USB: add binary API to usbmon

This patch adds a new, "binary" API in addition to the old, text API usbmon
had before. The new API allows for less CPU use, and it allows to capture
all data from a packet where old API only captured 32 bytes at most. There
are some limitations and conditions to this, e.g. in case someone constructs
a URB with 1GB of data, it's not likely to be captured, because even the
huge buffers of the new reader are finite. Nonetheless, I expect this new
capability to capture all data for all real life scenarios.

The downside is, a special user mode application is required where cat(1)
worked before. I have sample code at http://people.redhat.com/zaitcev/linux/
and Paolo Abeni is working on patching libpcap.

This patch was initially written by Paolo and later I tweaked it, and
we had a little back-and-forth. So this is a jointly authored patch, but
I am submitting this I am responsible for the bugs.

Signed-off-by: Paolo Abeni <paolo.abeni@email.it>
Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 66 insertions, 1 deletions

diff --git a/drivers/usb/mon/mon_text.c b/drivers/usb/mon/mon_text.c
index 05cf2c9a8f84..d38a1279d9d9 100644
--- a/drivers/usb/mon/mon_text.c
+++ b/drivers/usb/mon/mon_text.c
@@ -9,6 +9,7 @@
 #include <linux/usb.h>
 #include <linux/time.h>
 #include <linux/mutex.h>
+#include <linux/debugfs.h>
 #include <asm/uaccess.h>
 
 #include "usb_mon.h"
@@ -63,6 +64,8 @@ struct mon_reader_text {
         char slab_name[SLAB_NAME_SZ];
 };
 
+static struct dentry *mon_dir;          /* Usually /sys/kernel/debug/usbmon */
+
 static void mon_text_ctor(void *, struct kmem_cache *, unsigned long);
 
 /*
@@ -436,7 +439,7 @@ static int mon_text_release(struct inode *inode, struct file *file)
         return 0;
 }
 
-const struct file_operations mon_fops_text = {
+static const struct file_operations mon_fops_text = {
         .owner =        THIS_MODULE,
         .open =         mon_text_open,
         .llseek =       no_llseek,
@@ -447,6 +450,47 @@ const struct file_operations mon_fops_text = {
         .release =      mon_text_release,
 };
 
+int mon_text_add(struct mon_bus *mbus, const struct usb_bus *ubus)
+{
+        struct dentry *d;
+        enum { NAMESZ = 10 };
+        char name[NAMESZ];
+        int rc;
+
+        rc = snprintf(name, NAMESZ, "%dt", ubus->busnum);
+        if (rc <= 0 || rc >= NAMESZ)
+                goto err_print_t;
+        d = debugfs_create_file(name, 0600, mon_dir, mbus, &mon_fops_text);
+        if (d == NULL)
+                goto err_create_t;
+        mbus->dent_t = d;
+
+        /* XXX The stats do not belong to here (text API), but oh well... */
+        rc = snprintf(name, NAMESZ, "%ds", ubus->busnum);
+        if (rc <= 0 || rc >= NAMESZ)
+                goto err_print_s;
+        d = debugfs_create_file(name, 0600, mon_dir, mbus, &mon_fops_stat);
+        if (d == NULL)
+                goto err_create_s;
+        mbus->dent_s = d;
+
+        return 1;
+
+err_create_s:
+err_print_s:
+        debugfs_remove(mbus->dent_t);
+        mbus->dent_t = NULL;
+err_create_t:
+err_print_t:
+        return 0;
+}
+
+void mon_text_del(struct mon_bus *mbus)
+{
+        debugfs_remove(mbus->dent_t);
+        debugfs_remove(mbus->dent_s);
+}
+
 /*
  * Slab interface: constructor.
  */
@@ -459,3 +503,24 @@ static void mon_text_ctor(void *mem, struct kmem_cache *slab, unsigned long sfla
         memset(mem, 0xe5, sizeof(struct mon_event_text));
 }
 
+int __init mon_text_init(void)
+{
+        struct dentry *mondir;
+
+        mondir = debugfs_create_dir("usbmon", NULL);
+        if (IS_ERR(mondir)) {
+                printk(KERN_NOTICE TAG ": debugfs is not available\n");
+                return -ENODEV;
+        }
+        if (mondir == NULL) {
+                printk(KERN_NOTICE TAG ": unable to create usbmon directory\n");
+                return -ENODEV;
+        }
+        mon_dir = mondir;
+        return 0;
+}
+
+void __exit mon_text_exit(void)
+{
+        debugfs_remove(mon_dir);
+}