Creating debugfs files while loding the spin_lock_irqsave(xhci->lock)
creates a lock dependecy that could possibly deadlock.
Lockdep warns:
=====================================================
WARNING: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected
5.10.0-rc1pdx86+ #8 Not tainted
-----------------------------------------------------
systemd-udevd/386 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
ffffffffb1a94038 (pin_fs_lock){+.+.}-{2:2}, at: simple_pin_fs+0x22/0xa0
and this task is already holding:
ffff9e7b87fbc430 (&xhci->lock){-.-.}-{2:2}, at: xhci_alloc_streams+0x5f9/0x810
which would create a new lock dependency:
(&xhci->lock){-.-.}-{2:2} -> (pin_fs_lock){+.+.}-{2:2}
Create the files a bit later after lock is released.
Reported-by: Hans de Goede <hdegoede@xxxxxxxxxx>
Reported-by: Mike Galbraith <efault@xxxxxx>
Tested-by: Hans de Goede <hdegoede@xxxxxxxxxx>
CC: Li Jun <jun.li@xxxxxxx>
Fixes: 673d74683627 ("usb: xhci: add debugfs support for ep with stream")
Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
---
drivers/usb/host/xhci.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 482fe8c5e3b4..d4a8d0efbbc4 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -3533,11 +3533,14 @@ static int xhci_alloc_streams(struct usb_hcd *hcd, struct usb_device *udev,
xhci_dbg(xhci, "Slot %u ep ctx %u now has streams.\n",
udev->slot_id, ep_index);
vdev->eps[ep_index].ep_state |= EP_HAS_STREAMS;
- xhci_debugfs_create_stream_files(xhci, vdev, ep_index);
}
xhci_free_command(xhci, config_cmd);
spin_unlock_irqrestore(&xhci->lock, flags);
+ for (i = 0; i < num_eps; i++) {
+ ep_index = xhci_get_endpoint_index(&eps[i]->desc);
+ xhci_debugfs_create_stream_files(xhci, vdev, ep_index);
+ }
/* Subtract 1 for stream 0, which drivers can't use */
return num_streams - 1;
--
2.25.1
