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Commit 089ed490 authored by Lu Baolu's avatar Lu Baolu Committed by Greg Kroah-Hartman
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usb: xhci: Remove xhci->mutex from xhci_alloc_dev() 

xhci->mutex was added in xhci_alloc_dev()  to protect two race sources
(xhci->slot_id and xhci->addr_dev) by commit a00918d0 ("usb: host:
xhci: add mutex for non-thread-safe data").

While xhci->slot_id has been discarded in commit c2d3d49b ("usb:
xhci: move slot_id from xhci_hcd to xhci_command structure"), and
xhci->addr_dev has been removed in commit 87e44f2a ("usb: xhci:
remove the use of xhci->addr_dev"), it's now safe to remove the use of
xhci->mutex in xhci_alloc_dev().

Link: https://marc.info/?l=linux-usb&m=150306294725821&w=2



Suggested-by: default avatarMathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: default avatarLu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: default avatarMathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent dcabc76f

drivers/usb/host/xhci.c

+0 −4
Original line number Diff line number Diff line
@@ -3639,13 +3639,10 @@ int xhci_alloc_dev(struct usb_hcd *hcd, struct usb_device *udev) 
	if (!command)

		return 0;



	/* xhci->slot_id and xhci->addr_dev are not thread-safe */

	mutex_lock(&xhci->mutex);

	spin_lock_irqsave(&xhci->lock, flags);

	ret = xhci_queue_slot_control(xhci, command, TRB_ENABLE_SLOT, 0);

	if (ret) {

		spin_unlock_irqrestore(&xhci->lock, flags);

		mutex_unlock(&xhci->mutex);

		xhci_dbg(xhci, "FIXME: allocate a command ring segment\n");

		xhci_free_command(xhci, command);

		return 0;
@@ -3655,7 +3652,6 @@ int xhci_alloc_dev(struct usb_hcd *hcd, struct usb_device *udev) 


	wait_for_completion(command->completion);

	slot_id = command->slot_id;

	mutex_unlock(&xhci->mutex);



	if (!slot_id || command->status != COMP_SUCCESS) {

		xhci_err(xhci, "Error while assigning device slot ID\n");