If one storage interface or usb network interface(iSCSI case)
exists in current configuration, memory allocation with
GFP_KERNEL during usb_device_reset() might trigger I/O transfer
on the storage interface itself and cause deadlock because
the 'us->dev_mutex' is held in .pre_reset() and the storage
interface can't do I/O transfer when the reset is triggered
by other interface, or the error handling can't be completed
if the reset is triggered by the storage itself(error handling path).
Cc: Alan Stern <st...@rowland.harvard.edu>
Cc: Oliver Neukum <oneu...@suse.de>
Signed-off-by: Ming Lei <ming....@canonical.com>
---
v4:
- mark current memalloc_noio for every usb device reset
---
drivers/usb/core/hub.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 5b131b6..788e652 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -5044,6 +5044,7 @@ int usb_reset_device(struct usb_device *udev)
{
int ret;
int i;
+ unsigned int noio_flag;
struct usb_host_config *config = udev->actconfig;
if (udev->state == USB_STATE_NOTATTACHED ||
@@ -5053,6 +5054,17 @@ int usb_reset_device(struct usb_device *udev)
return -EINVAL;
}
+ /*
+ * Don't allocate memory with GFP_KERNEL in current
+ * context to avoid possible deadlock if usb mass
+ * storage interface or usbnet interface(iSCSI case)
+ * is included in current configuration. The easist
+ * approach is to do it for every device reset,
+ * because the device 'memalloc_noio' flag may have
+ * not been set before reseting the usb device.
+ */
+ memalloc_noio_save(noio_flag);
+
/* Prevent autosuspend during the reset */
usb_autoresume_device(udev);
@@ -5097,6 +5109,7 @@ int usb_reset_device(struct usb_device *udev)
}
usb_autosuspend_device(udev);
+ memalloc_noio_restore(noio_flag);
return ret;
}
EXPORT_SYMBOL_GPL(usb_reset_device);
--
1.7.9.5
--
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