From: Matthew Dillon <dillon@apollo.backplane.com>
Date: Thu, 11 Oct 2012 06:43:03 +0000 (-0700)
Subject: kernel - Use atomic op for usched_global_cpumask
X-Git-Tag: v3.4.0rc~999^2
X-Git-Url: https://gitweb.dragonflybsd.org/~tuxillo/dragonfly.git/commitdiff_plain/cb31dff3c5e12b338b6832cfde4445d76ea2b317

kernel - Use atomic op for usched_global_cpumask

* Use atomic op for usched_global_cpumask in the cpu init code.  This
  code is serialized anyway, I think, but it is best to be safe.

* Add cpu_ccfence() to ensure that the compiler does not reorder the
  clearing of the mask in the cpusync code.
---

diff --git a/sys/kern/init_main.c b/sys/kern/init_main.c
index e6951bbe0f..e26994eaba 100644
--- a/sys/kern/init_main.c
+++ b/sys/kern/init_main.c
@@ -719,6 +719,6 @@ mi_gdinit(struct globaldata *gd, int cpuid)
 	lwkt_gdinit(gd);
 	vm_map_entry_reserve_cpu_init(gd);
 	sleep_gdinit(gd);
-	usched_global_cpumask |= CPUMASK(cpuid);
+	atomic_set_cpumask(&usched_global_cpumask, CPUMASK(cpuid));
 }
 
diff --git a/sys/kern/lwkt_ipiq.c b/sys/kern/lwkt_ipiq.c
index a7c31bc054..e8b326ead2 100644
--- a/sys/kern/lwkt_ipiq.c
+++ b/sys/kern/lwkt_ipiq.c
@@ -821,6 +821,7 @@ lwkt_cpusync_deinterlock(lwkt_cpusync_t cs)
     mask = cs->cs_mack;
     cpu_ccfence();
     cs->cs_mack = 0;
+    cpu_ccfence();
     if (cs->cs_func && (cs->cs_mask & gd->gd_cpumask))
 	    cs->cs_func(cs->cs_data);
     if (mask) {