From 712da5fc4a66fbb1f144742e1b808498e932009b Mon Sep 17 00:00:00 2001 From: Mathias Nyman Date: Wed, 28 Oct 2020 22:31:24 +0200 Subject: [PATCH] xhci: Don't create stream debugfs files with spinlock held. 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. Fixes: 673d74683627 ("usb: xhci: add debugfs support for ep with stream") CC: Li Jun Reported-by: Hans de Goede Reported-by: Mike Galbraith Tested-by: Hans de Goede Signed-off-by: Mathias Nyman Link: https://lore.kernel.org/r/20201028203124.375344-4-mathias.nyman@linux.intel.com Signed-off-by: Greg Kroah-Hartman --- 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;