[PATCH] usb: xhci: tegra: fix sleep in atomic call

[Haotien Hsu]

From: Wayne Chang <waynec@xxxxxxxxxx>

When we set the OTG port to Host mode, we observed the following splat:
[  167.057718] BUG: sleeping function called from invalid context at
include/linux/sched/mm.h:229
[  167.057872] Workqueue: events tegra_xusb_usb_phy_work
[  167.057954] Call trace:
[  167.057962]  dump_backtrace+0x0/0x210
[  167.057996]  show_stack+0x30/0x50
[  167.058020]  dump_stack_lvl+0x64/0x84
[  167.058065]  dump_stack+0x14/0x34
[  167.058100]  __might_resched+0x144/0x180
[  167.058140]  __might_sleep+0x64/0xd0
[  167.058171]  slab_pre_alloc_hook.constprop.0+0xa8/0x110
[  167.058202]  __kmalloc_track_caller+0x74/0x2b0
[  167.058233]  kvasprintf+0xa4/0x190
[  167.058261]  kasprintf+0x58/0x90
[  167.058285]  tegra_xusb_find_port_node.isra.0+0x58/0xd0
[  167.058334]  tegra_xusb_find_port+0x38/0xa0
[  167.058380]  tegra_xusb_padctl_get_usb3_companion+0x38/0xd0
[  167.058430]  tegra_xhci_id_notify+0x8c/0x1e0
[  167.058473]  notifier_call_chain+0x88/0x100
[  167.058506]  atomic_notifier_call_chain+0x44/0x70
[  167.058537]  tegra_xusb_usb_phy_work+0x60/0xd0
[  167.058581]  process_one_work+0x1dc/0x4c0
[  167.058618]  worker_thread+0x54/0x410
[  167.058650]  kthread+0x188/0x1b0
[  167.058672]  ret_from_fork+0x10/0x20

The function tegra_xusb_padctl_get_usb3_companion eventually calls
tegra_xusb_find_port and this in turn calls kasprintf which might sleep
and so cannot be called from an atomic context.

Fix this by moving the call to tegra_xusb_padctl_get_usb3_companion to
the tegra_xhci_id_work function where it is really needed.

Signed-off-by: Wayne Chang <waynec@xxxxxxxxxx>
Signed-off-by: Haotien Hsu <haotienh@xxxxxxxxxx>
---
 drivers/usb/host/xhci-tegra.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/host/xhci-tegra.c b/drivers/usb/host/xhci-tegra.c
index 1ff22f675930..af0185bacc70 100644
--- a/drivers/usb/host/xhci-tegra.c
+++ b/drivers/usb/host/xhci-tegra.c
@@ -2,7 +2,7 @@
 /*
  * NVIDIA Tegra xHCI host controller driver
  *
- * Copyright (c) 2014-2020, NVIDIA CORPORATION. All rights reserved.
+ * Copyright (c) 2014-2023, NVIDIA CORPORATION. All rights reserved.
  * Copyright (C) 2014 Google, Inc.
  */
 
@@ -1360,6 +1360,10 @@ static void tegra_xhci_id_work(struct work_struct *work)
 
 	mutex_unlock(&tegra->lock);
 
+	tegra->otg_usb3_port = tegra_xusb_padctl_get_usb3_companion(
+							tegra->padctl,
+							tegra->otg_usb2_port);
+
 	if (tegra->host_mode) {
 		/* switch to host mode */
 		if (tegra->otg_usb3_port >= 0) {
@@ -1474,9 +1478,6 @@ static int tegra_xhci_id_notify(struct notifier_block *nb,
 	}
 
 	tegra->otg_usb2_port = tegra_xusb_get_usb2_port(tegra, usbphy);
-	tegra->otg_usb3_port = tegra_xusb_padctl_get_usb3_companion(
-							tegra->padctl,
-							tegra->otg_usb2_port);
 
 	tegra->host_mode = (usbphy->last_event == USB_EVENT_ID) ? true : false;
 
-- 
2.25.1