svn commit: r246014 - in stable/9/sys/sparc64: include sparc64

[Marius Strobl]

Author: marius
Date: Sun Jan 27 23:21:47 2013
New Revision: 246014
URL: http://svnweb.freebsd.org/changeset/base/246014

Log:
  MFC: r245850
  
  Revert the part of r239864 (MFC'ed to stable/9 in r241681) which removed
  obtaining the SMP mutex around reading registers from other CPUs. As it
  turns out, the hardware doesn't really like concurrent IPI'ing causing
  adverse effects. Also the thought deadlock when using this spin lock here
  and the targeted CPU(s) are also holding or in case of nested locks can't
  actually happen. This is due to the fact that on sparc64, spinlock_enter()
  only raises the PIL but doesn't disable interrupts completely. Thus direct
  cross calls as used for the register reading (and all other MD IPI needs)
  still will be executed by the targeted CPU(s) in that case.

Modified:
  stable/9/sys/sparc64/include/smp.h
  stable/9/sys/sparc64/sparc64/tick.c
Directory Properties:
  stable/9/sys/   (props changed)

Modified: stable/9/sys/sparc64/include/smp.h
==============================================================================
--- stable/9/sys/sparc64/include/smp.h	Sun Jan 27 23:12:37 2013	(r246013)
+++ stable/9/sys/sparc64/include/smp.h	Sun Jan 27 23:21:47 2013	(r246014)
@@ -42,6 +42,7 @@
 #include <sys/cpuset.h>
 #include <sys/proc.h>
 #include <sys/sched.h>
+#include <sys/smp.h>
 
 #include <machine/intr_machdep.h>
 #include <machine/pcb.h>
@@ -202,6 +203,7 @@ ipi_rd(u_int cpu, void *func, u_long *va
 		return (NULL);
 	sched_pin();
 	ira = &ipi_rd_args;
+	mtx_lock_spin(&smp_ipi_mtx);
 	CPU_SETOF(cpu, &ira->ira_mask);
 	ira->ira_val = val;
 	cpu_ipi_single(cpu, 0, (u_long)func, (u_long)ira);
@@ -298,18 +300,6 @@ ipi_wait(void *cookie)
 	}
 }
 
-static __inline void
-ipi_wait_unlocked(void *cookie)
-{
-	volatile cpuset_t *mask;
-
-	if ((mask = cookie) != NULL) {
-		while (!CPU_EMPTY(mask))
-			;
-		sched_unpin();
-	}
-}
-
 #endif /* _MACHINE_PMAP_H_ && _SYS_MUTEX_H_ */
 
 #endif /* !LOCORE */
@@ -368,12 +358,6 @@ ipi_wait(void *cookie __unused)
 }
 
 static __inline void
-ipi_wait_unlocked(void *cookie __unused)
-{
-
-}
-
-static __inline void
 tl_ipi_cheetah_dcache_page_inval(void)
 {
 

Modified: stable/9/sys/sparc64/sparc64/tick.c
==============================================================================
--- stable/9/sys/sparc64/sparc64/tick.c	Sun Jan 27 23:12:37 2013	(r246013)
+++ stable/9/sys/sparc64/sparc64/tick.c	Sun Jan 27 23:21:47 2013	(r246014)
@@ -334,7 +334,7 @@ stick_get_timecount_mp(struct timecounte
 	if (curcpu == 0)
 		stick = rdstick();
 	else
-		ipi_wait_unlocked(ipi_rd(0, tl_ipi_stick_rd, &stick));
+		ipi_wait(ipi_rd(0, tl_ipi_stick_rd, &stick));
 	sched_unpin();
 	return (stick);
 }
@@ -348,7 +348,7 @@ tick_get_timecount_mp(struct timecounter
 	if (curcpu == 0)
 		tick = rd(tick);
 	else
-		ipi_wait_unlocked(ipi_rd(0, tl_ipi_tick_rd, &tick));
+		ipi_wait(ipi_rd(0, tl_ipi_tick_rd, &tick));
 	sched_unpin();
 	return (tick);
 }