[PATCH rdma-rc 1/3] RDMA/mlx5: Use xa_lock_irqsave when access to SRQ table

[Leon Romanovsky <leon@kernel.org>]

From: Maor Gottlieb <maorg@mellanox.com>

SRQ table is accessed both from interrupt and process context,
therefore we must use xa_lock_irqsave.

 [ 9878.321379] --------------------------------
 [ 9878.322349] inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage.
 [ 9878.323667] kworker/u17:9/8573 [HC0[0]:SC0[0]:HE1:SE1] takes:
 [ 9878.324894] ffff8883e3503d30 (&xa->xa_lock#13){?...}-{2:2}, at:
mlx5_cmd_get_srq+0x18/0x70 [mlx5_ib]
 [ 9878.326816] {IN-HARDIRQ-W} state was registered at:
 [ 9878.327905]   lock_acquire+0xb9/0x3a0
 [ 9878.328720]   _raw_spin_lock+0x25/0x30
 [ 9878.329475]   srq_event_notifier+0x2b/0xc0 [mlx5_ib]
 [ 9878.330433]   notifier_call_chain+0x45/0x70
 [ 9878.331393]   __atomic_notifier_call_chain+0x69/0x100
 [ 9878.332530]   forward_event+0x36/0xc0 [mlx5_core]
 [ 9878.333558]   notifier_call_chain+0x45/0x70
 [ 9878.334418]   __atomic_notifier_call_chain+0x69/0x100
 [ 9878.335498]   mlx5_eq_async_int+0xc5/0x160 [mlx5_core]
 [ 9878.336543]   notifier_call_chain+0x45/0x70
 [ 9878.337354]   __atomic_notifier_call_chain+0x69/0x100
 [ 9878.338337]   mlx5_irq_int_handler+0x19/0x30 [mlx5_core]
 [ 9878.339369]   __handle_irq_event_percpu+0x43/0x2a0
 [ 9878.340382]   handle_irq_event_percpu+0x30/0x70
 [ 9878.341252]   handle_irq_event+0x34/0x60
 [ 9878.342020]   handle_edge_irq+0x7c/0x1b0
 [ 9878.342788]   do_IRQ+0x60/0x110
 [ 9878.343482]   ret_from_intr+0x0/0x2a
 [ 9878.344251]   default_idle+0x34/0x160
 [ 9878.344996]   do_idle+0x1ec/0x220
 [ 9878.345682]   cpu_startup_entry+0x19/0x20
 [ 9878.346511]   start_secondary+0x153/0x1a0
 [ 9878.347328]   secondary_startup_64+0xa4/0xb0
 [ 9878.348226] irq event stamp: 20907
 [ 9878.348953] hardirqs last  enabled at (20907): [<ffffffff819f0eb4>]
_raw_spin_unlock_irq+0x24/0x30
 [ 9878.350599] hardirqs last disabled at (20906): [<ffffffff819f0cbf>]
_raw_spin_lock_irq+0xf/0x40
 [ 9878.352300] softirqs last  enabled at (20746): [<ffffffff81c002c9>]
__do_softirq+0x2c9/0x436
 [ 9878.353859] softirqs last disabled at (20681): [<ffffffff81139543>]
irq_exit+0xb3/0xc0
 [ 9878.355365]
 [ 9878.355365] other info that might help us debug this:
 [ 9878.356703]  Possible unsafe locking scenario:
 [ 9878.356703]
 [ 9878.357941]        CPU0
 [ 9878.358522]        ----
 [ 9878.359109]   lock(&xa->xa_lock#13);
 [ 9878.359875]   <Interrupt>
 [ 9878.360504]     lock(&xa->xa_lock#13);
 [ 9878.361315]
 [ 9878.361315]  *** DEADLOCK ***
 [ 9878.361315]
 [ 9878.362632] 2 locks held by kworker/u17:9/8573:
 [ 9878.374883]  #0: ffff888295218d38
((wq_completion)mlx5_ib_page_fault){+.+.}-{0:0}, at:
process_one_work+0x1f1/0x5f0
 [ 9878.376728]  #1: ffff888401647e78
((work_completion)(&pfault->work)){+.+.}-{0:0}, at:
process_one_work+0x1f1/0x5f0
 [ 9878.378550]
 [ 9878.378550] stack backtrace:
 [ 9878.379489] CPU: 0 PID: 8573 Comm: kworker/u17:9 Tainted: G
O      5.7.0_for_upstream_min_debug_2020_06_14_11_31_46_41 #1
 [ 9878.381730] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014
 [ 9878.383940] Workqueue: mlx5_ib_page_fault mlx5_ib_eqe_pf_action
[mlx5_ib]
 [ 9878.385239] Call Trace:
 [ 9878.385822]  dump_stack+0x71/0x9b
 [ 9878.386519]  mark_lock+0x4f2/0x590
 [ 9878.387263]  ? print_shortest_lock_dependencies+0x200/0x200
 [ 9878.388362]  __lock_acquire+0xa00/0x1eb0
 [ 9878.389133]  lock_acquire+0xb9/0x3a0
 [ 9878.389854]  ? mlx5_cmd_get_srq+0x18/0x70 [mlx5_ib]
 [ 9878.390796]  _raw_spin_lock+0x25/0x30
 [ 9878.391533]  ? mlx5_cmd_get_srq+0x18/0x70 [mlx5_ib]
 [ 9878.392455]  mlx5_cmd_get_srq+0x18/0x70 [mlx5_ib]
 [ 9878.393351]  mlx5_ib_eqe_pf_action+0x257/0xa30 [mlx5_ib]
 [ 9878.394337]  ? process_one_work+0x209/0x5f0
 [ 9878.395150]  process_one_work+0x27b/0x5f0
 [ 9878.395939]  ? __schedule+0x280/0x7e0
 [ 9878.396683]  worker_thread+0x2d/0x3c0
 [ 9878.397424]  ? process_one_work+0x5f0/0x5f0
 [ 9878.398249]  kthread+0x111/0x130
 [ 9878.398926]  ? kthread_park+0x90/0x90
 [ 9878.399709]  ret_from_fork+0x24/0x30

Fixes: b02a29eb8841 ("mlx5: Convert mlx5_srq_table to XArray")
Signed-off-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
---
 drivers/infiniband/hw/mlx5/srq_cmd.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/infiniband/hw/mlx5/srq_cmd.c b/drivers/infiniband/hw/mlx5/srq_cmd.c
index 6f5eadc4d183..be0e5469dad0 100644
--- a/drivers/infiniband/hw/mlx5/srq_cmd.c
+++ b/drivers/infiniband/hw/mlx5/srq_cmd.c
@@ -82,12 +82,13 @@ struct mlx5_core_srq *mlx5_cmd_get_srq(struct mlx5_ib_dev *dev, u32 srqn)
 {
 	struct mlx5_srq_table *table = &dev->srq_table;
 	struct mlx5_core_srq *srq;
+	unsigned long flags;
 
-	xa_lock(&table->array);
+	xa_lock_irqsave(&table->array, flags);
 	srq = xa_load(&table->array, srqn);
 	if (srq)
 		refcount_inc(&srq->common.refcount);
-	xa_unlock(&table->array);
+	xa_unlock_irqrestore(&table->array, flags);
 
 	return srq;
 }
@@ -644,6 +645,7 @@ static int srq_event_notifier(struct notifier_block *nb,
 	struct mlx5_srq_table *table;
 	struct mlx5_core_srq *srq;
 	struct mlx5_eqe *eqe;
+	unsigned long flags;
 	u32 srqn;
 
 	if (type != MLX5_EVENT_TYPE_SRQ_CATAS_ERROR &&
@@ -655,11 +657,11 @@ static int srq_event_notifier(struct notifier_block *nb,
 	eqe = data;
 	srqn = be32_to_cpu(eqe->data.qp_srq.qp_srq_n) & 0xffffff;
 
-	xa_lock(&table->array);
+	xa_lock_irqsave(&table->array, flags);
 	srq = xa_load(&table->array, srqn);
 	if (srq)
 		refcount_inc(&srq->common.refcount);
-	xa_unlock(&table->array);
+	xa_unlock_irqrestore(&table->array, flags);
 
 	if (!srq)
 		return NOTIFY_OK;
-- 
2.26.2