Simplify taskqgroup inititialization.

taskqgroup initialization was broken into two steps:

1. allocate the taskqgroup structure, at SI_SUB_TASKQ;
2. initialize taskqueues, start taskqueue threads, enqueue "binder"
   tasks to bind threads to specific CPUs, at SI_SUB_SMP.

Step 2 tries to handle the case where tasks have already been attached
to a queue, by migrating them to their intended queue.  In particular,
tasks can't be enqueued before step 2 has completed.  This breaks NFS
mountroot on systems using an iflib-based driver when EARLY_AP_STARTUP
is not defined, since mountroot happens before SI_SUB_SMP in this case.

Simplify initialization: do all initialization except for CPU binding at
SI_SUB_TASKQ.  This means that until CPU binding is completed, group
tasks may be executed on a CPU other than that to which they were bound,
but this should not be a problem for existing users of the taskqgroup
KPIs.

Reported by:	sbruno
Tested by:	bdragon, sbruno
MFC after:	1 month
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D24188

1 files changed, 0 insertions, 44 deletions

diff --git a/sys/net/iflib.c b/sys/net/iflib.c
index d6494eb89ee6..41f5a97eeeae 100644
--- a/sys/net/iflib.c
+++ b/sys/net/iflib.c
@@ -1410,29 +1410,6 @@ iflib_dma_free_multi(iflib_dma_info_t *dmalist, int count)
 		iflib_dma_free(*dmaiter);
 }
 
-#ifdef EARLY_AP_STARTUP
-static const int iflib_started = 1;
-#else
-/*
- * We used to abuse the smp_started flag to decide if the queues have been
- * fully initialized (by late taskqgroup_adjust() calls in a SYSINIT()).
- * That gave bad races, since the SYSINIT() runs strictly after smp_started
- * is set.  Run a SYSINIT() strictly after that to just set a usable
- * completion flag.
- */
-
-static int iflib_started;
-
-static void
-iflib_record_started(void *arg)
-{
-	iflib_started = 1;
-}
-
-SYSINIT(iflib_record_started, SI_SUB_SMP + 1, SI_ORDER_FIRST,
-	iflib_record_started, NULL);
-#endif
-
 static int
 iflib_fast_intr(void *arg)
 {
@@ -1440,9 +1417,6 @@ iflib_fast_intr(void *arg)
 	struct grouptask *gtask = info->ifi_task;
 	int result;
 
-	if (!iflib_started)
-		return (FILTER_STRAY);
-
 	DBG_COUNTER_INC(fast_intrs);
 	if (info->ifi_filter != NULL) {
 		result = info->ifi_filter(info->ifi_filter_arg);
@@ -1467,9 +1441,6 @@ iflib_fast_intr_rxtx(void *arg)
 	qidx_t txqid;
 	bool intr_enable, intr_legacy;
 
-	if (!iflib_started)
-		return (FILTER_STRAY);
-
 	DBG_COUNTER_INC(fast_intrs);
 	if (info->ifi_filter != NULL) {
 		result = info->ifi_filter(info->ifi_filter_arg);
@@ -1522,9 +1493,6 @@ iflib_fast_intr_ctx(void *arg)
 	struct grouptask *gtask = info->ifi_task;
 	int result;
 
-	if (!iflib_started)
-		return (FILTER_STRAY);
-
 	DBG_COUNTER_INC(fast_intrs);
 	if (info->ifi_filter != NULL) {
 		result = info->ifi_filter(info->ifi_filter_arg);
@@ -4746,18 +4714,6 @@ iflib_device_register(device_t dev, void *sc, if_shared_ctx_t sctx, if_ctx_t *ct
 	 */
 	ctx->ifc_sysctl_core_offset = get_ctx_core_offset(ctx);
 
-	/*
-	 * Group taskqueues aren't properly set up until SMP is started,
-	 * so we disable interrupts until we can handle them post
-	 * SI_SUB_SMP.
-	 *
-	 * XXX: disabling interrupts doesn't actually work, at least for
-	 * the non-MSI case.  When they occur before SI_SUB_SMP completes,
-	 * we do null handling and depend on this not causing too large an
-	 * interrupt storm.
-	 */
-	IFDI_INTR_DISABLE(ctx);
-
 	if (msix > 1) {
 		/*
 		 * When using MSI-X, ensure that ifdi_{r,t}x_queue_intr_enable