linux-kernel - [PATCH 1/1] usb: xhci: remove the use of xhci->addr

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Date:   Wed,  2 Nov 2016 10:30:36 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Mathias Nyman <mathias.nyman@...ux.intel.com>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Lu Baolu <baolu.lu@...ux.intel.com>
Subject: [PATCH 1/1] usb: xhci: remove the use of xhci->addr_dev

xhci->addr_dev is used for the completion of both address device
and enable slot commands. It's shared by enumerations of all USB
devices connected to an xhci host. Hence, it's just a source for
possible races. Since we've introduced command structure and the
command queue to xhci driver.  It is time to get rid of addr_dev
and use the completion in the command structure instead.

Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 drivers/usb/host/xhci-mem.c |  1 -
 drivers/usb/host/xhci.c     | 18 ++++++++++--------
 drivers/usb/host/xhci.h     |  1 -
 3 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index 6afe323..4c27828 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -2536,7 +2536,6 @@ int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
 	 * something other than the default (~1ms minimum between interrupts).
 	 * See section 5.5.1.2.
 	 */
-	init_completion(&xhci->addr_dev);
 	for (i = 0; i < MAX_HC_SLOTS; ++i)
 		xhci->devs[i] = NULL;
 	for (i = 0; i < USB_MAXCHILDREN; ++i) {
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index ad06243..e254af7 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -3683,20 +3683,19 @@ int xhci_alloc_dev(struct usb_hcd *hcd, struct usb_device *udev)
 	int ret, slot_id;
 	struct xhci_command *command;
 
-	command = xhci_alloc_command(xhci, false, false, GFP_KERNEL);
+	command = xhci_alloc_command(xhci, false, true, GFP_KERNEL);
 	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);
-	command->completion = &xhci->addr_dev;
 	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");
-		kfree(command);
+		xhci_free_command(xhci, command);
 		return 0;
 	}
 	xhci_ring_cmd_db(xhci);
@@ -3711,7 +3710,7 @@ int xhci_alloc_dev(struct usb_hcd *hcd, struct usb_device *udev)
 		xhci_err(xhci, "Max number of devices this xHCI host supports is %u.\n",
 				HCS_MAX_SLOTS(
 					readl(&xhci->cap_regs->hcs_params1)));
-		kfree(command);
+		xhci_free_command(xhci, command);
 		return 0;
 	}
 
@@ -3747,7 +3746,7 @@ int xhci_alloc_dev(struct usb_hcd *hcd, struct usb_device *udev)
 #endif
 
 
-	kfree(command);
+	xhci_free_command(xhci, command);
 	/* Is this a LS or FS device under a HS hub? */
 	/* Hub or peripherial? */
 	return 1;
@@ -3755,6 +3754,7 @@ int xhci_alloc_dev(struct usb_hcd *hcd, struct usb_device *udev)
 disable_slot:
 	/* Disable slot, if we can do it without mem alloc */
 	spin_lock_irqsave(&xhci->lock, flags);
+	kfree(command->completion);
 	command->completion = NULL;
 	command->status = 0;
 	if (!xhci_queue_slot_control(xhci, command, TRB_DISABLE_SLOT,
@@ -3818,14 +3818,13 @@ static int xhci_setup_device(struct usb_hcd *hcd, struct usb_device *udev,
 		}
 	}
 
-	command = xhci_alloc_command(xhci, false, false, GFP_KERNEL);
+	command = xhci_alloc_command(xhci, false, true, GFP_KERNEL);
 	if (!command) {
 		ret = -ENOMEM;
 		goto out;
 	}
 
 	command->in_ctx = virt_dev->in_ctx;
-	command->completion = &xhci->addr_dev;
 
 	slot_ctx = xhci_get_slot_ctx(xhci, virt_dev->in_ctx);
 	ctrl_ctx = xhci_get_input_control_ctx(virt_dev->in_ctx);
@@ -3943,7 +3942,10 @@ static int xhci_setup_device(struct usb_hcd *hcd, struct usb_device *udev,
 		       le32_to_cpu(slot_ctx->dev_state) & DEV_ADDR_MASK);
 out:
 	mutex_unlock(&xhci->mutex);
-	kfree(command);
+	if (command) {
+		kfree(command->completion);
+		kfree(command);
+	}
 	return ret;
 }
 
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index f945380..60f254a 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1583,7 +1583,6 @@ struct xhci_hcd {
 	/* slot enabling and address device helpers */
 	/* these are not thread safe so use mutex */
 	struct mutex mutex;
-	struct completion	addr_dev;
 	int slot_id;
 	/* For USB 3.0 LPM enable/disable. */
 	struct xhci_command		*lpm_command;
-- 
2.1.4