[PATCH v6 6/6] USB: forbid memory allocation with I/O during bus reset
From: Ming Lei <hidden>
Date: 2012-11-24 13:01:12
Also in:
linux-mm, linux-pm, lkml
Subsystem:
the rest, usb subsystem · Maintainers:
Linus Torvalds, Greg Kroah-Hartman
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 <stern@rowland.harvard.edu>
Cc: Oliver Neukum <redacted>
Signed-off-by: Ming Lei <redacted>
---
v5:
- use inline memalloc_noio_save()
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 90accde..2d5cc1c 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c@@ -5040,6 +5040,7 @@ 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 ||
@@ -5049,6 +5050,17 @@ 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. + */ + noio_flag = memalloc_noio_save(); + /* Prevent autosuspend during the reset */ usb_autoresume_device(udev);
@@ -5093,6 +5105,7 @@ 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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