svn commit: r356484 - head/sys/dev/virtio/network

[Kristof Provost]

Author: kp
Date: Wed Jan  8 10:06:32 2020
New Revision: 356484
URL: https://svnweb.freebsd.org/changeset/base/356484

Log:
  vtnet: Pre-allocate debugnet data immediately
  
  Don't wait until the vtnet_debugnet_init() call happens, because at that
  point we might already have allocated something from
  vtnet_tx_header_zone.
  
  Some systems showed this panic:
  
          vtnet0: link state changed to UP
          panic: keg vtnet_tx_hdr initialization after use.
          cpuid = 5
          time = 1578427700
          KDB: stack backtrace:
          db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe004db427f0
          vpanic() at vpanic+0x17e/frame 0xfffffe004db42850
          panic() at panic+0x43/frame 0xfffffe004db428b0
          uma_zone_reserve() at uma_zone_reserve+0xf6/frame 0xfffffe004db428f0
          vtnet_debugnet_init() at vtnet_debugnet_init+0x77/frame 0xfffffe004db42930
          debugnet_any_ifnet_update() at debugnet_any_ifnet_update+0x42/frame 0xfffffe004db42980
          do_link_state_change() at do_link_state_change+0x1b3/frame 0xfffffe004db429d0
          taskqueue_run_locked() at taskqueue_run_locked+0x178/frame 0xfffffe004db42a30
          taskqueue_run() at taskqueue_run+0x4d/frame 0xfffffe004db42a50
          ithread_loop() at ithread_loop+0x1d6/frame 0xfffffe004db42ab0
          fork_exit() at fork_exit+0x80/frame 0xfffffe004db42af0
          fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe004db42af0
          --- trap 0, rip = 0, rsp = 0, rbp = 0 ---
          KDB: enter: panic
          [ thread pid 12 tid 100011 ]
          Stopped at      kdb_enter+0x37: movq    $0,0x1084eb6(%rip)
          db>
  
  Reviewed by:	cem, markj
  Differential Revision:	https://reviews.freebsd.org/D23073

Modified:
  head/sys/dev/virtio/network/if_vtnet.c

Modified: head/sys/dev/virtio/network/if_vtnet.c
==============================================================================
--- head/sys/dev/virtio/network/if_vtnet.c	Wed Jan  8 07:25:37 2020	(r356483)
+++ head/sys/dev/virtio/network/if_vtnet.c	Wed Jan  8 10:06:32 2020	(r356484)
@@ -337,10 +337,21 @@ vtnet_modevent(module_t mod, int type, void *unused)
 
 	switch (type) {
 	case MOD_LOAD:
-		if (loaded++ == 0)
+		if (loaded++ == 0) {
 			vtnet_tx_header_zone = uma_zcreate("vtnet_tx_hdr",
 				sizeof(struct vtnet_tx_header),
 				NULL, NULL, NULL, NULL, 0, 0);
+#ifdef DEBUGNET
+			/*
+			 * We need to allocate from this zone in the transmit path, so ensure
+			 * that we have at least one item per header available.
+			 * XXX add a separate zone like we do for mbufs? otherwise we may alloc
+			 * buckets
+			 */
+			uma_zone_reserve(vtnet_tx_header_zone, DEBUGNET_MAX_IN_FLIGHT * 2);
+			uma_prealloc(vtnet_tx_header_zone, DEBUGNET_MAX_IN_FLIGHT * 2);
+#endif
+		}
 		break;
 	case MOD_QUIESCE:
 		if (uma_zone_get_cur(vtnet_tx_header_zone) > 0)
@@ -3982,15 +3993,6 @@ vtnet_debugnet_init(struct ifnet *ifp, int *nrxr, int 
 	*ncl = DEBUGNET_MAX_IN_FLIGHT;
 	*clsize = sc->vtnet_rx_clsize;
 	VTNET_CORE_UNLOCK(sc);
-
-	/*
-	 * We need to allocate from this zone in the transmit path, so ensure
-	 * that we have at least one item per header available.
-	 * XXX add a separate zone like we do for mbufs? otherwise we may alloc
-	 * buckets
-	 */
-	uma_zone_reserve(vtnet_tx_header_zone, DEBUGNET_MAX_IN_FLIGHT * 2);
-	uma_prealloc(vtnet_tx_header_zone, DEBUGNET_MAX_IN_FLIGHT * 2);
 }
 
 static void