[PATCH v4 0/5] usb: xhci: Handle USB transaction error on address command

[PATCH v4 0/5] usb: xhci: Handle USB transaction error on address command

[Lu Baolu]

Xhci driver handles USB transaction errors on transfer events,
but transaction errors are possible on address device command
completion events as well.

The xHCI specification (section 4.6.5) says: A USB Transaction
Error Completion Code for an Address Device Command may be due
to a Stall response from a device. Software should issue a Disable
Slot Command for the Device Slot then an Enable Slot Command to
recover from this error.

The related discussion threads can be found through below links.

http://marc.info/?l=linux-usb&m=149362010728921&w=2
http://marc.info/?l=linux-usb&m=149252752825755&w=2

This patch set includes some fixes in xhci_disable_slot() as well
which will be used to handle USB transaction error on address
command.

---
Change log:

v1->v2:
 - Add 4 fixes in xhci_disable_slot which will be used
   to handle USB transaction error on address command.

v2->v3:
 - Add checking virt dev for test mode in PATCH 1/5.

v3->v4:
 - Resolve xhci->mutex locking issue in 5/5.

Lu Baolu (5):
  usb: xhci: Disable slot even virt-dev is null
  usb: xhci: Fix potential memory leak in xhci_disable_slot()
  usb: xhci: Fix memory leak when xhci_disable_slot() returns error
  usb: xhci: Return error when host is dead in xhci_disable_slot()
  usb: xhci: Handle USB transaction error on address command

 drivers/usb/host/xhci-hub.c |  5 ++++-
 drivers/usb/host/xhci.c     | 54 +++++++++++++++++++--------------------------
 drivers/usb/host/xhci.h     |  3 +--
 3 files changed, 28 insertions(+), 34 deletions(-)

-- 
2.7.4

[PATCH v4 1/5] usb: xhci: Disable slot even virt-dev is null

[Lu Baolu]

xhci_disable_slot() is a helper for disabling a slot when a device
goes away or recovers from error situations. Currently, it checks
the corespoding virt-dev pointer and returns directly (w/o issuing
disable slot command) if it's null.

This is unnecessary and will cause problems in case where virt-dev
allocation fails and xhci_disable_slot() is called to roll back the
hardware state. Refer to the implementation of xhci_alloc_dev().

This patch removes lines to check virt-dev in xhci_disable_slot().

Fixes: f9e609b82479 ("usb: xhci: Add helper function xhci_disable_slot().")
Cc: Guoqing Zhang <guoqing.zhang@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/usb/host/xhci-hub.c | 3 +++
 drivers/usb/host/xhci.c     | 4 ----
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
index 00721e8..6fcb98d 100644
--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -612,6 +612,9 @@ static int xhci_enter_test_mode(struct xhci_hcd *xhci,
 	xhci_dbg(xhci, "Disable all slots\n");
 	spin_unlock_irqrestore(&xhci->lock, *flags);
 	for (i = 1; i <= HCS_MAX_SLOTS(xhci->hcs_params1); i++) {
+		if (!xhci->devs[i])
+			continue;
+
 		retval = xhci_disable_slot(xhci, NULL, i);
 		if (retval)
 			xhci_err(xhci, "Failed to disable slot %d, %d. Enter test mode anyway\n",
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index b2ff1ff..e69073f 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -3567,11 +3567,7 @@ int xhci_disable_slot(struct xhci_hcd *xhci, struct xhci_command *command,
 	unsigned long flags;
 	u32 state;
 	int ret = 0;
-	struct xhci_virt_device *virt_dev;
 
-	virt_dev = xhci->devs[slot_id];
-	if (!virt_dev)
-		return -EINVAL;
 	if (!command)
 		command = xhci_alloc_command(xhci, false, false, GFP_KERNEL);
 	if (!command)
-- 
2.7.4

[PATCH v4 2/5] usb: xhci: Fix potential memory leak in xhci_disable_slot()

[Lu Baolu]

xhci_disable_slot() allows the invoker to pass a command pointer
as paramenter. Otherwise, it will allocate one. This will cause
memory leak when a command structure was allocated inside of this
function while queuing command trb fails. Another problem comes up
when the invoker passed a command pointer, but xhci_disable_slot()
frees it when it detects a dead host.

This patch fixes these two problems by removing the command parameter
from xhci_disable_slot().

Fixes: f9e609b82479 ("usb: xhci: Add helper function xhci_disable_slot().")
Cc: Guoqing Zhang <guoqing.zhang@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/usb/host/xhci-hub.c |  2 +-
 drivers/usb/host/xhci.c     | 30 +++++++++---------------------
 drivers/usb/host/xhci.h     |  3 +--
 3 files changed, 11 insertions(+), 24 deletions(-)

diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
index 6fcb98d..daaf155 100644
--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -615,7 +615,7 @@ static int xhci_enter_test_mode(struct xhci_hcd *xhci,
 		if (!xhci->devs[i])
 			continue;
 
-		retval = xhci_disable_slot(xhci, NULL, i);
+		retval = xhci_disable_slot(xhci, i);
 		if (retval)
 			xhci_err(xhci, "Failed to disable slot %d, %d. Enter test mode anyway\n",
 				 i, retval);
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index e69073f..cb2461a 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -3519,11 +3519,6 @@ static void xhci_free_dev(struct usb_hcd *hcd, struct usb_device *udev)
 	struct xhci_virt_device *virt_dev;
 	struct xhci_slot_ctx *slot_ctx;
 	int i, ret;
-	struct xhci_command *command;
-
-	command = xhci_alloc_command(xhci, false, false, GFP_KERNEL);
-	if (!command)
-		return;
 
 #ifndef CONFIG_USB_DEFAULT_PERSIST
 	/*
@@ -3539,10 +3534,8 @@ static void xhci_free_dev(struct usb_hcd *hcd, struct usb_device *udev)
 	/* If the host is halted due to driver unload, we still need to free the
 	 * device.
 	 */
-	if (ret <= 0 && ret != -ENODEV) {
-		kfree(command);
+	if (ret <= 0 && ret != -ENODEV)
 		return;
-	}
 
 	virt_dev = xhci->devs[udev->slot_id];
 	slot_ctx = xhci_get_slot_ctx(xhci, virt_dev->out_ctx);
@@ -3554,22 +3547,21 @@ static void xhci_free_dev(struct usb_hcd *hcd, struct usb_device *udev)
 		del_timer_sync(&virt_dev->eps[i].stop_cmd_timer);
 	}
 
-	xhci_disable_slot(xhci, command, udev->slot_id);
+	xhci_disable_slot(xhci, udev->slot_id);
 	/*
 	 * Event command completion handler will free any data structures
 	 * associated with the slot.  XXX Can free sleep?
 	 */
 }
 
-int xhci_disable_slot(struct xhci_hcd *xhci, struct xhci_command *command,
-			u32 slot_id)
+int xhci_disable_slot(struct xhci_hcd *xhci, u32 slot_id)
 {
+	struct xhci_command *command;
 	unsigned long flags;
 	u32 state;
 	int ret = 0;
 
-	if (!command)
-		command = xhci_alloc_command(xhci, false, false, GFP_KERNEL);
+	command = xhci_alloc_command(xhci, false, false, GFP_KERNEL);
 	if (!command)
 		return -ENOMEM;
 
@@ -3588,7 +3580,7 @@ int xhci_disable_slot(struct xhci_hcd *xhci, struct xhci_command *command,
 				slot_id);
 	if (ret) {
 		spin_unlock_irqrestore(&xhci->lock, flags);
-		xhci_dbg(xhci, "FIXME: allocate a command ring segment\n");
+		kfree(command);
 		return ret;
 	}
 	xhci_ring_cmd_db(xhci);
@@ -3663,6 +3655,8 @@ int xhci_alloc_dev(struct usb_hcd *hcd, struct usb_device *udev)
 		return 0;
 	}
 
+	xhci_free_command(xhci, command);
+
 	if ((xhci->quirks & XHCI_EP_LIMIT_QUIRK)) {
 		spin_lock_irqsave(&xhci->lock, flags);
 		ret = xhci_reserve_host_control_ep_resources(xhci);
@@ -3698,18 +3692,12 @@ int xhci_alloc_dev(struct usb_hcd *hcd, struct usb_device *udev)
 		pm_runtime_get_noresume(hcd->self.controller);
 #endif
 
-
-	xhci_free_command(xhci, command);
 	/* Is this a LS or FS device under a HS hub? */
 	/* Hub or peripherial? */
 	return 1;
 
 disable_slot:
-	/* Disable slot, if we can do it without mem alloc */
-	kfree(command->completion);
-	command->completion = NULL;
-	command->status = 0;
-	return xhci_disable_slot(xhci, command, udev->slot_id);
+	return xhci_disable_slot(xhci, udev->slot_id);
 }
 
 /*
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index e3e9352..6325d58 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -2003,8 +2003,7 @@ int xhci_run(struct usb_hcd *hcd);
 int xhci_gen_setup(struct usb_hcd *hcd, xhci_get_quirks_t get_quirks);
 void xhci_init_driver(struct hc_driver *drv,
 		      const struct xhci_driver_overrides *over);
-int xhci_disable_slot(struct xhci_hcd *xhci,
-			struct xhci_command *command, u32 slot_id);
+int xhci_disable_slot(struct xhci_hcd *xhci, u32 slot_id);
 
 int xhci_suspend(struct xhci_hcd *xhci, bool do_wakeup);
 int xhci_resume(struct xhci_hcd *xhci, bool hibernated);
-- 
2.7.4

[PATCH v4 3/5] usb: xhci: Fix memory leak when xhci_disable_slot() returns error

[Lu Baolu]

If xhci_disable_slot() returns success, a disable slot command
trb was queued in the command ring. The command completion
handler will free the virtual device data structure associated
with the slot. On the other hand, when xhci_disable_slot()
returns error, the invokers should take the responsibilities to
free the slot related data structure. Otherwise, memory leakage
happens.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/usb/host/xhci.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index cb2461a..2df601e 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -3547,11 +3547,9 @@ static void xhci_free_dev(struct usb_hcd *hcd, struct usb_device *udev)
 		del_timer_sync(&virt_dev->eps[i].stop_cmd_timer);
 	}
 
-	xhci_disable_slot(xhci, udev->slot_id);
-	/*
-	 * Event command completion handler will free any data structures
-	 * associated with the slot.  XXX Can free sleep?
-	 */
+	ret = xhci_disable_slot(xhci, udev->slot_id);
+	if (ret)
+		xhci_free_virt_device(xhci, udev->slot_id);
 }
 
 int xhci_disable_slot(struct xhci_hcd *xhci, u32 slot_id)
@@ -3697,7 +3695,11 @@ int xhci_alloc_dev(struct usb_hcd *hcd, struct usb_device *udev)
 	return 1;
 
 disable_slot:
-	return xhci_disable_slot(xhci, udev->slot_id);
+	ret = xhci_disable_slot(xhci, udev->slot_id);
+	if (ret)
+		xhci_free_virt_device(xhci, udev->slot_id);
+
+	return 0;
 }
 
 /*
-- 
2.7.4

[PATCH v4 4/5] usb: xhci: Return error when host is dead in xhci_disable_slot()

[Lu Baolu]

xhci_disable_slot() is a helper for disabling a slot when a device
goes away or recovers from error situations. Currently, it returns
success when it sees a dead host. This is not the right way to go.
It should return error and let the invoker know that disable slot
command was failed due to a dead host.

Fixes: f9e609b82479 ("usb: xhci: Add helper function xhci_disable_slot().")
Cc: Guoqing Zhang <guoqing.zhang@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/usb/host/xhci.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 2df601e..d6b728d 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -3568,10 +3568,9 @@ int xhci_disable_slot(struct xhci_hcd *xhci, u32 slot_id)
 	state = readl(&xhci->op_regs->status);
 	if (state == 0xffffffff || (xhci->xhc_state & XHCI_STATE_DYING) ||
 			(xhci->xhc_state & XHCI_STATE_HALTED)) {
-		xhci_free_virt_device(xhci, slot_id);
 		spin_unlock_irqrestore(&xhci->lock, flags);
 		kfree(command);
-		return ret;
+		return -ENODEV;
 	}
 
 	ret = xhci_queue_slot_control(xhci, command, TRB_DISABLE_SLOT,
-- 
2.7.4

[PATCH v4 5/5] usb: xhci: Handle USB transaction error on address command

[Lu Baolu]

Xhci driver handles USB transaction errors on transfer events,
but transaction errors are possible on address device command
completion events as well.

The xHCI specification (section 4.6.5) says: A USB Transaction
Error Completion Code for an Address Device Command may be due
to a Stall response from a device. Software should issue a Disable
Slot Command for the Device Slot then an Enable Slot Command to
recover from this error.

This patch handles USB transaction errors on address command
completion events. The related discussion threads can be found
through below links.

http://marc.info/?l=linux-usb&m=149362010728921&w=2
http://marc.info/?l=linux-usb&m=149252752825755&w=2

Suggested-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/usb/host/xhci.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index d6b728d..c8a64d2 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -3822,6 +3822,13 @@ static int xhci_setup_device(struct usb_hcd *hcd, struct usb_device *udev,
 		break;
 	case COMP_USB_TRANSACTION_ERROR:
 		dev_warn(&udev->dev, "Device not responding to setup %s.\n", act);
+
+		mutex_unlock(&xhci->mutex);
+		ret = xhci_disable_slot(xhci, udev->slot_id);
+		if (!ret)
+			xhci_alloc_dev(hcd, udev);
+		mutex_lock(&xhci->mutex);
+
 		ret = -EPROTO;
 		break;
 	case COMP_INCOMPATIBLE_DEVICE_ERROR:
-- 
2.7.4