net/mlx5: Discard command completions in internal error

Fix use after free when FW completion arrives while device is in
internal error state. Avoid calling completion handler in this case,
since the device will flush the command interface and trigger all
completions manually.

Kernel log:
------------[ cut here ]------------
refcount_t: underflow; use-after-free.
...
RIP: 0010:refcount_warn_saturate+0xd8/0xe0
...
Call Trace:
<IRQ>
? __warn+0x79/0x120
? refcount_warn_saturate+0xd8/0xe0
? report_bug+0x17c/0x190
? handle_bug+0x3c/0x60
? exc_invalid_op+0x14/0x70
? asm_exc_invalid_op+0x16/0x20
? refcount_warn_saturate+0xd8/0xe0
cmd_ent_put+0x13b/0x160 [mlx5_core]
mlx5_cmd_comp_handler+0x5f9/0x670 [mlx5_core]
cmd_comp_notifier+0x1f/0x30 [mlx5_core]
notifier_call_chain+0x35/0xb0
atomic_notifier_call_chain+0x16/0x20
mlx5_eq_async_int+0xf6/0x290 [mlx5_core]
notifier_call_chain+0x35/0xb0
atomic_notifier_call_chain+0x16/0x20
irq_int_handler+0x19/0x30 [mlx5_core]
__handle_irq_event_percpu+0x4b/0x160
handle_irq_event+0x2e/0x80
handle_edge_irq+0x98/0x230
__common_interrupt+0x3b/0xa0
common_interrupt+0x7b/0xa0
</IRQ>
<TASK>
asm_common_interrupt+0x22/0x40

Fixes: 51d138c ("net/mlx5: Fix health error state handling")
Signed-off-by: Akiva Goldberger <[email protected]>
Reviewed-by: Moshe Shemesh <[email protected]>
Signed-off-by: Tariq Toukan <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: Akiva Goldberger

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

@@ -1634,6 +1634,9 @@ static int cmd_comp_notifier(struct notifier_block *nb,
 	dev = container_of(cmd, struct mlx5_core_dev, cmd);
 	eqe = data;
 
+	if (dev->state == MLX5_DEVICE_STATE_INTERNAL_ERROR)
+		return NOTIFY_DONE;
+
 	mlx5_cmd_comp_handler(dev, be32_to_cpu(eqe->data.cmd.vector), false);
 
 	return NOTIFY_OK;