Author: nwhitehorn
Date: Wed Aug 24 16:49:14 2016
New Revision: 304756
URL: https://svnweb.freebsd.org/changeset/base/304756
Log:
Close a race when making the CPU idle under pHyp. If an interrupt occurs
between the beginning of the idle function and actually going idle, the
CPU could go to sleep with pending work.
MFC after: 1 month
Modified:
head/sys/powerpc/pseries/platform_chrp.c
Modified: head/sys/powerpc/pseries/platform_chrp.c
==============================================================================
--- head/sys/powerpc/pseries/platform_chrp.c Wed Aug 24 16:44:27 2016
(r304755)
+++ head/sys/powerpc/pseries/platform_chrp.c Wed Aug 24 16:49:14 2016
(r304756)
@@ -34,6 +34,7 @@ __FBSDID("$FreeBSD$");
#include <sys/bus.h>
#include <sys/pcpu.h>
#include <sys/proc.h>
+#include <sys/sched.h>
#include <sys/smp.h>
#include <vm/vm.h>
#include <vm/pmap.h>
@@ -492,7 +493,18 @@ chrp_reset(platform_t platform)
static void
phyp_cpu_idle(sbintime_t sbt)
{
- phyp_hcall(H_CEDE);
+ register_t msr;
+
+ msr = mfmsr();
+
+ mtmsr(msr & ~PSL_EE);
+ if (sched_runnable()) {
+ mtmsr(msr);
+ return;
+ }
+
+ phyp_hcall(H_CEDE); /* Re-enables interrupts internally */
+ mtmsr(msr);
}
static void
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