net/mlx5e: Check for NOT_READY flag state after locking

Currently the check for NOT_READY flag is performed before obtaining the
necessary lock. This opens a possibility for race condition when the flow
is concurrently removed from unready_flows list by the workqueue task,
which causes a double-removal from the list and a crash[0]. Fix the issue
by moving the flag check inside the section protected by
uplink_priv->unready_flows_lock mutex.

[0]:
[44376.389654] general protection fault, probably for non-canonical address 0xdead000000000108: 0000 [#1] SMP
[44376.391665] CPU: 7 PID: 59123 Comm: tc Not tainted 6.4.0-rc4+ #1
[44376.392984] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
[44376.395342] RIP: 0010:mlx5e_tc_del_fdb_flow+0xb3/0x340 [mlx5_core]
[44376.396857] Code: 00 48 8b b8 68 ce 02 00 e8 8a 4d 02 00 4c 8d a8 a8 01 00 00 4c 89 ef e8 8b 79 88 e1 48 8b 83 98 06 00 00 48 8b 93 90 06 00 00 <48> 89 42 08 48 89 10 48 b8 00 01 00 00 00 00 ad de 48 89 83 90 06
[44376.399167] RSP: 0018:ffff88812cc97570 EFLAGS: 00010246
[44376.399680] RAX: dead000000000122 RBX: ffff8881088e3800 RCX: ffff8881881bac00
[44376.400337] RDX: dead000000000100 RSI: ffff88812cc97500 RDI: ffff8881242f71b0
[44376.401001] RBP: ffff88811cbb0940 R08: 0000000000000400 R09: 0000000000000001
[44376.401663] R10: 0000000000000001 R11: 0000000000000000 R12: ffff88812c944000
[44376.402342] R13: ffff8881242f71a8 R14: ffff8881222b4000 R15: 0000000000000000
[44376.402999] FS:  00007f0451104800(0000) GS:ffff88852cb80000(0000) knlGS:0000000000000000
[44376.403787] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[44376.404343] CR2: 0000000000489108 CR3: 0000000123a79003 CR4: 0000000000370ea0
[44376.405004] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[44376.405665] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[44376.406339] Call Trace:
[44376.406651]  <TASK>
[44376.406939]  ? die_addr+0x33/0x90
[44376.407311]  ? exc_general_protection+0x192/0x390
[44376.407795]  ? asm_exc_general_protection+0x22/0x30
[44376.408292]  ? mlx5e_tc_del_fdb_flow+0xb3/0x340 [mlx5_core]
[44376.408876]  __mlx5e_tc_del_fdb_peer_flow+0xbc/0xe0 [mlx5_core]
[44376.409482]  mlx5e_tc_del_flow+0x42/0x210 [mlx5_core]
[44376.410055]  mlx5e_flow_put+0x25/0x50 [mlx5_core]
[44376.410529]  mlx5e_delete_flower+0x24b/0x350 [mlx5_core]
[44376.411043]  tc_setup_cb_reoffload+0x22/0x80
[44376.411462]  fl_reoffload+0x261/0x2f0 [cls_flower]
[44376.411907]  ? mlx5e_rep_indr_setup_ft_cb+0x160/0x160 [mlx5_core]
[44376.412481]  ? mlx5e_rep_indr_setup_ft_cb+0x160/0x160 [mlx5_core]
[44376.413044]  tcf_block_playback_offloads+0x76/0x170
[44376.413497]  tcf_block_unbind+0x7b/0xd0
[44376.413881]  tcf_block_setup+0x17d/0x1c0
[44376.414269]  tcf_block_offload_cmd.isra.0+0xf1/0x130
[44376.414725]  tcf_block_offload_unbind+0x43/0x70
[44376.415153]  __tcf_block_put+0x82/0x150
[44376.415532]  ingress_destroy+0x22/0x30 [sch_ingress]
[44376.415986]  qdisc_destroy+0x3b/0xd0
[44376.416343]  qdisc_graft+0x4d0/0x620
[44376.416706]  tc_get_qdisc+0x1c9/0x3b0
[44376.417074]  rtnetlink_rcv_msg+0x29c/0x390
[44376.419978]  ? rep_movs_alternative+0x3a/0xa0
[44376.420399]  ? rtnl_calcit.isra.0+0x120/0x120
[44376.420813]  netlink_rcv_skb+0x54/0x100
[44376.421192]  netlink_unicast+0x1f6/0x2c0
[44376.421573]  netlink_sendmsg+0x232/0x4a0
[44376.421980]  sock_sendmsg+0x38/0x60
[44376.422328]  ____sys_sendmsg+0x1d0/0x1e0
[44376.422709]  ? copy_msghdr_from_user+0x6d/0xa0
[44376.423127]  ___sys_sendmsg+0x80/0xc0
[44376.423495]  ? ___sys_recvmsg+0x8b/0xc0
[44376.423869]  __sys_sendmsg+0x51/0x90
[44376.424226]  do_syscall_64+0x3d/0x90
[44376.424587]  entry_SYSCALL_64_after_hwframe+0x46/0xb0
[44376.425046] RIP: 0033:0x7f045134f887
[44376.425403] Code: 0a 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b9 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 89 54 24 1c 48 89 74 24 10
[44376.426914] RSP: 002b:00007ffd63a82b98 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
[44376.427592] RAX: ffffffffffffffda RBX: 000000006481955f RCX: 00007f045134f887
[44376.428195] RDX: 0000000000000000 RSI: 00007ffd63a82c00 RDI: 0000000000000003
[44376.428796] RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
[44376.429404] R10: 00007f0451208708 R11: 0000000000000246 R12: 0000000000000001
[44376.430039] R13: 0000000000409980 R14: 000000000047e538 R15: 0000000000485400
[44376.430644]  </TASK>
[44376.430907] Modules linked in: mlx5_ib mlx5_core act_mirred act_tunnel_key cls_flower vxlan dummy sch_ingress openvswitch nsh rpcrdma rdma_ucm ib_iser libiscsi scsi_transport_iscsi ib_umad rdma_cm ib_ipoib iw_cm ib_cm ib_uverbs ib_core xt_conntrack xt_MASQUERADE nf_conntrack_netlink nfnetlink xt_addrtype iptable_nat nf_nat br_netfilter rpcsec_g
ss_krb5 auth_rpcgss oid_registry overlay zram zsmalloc fuse [last unloaded: mlx5_core]
[44376.433936] ---[ end trace 0000000000000000 ]---
[44376.434373] RIP: 0010:mlx5e_tc_del_fdb_flow+0xb3/0x340 [mlx5_core]
[44376.434951] Code: 00 48 8b b8 68 ce 02 00 e8 8a 4d 02 00 4c 8d a8 a8 01 00 00 4c 89 ef e8 8b 79 88 e1 48 8b 83 98 06 00 00 48 8b 93 90 06 00 00 <48> 89 42 08 48 89 10 48 b8 00 01 00 00 00 00 ad de 48 89 83 90 06
[44376.436452] RSP: 0018:ffff88812cc97570 EFLAGS: 00010246
[44376.436924] RAX: dead000000000122 RBX: ffff8881088e3800 RCX: ffff8881881bac00
[44376.437530] RDX: dead000000000100 RSI: ffff88812cc97500 RDI: ffff8881242f71b0
[44376.438179] RBP: ffff88811cbb0940 R08: 0000000000000400 R09: 0000000000000001
[44376.438786] R10: 0000000000000001 R11: 0000000000000000 R12: ffff88812c944000
[44376.439393] R13: ffff8881242f71a8 R14: ffff8881222b4000 R15: 0000000000000000
[44376.439998] FS:  00007f0451104800(0000) GS:ffff88852cb80000(0000) knlGS:0000000000000000
[44376.440714] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[44376.441225] CR2: 0000000000489108 CR3: 0000000123a79003 CR4: 0000000000370ea0
[44376.441843] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[44376.442471] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Fixes: ad86755 ("net/mlx5e: Protect unready flows with dedicated lock")
Signed-off-by: Vlad Buslov <[email protected]>
Reviewed-by: Roi Dayan <[email protected]>
Signed-off-by: Saeed Mahameed <[email protected]>

Author: w1ldptr

drivers/net/ethernet/mellanox/mlx5/core/en_tc.c

@@ -1639,7 +1639,8 @@ static void remove_unready_flow(struct mlx5e_tc_flow *flow)
 	uplink_priv = &rpriv->uplink_priv;
 
 	mutex_lock(&uplink_priv->unready_flows_lock);
-	unready_flow_del(flow);
+	if (flow_flag_test(flow, NOT_READY))
+		unready_flow_del(flow);
 	mutex_unlock(&uplink_priv->unready_flows_lock);
 }
 
@@ -1932,8 +1933,7 @@ static void mlx5e_tc_del_fdb_flow(struct mlx5e_priv *priv,
 	esw_attr = attr->esw_attr;
 	mlx5e_put_flow_tunnel_id(flow);
 
-	if (flow_flag_test(flow, NOT_READY))
-		remove_unready_flow(flow);
+	remove_unready_flow(flow);
 
 	if (mlx5e_is_offloaded_flow(flow)) {
 		if (flow_flag_test(flow, SLOW))