Index: head/sys/net/iflib.h
===================================================================
--- head/sys/net/iflib.h
+++ head/sys/net/iflib.h
@@ -373,8 +373,8 @@
 
 void iflib_io_tqg_attach(struct grouptask *gt, void *uniq, int cpu, char *name);
 
-void iflib_config_gtask_init(if_ctx_t ctx, struct grouptask *gtask,
-			     gtask_fn_t *fn, char *name);
+void iflib_config_gtask_init(void *ctx, struct grouptask *gtask,
+			     gtask_fn_t *fn, const char *name);
 
 void iflib_config_gtask_deinit(struct grouptask *gtask);
 
@@ -396,7 +396,7 @@
 void iflib_dma_free_multi(iflib_dma_info_t *dmalist, int count);
 
 
-struct mtx *iflib_ctx_lock_get(if_ctx_t);
+struct sx *iflib_ctx_lock_get(if_ctx_t);
 struct mtx *iflib_qset_lock_get(if_ctx_t, uint16_t);
 
 void iflib_led_create(if_ctx_t ctx);
Index: head/sys/net/iflib.c
===================================================================
--- head/sys/net/iflib.c
+++ head/sys/net/iflib.c
@@ -163,7 +163,7 @@
 	if_shared_ctx_t ifc_sctx;
 	struct if_softc_ctx ifc_softc_ctx;
 
-	struct mtx ifc_ctx_mtx;
+	struct sx ifc_ctx_sx;
 	struct mtx ifc_state_mtx;
 
 	uint16_t ifc_nhwtxqs;
@@ -537,10 +537,10 @@
 
 #define CTX_ACTIVE(ctx) ((if_getdrvflags((ctx)->ifc_ifp) & IFF_DRV_RUNNING))
 
-#define CTX_LOCK_INIT(_sc, _name)  mtx_init(&(_sc)->ifc_ctx_mtx, _name, "iflib ctx lock", MTX_DEF)
-#define CTX_LOCK(ctx) mtx_lock(&(ctx)->ifc_ctx_mtx)
-#define CTX_UNLOCK(ctx) mtx_unlock(&(ctx)->ifc_ctx_mtx)
-#define CTX_LOCK_DESTROY(ctx) mtx_destroy(&(ctx)->ifc_ctx_mtx)
+#define CTX_LOCK_INIT(_sc)  sx_init(&(_sc)->ifc_ctx_sx, "iflib ctx lock")
+#define CTX_LOCK(ctx) sx_xlock(&(ctx)->ifc_ctx_sx)
+#define CTX_UNLOCK(ctx) sx_xunlock(&(ctx)->ifc_ctx_sx)
+#define CTX_LOCK_DESTROY(ctx) sx_destroy(&(ctx)->ifc_ctx_sx)
 
 
 #define STATE_LOCK_INIT(_sc, _name)  mtx_init(&(_sc)->ifc_state_mtx, _name, "iflib state lock", MTX_DEF)
@@ -4277,7 +4277,9 @@
 		}
 	}
 
+	CTX_LOCK(ctx);
 	if ((err = IFDI_ATTACH_PRE(ctx)) != 0) {
+		CTX_UNLOCK(ctx);
 		device_printf(dev, "IFDI_ATTACH_PRE failed %d\n", err);
 		return (err);
 	}
@@ -4435,6 +4437,7 @@
 	if_setgetcounterfn(ctx->ifc_ifp, iflib_if_get_counter);
 	iflib_add_device_sysctl_post(ctx);
 	ctx->ifc_flags |= IFC_INIT_DONE;
+	CTX_UNLOCK(ctx);
 	return (0);
 fail_detach:
 	ether_ifdetach(ctx->ifc_ifp);
@@ -4445,6 +4448,7 @@
 	/* XXX free queues */
 fail:
 	IFDI_DETACH(ctx);
+	CTX_UNLOCK(ctx);
 	return (err);
 }
 
@@ -4711,8 +4715,7 @@
 
 	_iflib_assert(sctx);
 
-	CTX_LOCK_INIT(ctx, device_get_nameunit(ctx->ifc_dev));
-
+	CTX_LOCK_INIT(ctx);
 	STATE_LOCK_INIT(ctx, device_get_nameunit(ctx->ifc_dev));
 	ifp = ctx->ifc_ifp = if_gethandle(IFT_ETHER);
 	if (ifp == NULL) {
@@ -5457,8 +5460,8 @@
 }
 
 void
-iflib_config_gtask_init(if_ctx_t ctx, struct grouptask *gtask, gtask_fn_t *fn,
-	char *name)
+iflib_config_gtask_init(void *ctx, struct grouptask *gtask, gtask_fn_t *fn,
+	const char *name)
 {
 
 	GROUPTASK_INIT(gtask, 0, fn, ctx);
@@ -5538,11 +5541,11 @@
 	    info, 0, iflib_sysctl_int_delay, "I", description);
 }
 
-struct mtx *
+struct sx *
 iflib_ctx_lock_get(if_ctx_t ctx)
 {
 
-	return (&ctx->ifc_ctx_mtx);
+	return (&ctx->ifc_ctx_sx);
 }
 
 static int