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, 48 insertions, 49 deletions

diff --git a/drivers/usb/mon/mon_main.c b/drivers/usb/mon/mon_main.c
index 394bbf2f68d4..c9739e7b35e5 100644
--- a/drivers/usb/mon/mon_main.c
+++ b/drivers/usb/mon/mon_main.c
@@ -9,7 +9,6 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/usb.h>
-#include <linux/debugfs.h>
 #include <linux/smp_lock.h>
 #include <linux/notifier.h>
 #include <linux/mutex.h>
@@ -22,11 +21,10 @@ static void mon_complete(struct usb_bus *ubus, struct urb *urb);
 static void mon_stop(struct mon_bus *mbus);
 static void mon_dissolve(struct mon_bus *mbus, struct usb_bus *ubus);
 static void mon_bus_drop(struct kref *r);
-static void mon_bus_init(struct dentry *mondir, struct usb_bus *ubus);
+static void mon_bus_init(struct usb_bus *ubus);
 
 DEFINE_MUTEX(mon_lock);
 
-static struct dentry *mon_dir;          /* /dbg/usbmon */
 static LIST_HEAD(mon_buses);            /* All buses we know: struct mon_bus */
 
 /*
@@ -200,7 +198,7 @@ static void mon_stop(struct mon_bus *mbus)
  */
 static void mon_bus_add(struct usb_bus *ubus)
 {
-        mon_bus_init(mon_dir, ubus);
+        mon_bus_init(ubus);
 }
 
 /*
@@ -212,8 +210,8 @@ static void mon_bus_remove(struct usb_bus *ubus)
 
         mutex_lock(&mon_lock);
         list_del(&mbus->bus_link);
-        debugfs_remove(mbus->dent_t);
-        debugfs_remove(mbus->dent_s);
+        if (mbus->text_inited)
+                mon_text_del(mbus);
 
         mon_dissolve(mbus, ubus);
         kref_put(&mbus->ref, mon_bus_drop);
@@ -281,13 +279,9 @@ static void mon_bus_drop(struct kref *r)
  *  - refcount USB bus struct
  *  - link
  */
-static void mon_bus_init(struct dentry *mondir, struct usb_bus *ubus)
+static void mon_bus_init(struct usb_bus *ubus)
 {
-        struct dentry *d;
         struct mon_bus *mbus;
-        enum { NAMESZ = 10 };
-        char name[NAMESZ];
-        int rc;
 
         if ((mbus = kzalloc(sizeof(struct mon_bus), GFP_KERNEL)) == NULL)
                 goto err_alloc;
@@ -303,57 +297,54 @@ static void mon_bus_init(struct dentry *mondir, struct usb_bus *ubus)
         ubus->mon_bus = mbus;
         mbus->uses_dma = ubus->uses_dma;
 
-        rc = snprintf(name, NAMESZ, "%dt", ubus->busnum);
-        if (rc <= 0 || rc >= NAMESZ)
-                goto err_print_t;
-        d = debugfs_create_file(name, 0600, mondir, mbus, &mon_fops_text);
-        if (d == NULL)
-                goto err_create_t;
-        mbus->dent_t = d;
-
-        rc = snprintf(name, NAMESZ, "%ds", ubus->busnum);
-        if (rc <= 0 || rc >= NAMESZ)
-                goto err_print_s;
-        d = debugfs_create_file(name, 0600, mondir, mbus, &mon_fops_stat);
-        if (d == NULL)
-                goto err_create_s;
-        mbus->dent_s = d;
+        mbus->text_inited = mon_text_add(mbus, ubus);
+        // mon_bin_add(...)
 
         mutex_lock(&mon_lock);
         list_add_tail(&mbus->bus_link, &mon_buses);
         mutex_unlock(&mon_lock);
         return;
 
-err_create_s:
-err_print_s:
-        debugfs_remove(mbus->dent_t);
-err_create_t:
-err_print_t:
-        kfree(mbus);
 err_alloc:
         return;
 }
 
+/*
+ * Search a USB bus by number. Notice that USB bus numbers start from one,
+ * which we may later use to identify "all" with zero.
+ *
+ * This function must be called with mon_lock held.
+ *
+ * This is obviously inefficient and may be revised in the future.
+ */
+struct mon_bus *mon_bus_lookup(unsigned int num)
+{
+        struct list_head *p;
+        struct mon_bus *mbus;
+
+        list_for_each (p, &mon_buses) {
+                mbus = list_entry(p, struct mon_bus, bus_link);
+                if (mbus->u_bus->busnum == num) {
+                        return mbus;
+                }
+        }
+        return NULL;
+}
+
 static int __init mon_init(void)
 {
         struct usb_bus *ubus;
-        struct dentry *mondir;
+        int rc;
 
-        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;
+        if ((rc = mon_text_init()) != 0)
+                goto err_text;
+        if ((rc = mon_bin_init()) != 0)
+                goto err_bin;
 
         if (usb_mon_register(&mon_ops_0) != 0) {
                 printk(KERN_NOTICE TAG ": unable to register with the core\n");
-                debugfs_remove(mondir);
-                return -ENODEV;
+                rc = -ENODEV;
+                goto err_reg;
         }
         // MOD_INC_USE_COUNT(which_module?);
 
@@ -361,10 +352,17 @@ static int __init mon_init(void)
 
         mutex_lock(&usb_bus_list_lock);
         list_for_each_entry (ubus, &usb_bus_list, bus_list) {
-                mon_bus_init(mondir, ubus);
+                mon_bus_init(ubus);
         }
         mutex_unlock(&usb_bus_list_lock);
         return 0;
+
+err_reg:
+        mon_bin_exit();
+err_bin:
+        mon_text_exit();
+err_text:
+        return rc;
 }
 
 static void __exit mon_exit(void)
@@ -381,8 +379,8 @@ static void __exit mon_exit(void)
                 mbus = list_entry(p, struct mon_bus, bus_link);
                 list_del(p);
 
-                debugfs_remove(mbus->dent_t);
-                debugfs_remove(mbus->dent_s);
+                if (mbus->text_inited)
+                        mon_text_del(mbus);
 
                 /*
                  * This never happens, because the open/close paths in
@@ -401,7 +399,8 @@ static void __exit mon_exit(void)
         }
         mutex_unlock(&mon_lock);
 
-        debugfs_remove(mon_dir);
+        mon_text_exit();
+        mon_bin_exit();
 }
 
 module_init(mon_init);