RDMA/counter: Prevent auto-binding a QP which are not tracked with res

Some QPs (e.g. XRC QP) are not tracked in kernel, in this case they have
an invalid res and should not be bound to any dynamically-allocated
counter in auto mode.

This fixes below call trace:
BUG: kernel NULL pointer dereference, address: 0000000000000390
PGD 80000001a7233067 P4D 80000001a7233067 PUD 1a7215067 PMD 0
Oops: 0000 [#1] SMP PTI
CPU: 2 PID: 24822 Comm: ibv_xsrq_pingpo Not tainted 5.4.0-rc5+ linux-sunxi#21
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-2.fc27 04/01/2014
RIP: 0010:rdma_counter_bind_qp_auto+0x142/0x270 [ib_core]
Code: e1 48 85 c0 48 89 c2 0f 84 bc 00 00 00 49 8b 06 48 39 42 48 75 d6 40 3a aa 90 00 00 00 75 cd 49 8b 86 00 01 00 00 48 8b 4a 28 <8b> 80 90 03 00 00 39 81 90 03 00 00 75 b4 85 c0 74 b0 48 8b 04 24
RSP: 0018:ffffc900003f39c0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000
RDX: ffff88820020ec00 RSI: 0000000000000004 RDI: ffffffffffffffc0
RBP: 0000000000000001 R08: ffff888224149ff0 R09: ffffc900003f3968
R10: ffffffffffffffff R11: ffff8882249c5848 R12: ffffffffffffffff
R13: ffff88821d5aca50 R14: ffff8881f7690800 R15: ffff8881ff890000
FS:  00007fe53a3e1740(0000) GS:ffff888237b00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000390 CR3: 00000001a7292006 CR4: 00000000003606a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 _ib_modify_qp+0x3a4/0x3f0 [ib_core]
 ? lookup_get_idr_uobject.part.8+0x23/0x40 [ib_uverbs]
 modify_qp+0x322/0x3e0 [ib_uverbs]
 ib_uverbs_modify_qp+0x43/0x70 [ib_uverbs]
 ib_uverbs_handler_UVERBS_METHOD_INVOKE_WRITE+0xb1/0xf0 [ib_uverbs]
 ib_uverbs_run_method+0x6be/0x760 [ib_uverbs]
 ? uverbs_disassociate_api+0xd0/0xd0 [ib_uverbs]
 ib_uverbs_cmd_verbs+0x18d/0x3a0 [ib_uverbs]
 ? get_acl+0x1a/0x120
 ? __alloc_pages_nodemask+0x15d/0x2c0
 ib_uverbs_ioctl+0xa7/0x110 [ib_uverbs]
 do_vfs_ioctl+0xa5/0x610
 ksys_ioctl+0x60/0x90
 __x64_sys_ioctl+0x16/0x20
 do_syscall_64+0x48/0x110
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fixes: 99fa331 ("RDMA/counter: Add "auto" configuration mode support")
Signed-off-by: Mark Zhang <markz@mellanox.com>
Reviewed-by: Maor Gottlieb <maorg@mellanox.com>
Reviewed-by: Ido Kalir <idok@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Link: https://lore.kernel.org/r/20191212091214.315005-2-leon@kernel.org
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/core/counters.c

@@ -286,6 +286,9 @@ int rdma_counter_bind_qp_auto(struct ib_qp *qp, u8 port)
 	struct rdma_counter *counter;
 	int ret;
 
+	if (!qp->res.valid)
+		return 0;
+
 	if (!rdma_is_port_valid(dev, port))
 		return -EINVAL;