Further tweak the changes made in r233709. The kernel doesn't permit

sleeping from a swi handler (even though in this case it would be ok), so
switch the refill and scanning SWI handlers to being tasks on a fast
taskqueue.  Also, only schedule the refill task for a CMCI as an MC# can
fire at any time, so it should do the minimal amount of work needed and
avoid opportunities to deadlock before it panics (such as scheduling a
task it won't ever need in practice).  To handle the case of an MC# only
finding recoverable errors (which should never happen), always try to
refill the event free list when the periodic scan executes.

MFC after:	2 weeks

1 files changed, 25 insertions, 14 deletions

diff --git a/sys/x86/x86/mca.c b/sys/x86/x86/mca.c
index 9887cc7..f1369cd 100644
--- a/sys/x86/x86/mca.c
+++ b/sys/x86/x86/mca.c
@@ -50,6 +50,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/smp.h>
 #include <sys/sysctl.h>
 #include <sys/systm.h>
+#include <sys/taskqueue.h>
 #include <machine/intr_machdep.h>
 #include <machine/apicvar.h>
 #include <machine/cputypes.h>
@@ -108,8 +109,9 @@ static int mca_freecount;
 static STAILQ_HEAD(, mca_internal) mca_records;
 static struct callout mca_timer;
 static int mca_ticks = 3600;	/* Check hourly by default. */
+static struct taskqueue *mca_tq;
+static struct task mca_refill_task, mca_scan_task;
 static struct mtx mca_lock;
-static void *mca_refill_swi, *mca_scan_swi;
 
 #ifdef DEV_APIC
 static struct cmc_state **cmc_state;	/* Indexed by cpuid, bank */
@@ -439,7 +441,7 @@ mca_fill_freelist(void)
 }
 
 static void
-mca_refill(void *arg)
+mca_refill(void *context, int pending)
 {
 
 	mca_fill_freelist();
@@ -464,8 +466,6 @@ mca_record_entry(enum scan_mode mode, const struct mca_record *record)
 		}
 		STAILQ_REMOVE_HEAD(&mca_freelist, link);
 		mca_freecount--;
-		if (mca_refill_swi != NULL)
-			swi_sched(mca_refill_swi, 0);
 	}
 
 	rec->rec = *record;
@@ -473,6 +473,8 @@ mca_record_entry(enum scan_mode mode, const struct mca_record *record)
 	STAILQ_INSERT_TAIL(&mca_records, rec, link);
 	mca_count++;
 	mtx_unlock_spin(&mca_lock);
+	if (mode == CMCI)
+		taskqueue_enqueue_fast(mca_tq, &mca_refill_task);
 }
 
 #ifdef DEV_APIC
@@ -616,12 +618,13 @@ mca_scan(enum scan_mode mode)
  * them to the console.
  */
 static void
-mca_scan_cpus(void *arg)
+mca_scan_cpus(void *context, int pending)
 {
 	struct mca_internal *mca;
 	struct thread *td;
 	int count, cpu;
 
+	mca_fill_freelist();
 	td = curthread;
 	count = 0;
 	thread_lock(td);
@@ -649,7 +652,7 @@ static void
 mca_periodic_scan(void *arg)
 {
 
-	swi_sched(mca_scan_swi, 1);
+	taskqueue_enqueue_fast(mca_tq, &mca_scan_task);
 	callout_reset(&mca_timer, mca_ticks * hz, mca_periodic_scan, NULL);
 }
 
@@ -663,23 +666,29 @@ sysctl_mca_scan(SYSCTL_HANDLER_ARGS)
 	if (error)
 		return (error);
 	if (i)
-		swi_sched(mca_scan_swi, 1);
+		taskqueue_enqueue_fast(mca_tq, &mca_scan_task);
 	return (0);
 }
 
 static void
+mca_createtq(void *dummy)
+{
+	if (mca_banks <= 0)
+		return;
+
+	mca_tq = taskqueue_create_fast("mca", M_WAITOK,
+	    taskqueue_thread_enqueue, &mca_tq);
+	taskqueue_start_threads(&mca_tq, 1, PI_SWI(SWI_TQ), "mca taskq");
+}
+SYSINIT(mca_createtq, SI_SUB_CONFIGURE, SI_ORDER_ANY, mca_createtq, NULL);
+
+static void
 mca_startup(void *dummy)
 {
-	struct intr_event *ie;
 
-	if (!mca_enabled || !(cpu_feature & CPUID_MCA))
+	if (mca_banks <= 0)
 		return;
 
-	ie = NULL;
-	swi_add(&ie, "mca:scan", mca_scan_cpus, NULL, SWI_TQ, INTR_MPSAFE,
-	    &mca_scan_swi);
-	swi_add(&ie, "mca:refill", mca_refill, NULL, SWI_TQ, INTR_MPSAFE,
-	    &mca_refill_swi);
 	callout_reset(&mca_timer, mca_ticks * hz, mca_periodic_scan, NULL);
 }
 SYSINIT(mca_startup, SI_SUB_SMP, SI_ORDER_ANY, mca_startup, NULL);
@@ -718,8 +727,10 @@ mca_setup(uint64_t mcg_cap)
 	mca_banks = mcg_cap & MCG_CAP_COUNT;
 	mtx_init(&mca_lock, "mca", NULL, MTX_SPIN);
 	STAILQ_INIT(&mca_records);
+	TASK_INIT(&mca_scan_task, 0, mca_scan_cpus, NULL);
 	callout_init(&mca_timer, CALLOUT_MPSAFE);
 	STAILQ_INIT(&mca_freelist);
+	TASK_INIT(&mca_refill_task, 0, mca_refill, NULL);
 	mca_fill_freelist();
 	SYSCTL_ADD_INT(NULL, SYSCTL_STATIC_CHILDREN(_hw_mca), OID_AUTO,
 	    "count", CTLFLAG_RD, &mca_count, 0, "Record count");