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linux-next/drivers/usb/mon/usb_mon.h
Pete Zaitcev 4e9e920035 USB: usbmon: end ugly tricks with DMA peeking
This patch fixes crashes when usbmon attempts to access GART aperture.
The old code attempted to take a bus address and convert it into a
virtual address, which clearly was impossible on systems with actual
IOMMUs. Let us not persist in this foolishness, and use transfer_buffer
in all cases instead.

I think downsides are negligible. The ones I see are:
 - A driver may pass an address of one buffer down as transfer_buffer,
   and entirely different entity mapped for DMA, resulting in misleading
   output of usbmon. Note, however, that PIO based controllers would
   do transfer the same data that usbmon sees here.
 - Out of tree drivers may crash usbmon if they store garbage in
   transfer_buffer. I inspected the in-tree drivers, and clarified
   the documentation in comments.
 - Drivers that use get_user_pages will not be possible to monitor.
   I only found one driver with this problem (drivers/staging/rspiusb).
 - Same happens with with usb_storage transferring from highmem, but
   it works fine on 64-bit systems, so I think it's not a concern.
   At least we don't crash anymore.

Why didn't we do this in 2.6.10? That's because back in those days
it was popular not to fill in transfer_buffer, so almost all
traffic would be invisible (e.g. all of HID was like that).
But now, the tree is almost 100% PIO friendly, so we can do the
right thing at last.

Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-09-23 06:46:19 -07:00

76 lines
1.9 KiB
C

/*
* The USB Monitor, inspired by Dave Harding's USBMon.
*
* Copyright (C) 2005 Pete Zaitcev (zaitcev@redhat.com)
*/
#ifndef __USB_MON_H
#define __USB_MON_H
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/kref.h>
/* #include <linux/usb.h> */ /* We use struct pointers only in this header */
#define TAG "usbmon"
struct mon_bus {
struct list_head bus_link;
spinlock_t lock;
struct usb_bus *u_bus;
int text_inited;
int bin_inited;
struct dentry *dent_s; /* Debugging file */
struct dentry *dent_t; /* Text interface file */
struct dentry *dent_u; /* Second text interface file */
struct device *classdev; /* Device in usbmon class */
/* Ref */
int nreaders; /* Under mon_lock AND mbus->lock */
struct list_head r_list; /* Chain of readers (usually one) */
struct kref ref; /* Under mon_lock */
/* Stats */
unsigned int cnt_events;
unsigned int cnt_text_lost;
};
/*
* An instance of a process which opened a file (but can fork later)
*/
struct mon_reader {
struct list_head r_link;
struct mon_bus *m_bus;
void *r_data; /* Use container_of instead? */
void (*rnf_submit)(void *data, struct urb *urb);
void (*rnf_error)(void *data, struct urb *urb, int error);
void (*rnf_complete)(void *data, struct urb *urb, int status);
};
void mon_reader_add(struct mon_bus *mbus, struct mon_reader *r);
void mon_reader_del(struct mon_bus *mbus, struct mon_reader *r);
struct mon_bus *mon_bus_lookup(unsigned int num);
int /*bool*/ mon_text_add(struct mon_bus *mbus, const struct usb_bus *ubus);
void mon_text_del(struct mon_bus *mbus);
int /*bool*/ mon_bin_add(struct mon_bus *mbus, const struct usb_bus *ubus);
void mon_bin_del(struct mon_bus *mbus);
int __init mon_text_init(void);
void mon_text_exit(void);
int __init mon_bin_init(void);
void mon_bin_exit(void);
/*
*/
extern struct mutex mon_lock;
extern const struct file_operations mon_fops_stat;
extern struct mon_bus mon_bus0; /* Only for redundant checks */
#endif /* __USB_MON_H */