5965fcdf85 100644
--- a/arch/ia64/kernel/mca_asm.S
+++ b/arch/ia64/kernel/mca_asm.S
@@ -133,14 +133,6 @@ ia64_do_tlb_purge:
 //StartMain////////////////////////////////////////////////////////////////////
 
 ia64_os_mca_dispatch:
-        // Serialize all MCA processing
-        mov     r3=1;;
-        LOAD_PHYSICAL(p0,r2,ia64_mca_serialize);;
-ia64_os_mca_spin:
-        xchg4   r4=[r2],r3;;
-        cmp.ne  p6,p0=r4,r0
-(p6)    br ia64_os_mca_spin
-
         mov r3=IA64_MCA_CPU_MCA_STACK_OFFSET    // use the MCA stack
         LOAD_PHYSICAL(p0,r2,1f)                 // return address
         mov r19=1                               // All MCA events are treated as monarch (for now)
@@ -291,10 +283,6 @@ END(ia64_os_mca_virtual_begin)
 
         mov             b0=r12                  // SAL_CHECK return address
 
-        // release lock
-        LOAD_PHYSICAL(p0,r3,ia64_mca_serialize);;
-        st4.rel         [r3]=r0
-
         br              b0
 
 //EndMain//////////////////////////////////////////////////////////////////////