ixgbevf: make netif_napi_add and netif_napi_del symmetric

ixgbevf_alloc_q_vectors() calls netif_napi_add for each qvector
where qvectors is determined by the number of msix vectors. This
makes perfect sense.

However on cleanup when ixgbevf_free_q_vectors() is called and
for each qvector we should call netif_napi_del there is some
extra logic to add a dependency on RX queues. This patch makes
the add/del operations symmetric by removing the RX queues
dependency.

Without this if  free_netdev() is called we see the general
protection fault below in netif_napi_del when list_del_init()
is called.

# addr2line -e ./vmlinux ffffffff8140810c
net-next/include/linux/list.h:88

general protection fault: 0000 [#1] SMP
Modules linked in: bonding ixgbevf ixgbe(-) mdio libfc scsi_transport_fc scsi_tgt 8021q garp stp llc cpufreq_ondemand acpi_cpufreq freq_table mperf ipv6 uinput coretemp lpc_ich i2c_i801 shpchp hwmon i2c_core serio_raw crc32c_intel mfd_core joydev pcspkr microcode ioatdma igb dca pata_acpi ata_generic usb_storage pata_jmicron [last unloaded: bonding]
CPU 10
Pid: 4174, comm: rmmod Tainted: G        W    3.6.0-rc3jk-net-next+ #104 Supermicro X8DTN/X8DTN
RIP: 0010:[<ffffffff8140810c>]  [<ffffffff8140810c>] netif_napi_del+0x24/0x87
RSP: 0018:ffff88027f5e9b48  EFLAGS: 00010293
RAX: ffff8806224b4768 RBX: ffff8806224b46e8 RCX: 6b6b6b6b6b6b6b6b
RDX: 6b6b6b6b6b6b6b6b RSI: ffffffff810bf6c5 RDI: ffff8806224b46e8
RBP: ffff88027f5e9b58 R08: ffff88033200b180 R09: ffff88027f5e98a8
R10: ffff88033320b000 R11: ffff88027f5e9ae8 R12: 6b6b6b6b6b6b6aeb
R13: ffff8806221d11c0 R14: 0000000000000000 R15: ffff88027f5e9cf8
FS:  00007f5e58b9b700(0000) GS:ffff880333200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 00000000010ef2b8 CR3: 0000000281fff000 CR4: 00000000000007e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process rmmod (pid: 4174, threadinfo ffff88027f5e8000, task ffff88032f888000)
Stack:
 ffff8806221d1160 6b6b6b6b6b6b6aeb ffff88027f5e9b88 ffffffff81408e46
 ffff8806221d1160 ffff8806221d1160 ffff8806221d1ae0 ffff8806221d5668
 ffff88027f5e9bb8 ffffffffa009153c ffffffffa0092a30 ffff8806221d5700
Call Trace:
 [<ffffffff81408e46>] free_netdev+0x64/0xd7
 [<ffffffffa009153c>] ixgbevf_remove+0xa6/0xbc [ixgbevf]
 [<ffffffff8127a7a1>] pci_device_remove+0x2d/0x51
 [<ffffffff8131f503>] __device_release_driver+0x6c/0xc2
 [<ffffffff8131f640>] device_release_driver+0x25/0x32
 [<ffffffff8131e821>] bus_remove_device+0x148/0x15d
 [<ffffffff8131cb6b>] device_del+0x130/0x1a4
 [<ffffffff8131cc2a>] device_unregister+0x4b/0x57
 [<ffffffff81275c27>] pci_stop_bus_device+0x63/0x85
 [...]

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Acked-by: Greg Rose <gregory.v.rose@intel.com>
Acked-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Sibai Li <sibai.li@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c

@@ -1912,18 +1912,13 @@ err_out:
  **/
 static void ixgbevf_free_q_vectors(struct ixgbevf_adapter *adapter)
 {
-	int q_idx, num_q_vectors;
-	int napi_vectors;
-
-	num_q_vectors = adapter->num_msix_vectors - NON_Q_VECTORS;
-	napi_vectors = adapter->num_rx_queues;
+	int q_idx, num_q_vectors = adapter->num_msix_vectors - NON_Q_VECTORS;
 
 	for (q_idx = 0; q_idx < num_q_vectors; q_idx++) {
 		struct ixgbevf_q_vector *q_vector = adapter->q_vector[q_idx];
 
 		adapter->q_vector[q_idx] = NULL;
-		if (q_idx < napi_vectors)
-			netif_napi_del(&q_vector->napi);
+		netif_napi_del(&q_vector->napi);
 		kfree(q_vector);
 	}
 }