[PATCH] USB: update usbmon, fix glued lines

This update contains one bug fix: some lines can come out truncated,
because of the safety cutoff. This happened because I forgot to update
the size when status packets began to be printed.

The rest is:
 - Comments updates
 - Allow snooping with pkmap on x86_64, which is cache-coherent
 - Enlarge event buffers (certainly we can have a couple of pages)
 - Add event counter

First touch upon usbmon for 2.6.18.
Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/mon/mon_dma.c

@@ -13,7 +13,10 @@
 #include <linux/usb.h>	/* Only needed for declarations in usb_mon.h */
 #include "usb_mon.h"
 
-#ifdef __i386__		/* CONFIG_ARCH_I386 does not exit */
+/*
+ * PC-compatibles, are, fortunately, sufficiently cache-coherent for this.
+ */
+#if defined(__i386__) || defined(__x86_64__) /* CONFIG_ARCH_I386 doesn't exit */
 #define MON_HAS_UNMAP 1
 
 #define phys_to_page(phys)	pfn_to_page((phys) >> PAGE_SHIFT)

drivers/usb/mon/mon_main.c

@@ -97,6 +97,7 @@ static void mon_submit(struct usb_bus *ubus, struct urb *urb)
 	if (mbus->nreaders == 0)
 		goto out_locked;
 
+	mbus->cnt_events++;
 	list_for_each (pos, &mbus->r_list) {
 		r = list_entry(pos, struct mon_reader, r_link);
 		r->rnf_submit(r->r_data, urb);
@@ -152,6 +153,7 @@ static void mon_complete(struct usb_bus *ubus, struct urb *urb)
 	}
 
 	spin_lock_irqsave(&mbus->lock, flags);
+	mbus->cnt_events++;
 	list_for_each (pos, &mbus->r_list) {
 		r = list_entry(pos, struct mon_reader, r_link);
 		r->rnf_complete(r->r_data, urb);
@@ -163,7 +165,6 @@ static void mon_complete(struct usb_bus *ubus, struct urb *urb)
 
 /*
  * Stop monitoring.
- * Obviously this must be well locked, so no need to play with mb's.
  */
 static void mon_stop(struct mon_bus *mbus)
 {

drivers/usb/mon/mon_stat.c

@@ -31,8 +31,8 @@ static int mon_stat_open(struct inode *inode, struct file *file)
 	mbus = inode->u.generic_ip;
 
 	sp->slen = snprintf(sp->str, STAT_BUF_SIZE,
-	    "nreaders %d text_lost %u\n",
-	    mbus->nreaders, mbus->cnt_text_lost);
+	    "nreaders %d events %u text_lost %u\n",
+	    mbus->nreaders, mbus->cnt_events, mbus->cnt_text_lost);
 
 	file->private_data = sp;
 	return 0;

drivers/usb/mon/mon_text.c

@@ -26,10 +26,13 @@
 
 /*
  * This limit exists to prevent OOMs when the user process stops reading.
+ * If usbmon were available to unprivileged processes, it might be open
+ * to a local DoS. But we have to keep to root in order to prevent
+ * password sniffing from HID devices.
  */
-#define EVENT_MAX  25
+#define EVENT_MAX  (2*PAGE_SIZE / sizeof(struct mon_event_text))
 
-#define PRINTF_DFL  130
+#define PRINTF_DFL  160
 
 struct mon_event_text {
 	struct list_head e_link;
@@ -111,7 +114,7 @@ static inline char mon_text_get_data(struct mon_event_text *ep, struct urb *urb,
 	 * number of corner cases, but it seems that the following is
 	 * more or less safe.
 	 *
-	 * We do not even try to look transfer_buffer, because it can
+	 * We do not even try to look at transfer_buffer, because it can
 	 * contain non-NULL garbage in case the upper level promised to
 	 * set DMA for the HCD.
 	 */

drivers/usb/mon/usb_mon.h

@@ -27,6 +27,7 @@ struct mon_bus {
 	struct kref ref;		/* Under mon_lock */
 
 	/* Stats */
+	unsigned int cnt_events;
 	unsigned int cnt_text_lost;
 };