This patch (as849) fixes a bug in the USB hub driver. A single
pre-allocated buffer is used for all port status reads, but nothing
guarantees exclusive use of the buffer. A mutex is added to provide
this guarantee.
Signed-off-by: Alan Stern <[EMAIL PROTECTED]>
---
This patch should go into Greg's USB development tree and into the
2.6.20-stable queue. It fixes the "usb somehow broken
(CONFIG_USB_SUSPEND)" bug reported by Prakash Punnoor.
The same bug is also present in earlier versions of the kernel, and so
this patch might also be added to those -stable trees. However in those
kernels the race it fixes is much less likely to occur.
Alan Stern
Index: usb-2.6/drivers/usb/core/hub.c
===================================================================
--- usb-2.6.orig/drivers/usb/core/hub.c
+++ usb-2.6/drivers/usb/core/hub.c
@@ -44,6 +44,7 @@ struct usb_hub {
struct usb_hub_status hub;
struct usb_port_status port;
} *status; /* buffer for status reports */
+ struct mutex status_mutex; /* for the status buffer */
int error; /* last reported error */
int nerrors; /* track consecutive errors */
@@ -535,6 +536,7 @@ static int hub_hub_status(struct usb_hub
{
int ret;
+ mutex_lock(&hub->status_mutex);
ret = get_hub_status(hub->hdev, &hub->status->hub);
if (ret < 0)
dev_err (hub->intfdev,
@@ -544,6 +546,7 @@ static int hub_hub_status(struct usb_hub
*change = le16_to_cpu(hub->status->hub.wHubChange);
ret = 0;
}
+ mutex_unlock(&hub->status_mutex);
return ret;
}
@@ -617,6 +620,7 @@ static int hub_configure(struct usb_hub
ret = -ENOMEM;
goto fail;
}
+ mutex_init(&hub->status_mutex);
hub->descriptor = kmalloc(sizeof(*hub->descriptor), GFP_KERNEL);
if (!hub->descriptor) {
@@ -1394,6 +1398,7 @@ static int hub_port_status(struct usb_hu
{
int ret;
+ mutex_lock(&hub->status_mutex);
ret = get_port_status(hub->hdev, port1, &hub->status->port);
if (ret < 4) {
dev_err (hub->intfdev,
@@ -1405,6 +1410,7 @@ static int hub_port_status(struct usb_hu
*change = le16_to_cpu(hub->status->port.wPortChange);
ret = 0;
}
+ mutex_unlock(&hub->status_mutex);
return ret;
}
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