[RFC PATCH v2 6/6] USB: forbid memory allocation with I/O during bus reset
From: Ming Lei <hidden>
Date: 2012-10-22 08:36:34
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> --- drivers/usb/core/hub.c | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 522ad57..106a80a 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c@@ -5038,6 +5038,7 @@ 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 ||
@@ -5047,6 +5048,15 @@ 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 easiest + * approach is to do it for all devices. + */ + memalloc_noio_save(noio_flag); + /* Prevent autosuspend during the reset */ usb_autoresume_device(udev);
@@ -5091,6 +5101,7 @@ 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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