Commit 089ed490 authored Oct 05, 2017 by Lu Baolu Committed by Greg Kroah-Hartman Oct 05, 2017

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: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg 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");

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