usbmon: bus zero

Add the "bus zero" feature to the usbmon. If a user process specifies bus
with number zero, it receives events from all buses. This is useful when
we wish to see initial enumeration when a bus is created, typically after
a modprobe. Until now, an application had to loop until a new bus could
be open, then start capturing on it. This procedure was cumbersome and
could lose initial events. Also, often it's too bothersome to find exactly
to which bus a specific device is attached.

Paolo Albeni provided the original concept implementation. I added the
handling of "bus->monitored" flag and generally fixed it up.

Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

4 files changed, 116 insertions, 84 deletions

diff --git a/drivers/usb/mon/mon_bin.c b/drivers/usb/mon/mon_bin.c
index b2bedd974ac3..0af11a66207c 100644
--- a/drivers/usb/mon/mon_bin.c
+++ b/drivers/usb/mon/mon_bin.c
@@ -356,8 +356,10 @@ static inline char mon_bin_get_setup(unsigned char *setupb,
         if (!usb_pipecontrol(urb->pipe) || ev_type != 'S')
                 return '-';
 
-        if (urb->transfer_flags & URB_NO_SETUP_DMA_MAP)
+        if (urb->dev->bus->uses_dma &&
+            (urb->transfer_flags & URB_NO_SETUP_DMA_MAP)) {
                 return mon_dmapeek(setupb, urb->setup_dma, SETUP_LEN);
+        }
         if (urb->setup_packet == NULL)
                 return 'Z';
 
@@ -369,7 +371,8 @@ static char mon_bin_get_data(const struct mon_reader_bin *rp,
     unsigned int offset, struct urb *urb, unsigned int length)
 {
 
-        if (urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP) {
+        if (urb->dev->bus->uses_dma &&
+            (urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)) {
                 mon_dmapeek_vec(rp, offset, urb->transfer_dma, length);
                 return 0;
         }
@@ -440,7 +443,7 @@ static void mon_bin_event(struct mon_reader_bin *rp, struct urb *urb,
         /* We use the fact that usb_pipein() returns 0x80 */
         ep->epnum = usb_pipeendpoint(urb->pipe) | usb_pipein(urb->pipe);
         ep->devnum = usb_pipedevice(urb->pipe);
-        ep->busnum = rp->r.m_bus->u_bus->busnum;
+        ep->busnum = urb->dev->bus->busnum;
         ep->id = (unsigned long) urb;
         ep->ts_sec = ts.tv_sec;
         ep->ts_usec = ts.tv_usec;
@@ -500,7 +503,7 @@ static void mon_bin_error(void *data, struct urb *urb, int error)
         /* We use the fact that usb_pipein() returns 0x80 */
         ep->epnum = usb_pipeendpoint(urb->pipe) | usb_pipein(urb->pipe);
         ep->devnum = usb_pipedevice(urb->pipe);
-        ep->busnum = rp->r.m_bus->u_bus->busnum;
+        ep->busnum = urb->dev->bus->busnum;
         ep->id = (unsigned long) urb;
         ep->status = error;
 
@@ -515,7 +518,6 @@ static void mon_bin_error(void *data, struct urb *urb, int error)
 static int mon_bin_open(struct inode *inode, struct file *file)
 {
         struct mon_bus *mbus;
-        struct usb_bus *ubus;
         struct mon_reader_bin *rp;
         size_t size;
         int rc;
@@ -525,7 +527,7 @@ static int mon_bin_open(struct inode *inode, struct file *file)
                 mutex_unlock(&mon_lock);
                 return -ENODEV;
         }
-        if ((ubus = mbus->u_bus) == NULL) {
+        if (mbus != &mon_bus0 && mbus->u_bus == NULL) {
                 printk(KERN_ERR TAG ": consistency error on open\n");
                 mutex_unlock(&mon_lock);
                 return -ENODEV;
diff --git a/drivers/usb/mon/mon_main.c b/drivers/usb/mon/mon_main.c
index c9739e7b35e5..8a1df2c9c73e 100644
--- a/drivers/usb/mon/mon_main.c
+++ b/drivers/usb/mon/mon_main.c
@@ -16,8 +16,6 @@
 #include "usb_mon.h"
 #include "../core/hcd.h"
 
-static void mon_submit(struct usb_bus *ubus, struct urb *urb);
-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);
@@ -25,6 +23,7 @@ static void mon_bus_init(struct usb_bus *ubus);
 
 DEFINE_MUTEX(mon_lock);
 
+struct mon_bus mon_bus0;                /* Pseudo bus meaning "all buses" */
 static LIST_HEAD(mon_buses);            /* All buses we know: struct mon_bus */
 
 /*
@@ -35,22 +34,19 @@ static LIST_HEAD(mon_buses);		/* All buses we know: struct mon_bus */
 void mon_reader_add(struct mon_bus *mbus, struct mon_reader *r)
 {
         unsigned long flags;
-        struct usb_bus *ubus;
+        struct list_head *p;
 
         spin_lock_irqsave(&mbus->lock, flags);
         if (mbus->nreaders == 0) {
-                ubus = mbus->u_bus;
-                if (ubus->monitored) {
-                        /*
-                         * Something is really broken, refuse to go on and
-                         * possibly corrupt ops pointers or worse.
-                         */
-                        printk(KERN_ERR TAG ": bus %d is already monitored\n",
-                            ubus->busnum);
-                        spin_unlock_irqrestore(&mbus->lock, flags);
-                        return;
+                if (mbus == &mon_bus0) {
+                        list_for_each (p, &mon_buses) {
+                                struct mon_bus *m1;
+                                m1 = list_entry(p, struct mon_bus, bus_link);
+                                m1->u_bus->monitored = 1;
+                        }
+                } else {
+                        mbus->u_bus->monitored = 1;
                 }
-                ubus->monitored = 1;
         }
         mbus->nreaders++;
         list_add_tail(&r->r_link, &mbus->r_list);
@@ -80,77 +76,79 @@ void mon_reader_del(struct mon_bus *mbus, struct mon_reader *r)
 
 /*
  */
-static void mon_submit(struct usb_bus *ubus, struct urb *urb)
+static void mon_bus_submit(struct mon_bus *mbus, struct urb *urb)
 {
-        struct mon_bus *mbus;
         unsigned long flags;
         struct list_head *pos;
         struct mon_reader *r;
 
-        mbus = ubus->mon_bus;
-        if (mbus == NULL)
-                goto out_unlocked;
-
         spin_lock_irqsave(&mbus->lock, flags);
-        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);
         }
-
         spin_unlock_irqrestore(&mbus->lock, flags);
         return;
+}
 
-out_locked:
-        spin_unlock_irqrestore(&mbus->lock, flags);
-out_unlocked:
-        return;
+static void mon_submit(struct usb_bus *ubus, struct urb *urb)
+{
+        struct mon_bus *mbus;
+
+        if ((mbus = ubus->mon_bus) != NULL)
+                mon_bus_submit(mbus, urb);
+        mon_bus_submit(&mon_bus0, urb);
 }
 
 /*
  */
-static void mon_submit_error(struct usb_bus *ubus, struct urb *urb, int error)
+static void mon_bus_submit_error(struct mon_bus *mbus, struct urb *urb, int error)
 {
-        struct mon_bus *mbus;
         unsigned long flags;
         struct list_head *pos;
         struct mon_reader *r;
 
-        mbus = ubus->mon_bus;
-        if (mbus == NULL)
-                goto out_unlocked;
-
         spin_lock_irqsave(&mbus->lock, flags);
-        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_error(r->r_data, urb, error);
         }
-
         spin_unlock_irqrestore(&mbus->lock, flags);
         return;
+}
 
-out_locked:
-        spin_unlock_irqrestore(&mbus->lock, flags);
-out_unlocked:
-        return;
+static void mon_submit_error(struct usb_bus *ubus, struct urb *urb, int error)
+{
+        struct mon_bus *mbus;
+
+        if ((mbus = ubus->mon_bus) != NULL)
+                mon_bus_submit_error(mbus, urb, error);
+        mon_bus_submit_error(&mon_bus0, urb, error);
 }
 
 /*
  */
-static void mon_complete(struct usb_bus *ubus, struct urb *urb)
+static void mon_bus_complete(struct mon_bus *mbus, struct urb *urb)
 {
-        struct mon_bus *mbus;
         unsigned long flags;
         struct list_head *pos;
         struct mon_reader *r;
 
+        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);
+        }
+        spin_unlock_irqrestore(&mbus->lock, flags);
+}
+
+static void mon_complete(struct usb_bus *ubus, struct urb *urb)
+{
+        struct mon_bus *mbus;
+
         mbus = ubus->mon_bus;
         if (mbus == NULL) {
                 /*
@@ -162,13 +160,8 @@ static void mon_complete(struct usb_bus *ubus, struct urb *urb)
                 return;
         }
 
-        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);
-        }
-        spin_unlock_irqrestore(&mbus->lock, flags);
+        mon_bus_complete(mbus, urb);
+        mon_bus_complete(&mon_bus0, urb);
 }
 
 /* int (*unlink_urb) (struct urb *urb, int status); */
@@ -179,14 +172,26 @@ static void mon_complete(struct usb_bus *ubus, struct urb *urb)
 static void mon_stop(struct mon_bus *mbus)
 {
         struct usb_bus *ubus = mbus->u_bus;
+        struct list_head *p;
 
-        /*
-         * A stop can be called for a dissolved mon_bus in case of
-         * a reader staying across an rmmod foo_hcd.
-         */
-        if (ubus != NULL) {
-                ubus->monitored = 0;
-                mb();
+        if (mbus == &mon_bus0) {
+                list_for_each (p, &mon_buses) {
+                        mbus = list_entry(p, struct mon_bus, bus_link);
+                        /*
+                         * We do not change nreaders here, so rely on mon_lock.
+                         */
+                        if (mbus->nreaders == 0 && (ubus = mbus->u_bus) != NULL)
+                                ubus->monitored = 0;
+                }
+        } else {
+                /*
+                 * A stop can be called for a dissolved mon_bus in case of
+                 * a reader staying across an rmmod foo_hcd, so test ->u_bus.
+                 */
+                if (mon_bus0.nreaders == 0 && (ubus = mbus->u_bus) != NULL) {
+                        ubus->monitored = 0;
+                        mb();
+                }
         }
 }
 
@@ -199,6 +204,10 @@ static void mon_stop(struct mon_bus *mbus)
 static void mon_bus_add(struct usb_bus *ubus)
 {
         mon_bus_init(ubus);
+        mutex_lock(&mon_lock);
+        if (mon_bus0.nreaders != 0)
+                ubus->monitored = 1;
+        mutex_unlock(&mon_lock);
 }
 
 /*
@@ -250,12 +259,7 @@ static struct usb_mon_operations mon_ops_0 = {
 static void mon_dissolve(struct mon_bus *mbus, struct usb_bus *ubus)
 {
 
-        /*
-         * Never happens, but...
-         */
         if (ubus->monitored) {
-                printk(KERN_ERR TAG ": bus %d is dissolved while monitored\n",
-                    ubus->busnum);
                 ubus->monitored = 0;
                 mb();
         }
@@ -263,6 +267,8 @@ static void mon_dissolve(struct mon_bus *mbus, struct usb_bus *ubus)
         ubus->mon_bus = NULL;
         mbus->u_bus = NULL;
         mb();
+
+        /* We want synchronize_irq() here, but that needs an argument. */
 }
 
 /*
@@ -295,9 +301,8 @@ static void mon_bus_init(struct usb_bus *ubus)
          */
         mbus->u_bus = ubus;
         ubus->mon_bus = mbus;
-        mbus->uses_dma = ubus->uses_dma;
 
-        mbus->text_inited = mon_text_add(mbus, ubus);
+        mbus->text_inited = mon_text_add(mbus, ubus->busnum);
         // mon_bin_add(...)
 
         mutex_lock(&mon_lock);
@@ -309,6 +314,18 @@ err_alloc:
         return;
 }
 
+static void mon_bus0_init(void)
+{
+        struct mon_bus *mbus = &mon_bus0;
+
+        kref_init(&mbus->ref);
+        spin_lock_init(&mbus->lock);
+        INIT_LIST_HEAD(&mbus->r_list);
+
+        mbus->text_inited = mon_text_add(mbus, 0);
+        // mbus->bin_inited = mon_bin_add(mbus, 0);
+}
+
 /*
  * Search a USB bus by number. Notice that USB bus numbers start from one,
  * which we may later use to identify "all" with zero.
@@ -322,6 +339,9 @@ struct mon_bus *mon_bus_lookup(unsigned int num)
         struct list_head *p;
         struct mon_bus *mbus;
 
+        if (num == 0) {
+                return &mon_bus0;
+        }
         list_for_each (p, &mon_buses) {
                 mbus = list_entry(p, struct mon_bus, bus_link);
                 if (mbus->u_bus->busnum == num) {
@@ -341,6 +361,8 @@ static int __init mon_init(void)
         if ((rc = mon_bin_init()) != 0)
                 goto err_bin;
 
+        mon_bus0_init();
+
         if (usb_mon_register(&mon_ops_0) != 0) {
                 printk(KERN_NOTICE TAG ": unable to register with the core\n");
                 rc = -ENODEV;
@@ -374,6 +396,7 @@ static void __exit mon_exit(void)
         usb_mon_deregister();
 
         mutex_lock(&mon_lock);
+
         while (!list_empty(&mon_buses)) {
                 p = mon_buses.next;
                 mbus = list_entry(p, struct mon_bus, bus_link);
@@ -397,6 +420,11 @@ static void __exit mon_exit(void)
                 mon_dissolve(mbus, mbus->u_bus);
                 kref_put(&mbus->ref, mon_bus_drop);
         }
+
+        mbus = &mon_bus0;
+        if (mbus->text_inited)
+                mon_text_del(mbus);
+
         mutex_unlock(&mon_lock);
 
         mon_text_exit();
diff --git a/drivers/usb/mon/mon_text.c b/drivers/usb/mon/mon_text.c
index bbf54396e5f2..ec0cc51e39ac 100644
--- a/drivers/usb/mon/mon_text.c
+++ b/drivers/usb/mon/mon_text.c
@@ -124,8 +124,10 @@ static inline char mon_text_get_setup(struct mon_event_text *ep,
         if (!usb_pipecontrol(urb->pipe) || ev_type != 'S')
                 return '-';
 
-        if (mbus->uses_dma && (urb->transfer_flags & URB_NO_SETUP_DMA_MAP))
+        if (urb->dev->bus->uses_dma &&
+            (urb->transfer_flags & URB_NO_SETUP_DMA_MAP)) {
                 return mon_dmapeek(ep->setup, urb->setup_dma, SETUP_MAX);
+        }
         if (urb->setup_packet == NULL)
                 return 'Z';     /* '0' would be not as pretty. */
 
@@ -160,8 +162,10 @@ static inline char mon_text_get_data(struct mon_event_text *ep, struct urb *urb,
          * contain non-NULL garbage in case the upper level promised to
          * set DMA for the HCD.
          */
-        if (mbus->uses_dma && (urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP))
+        if (urb->dev->bus->uses_dma &&
+            (urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)) {
                 return mon_dmapeek(ep->data, urb->transfer_dma, len);
+        }
 
         if (urb->transfer_buffer == NULL)
                 return 'Z';     /* '0' would be not as pretty. */
@@ -201,7 +205,7 @@ static void mon_text_event(struct mon_reader_text *rp, struct urb *urb,
         ep->type = ev_type;
         ep->pipe = urb->pipe;
         ep->id = (unsigned long) urb;
-        ep->busnum = rp->r.m_bus->u_bus->busnum;
+        ep->busnum = urb->dev->bus->busnum;
         ep->tstamp = stamp;
         ep->length = (ev_type == 'S') ?
             urb->transfer_buffer_length : urb->actual_length;
@@ -305,13 +309,11 @@ static struct mon_event_text *mon_text_fetch(struct mon_reader_text *rp,
 static int mon_text_open(struct inode *inode, struct file *file)
 {
         struct mon_bus *mbus;
-        struct usb_bus *ubus;
         struct mon_reader_text *rp;
         int rc;
 
         mutex_lock(&mon_lock);
         mbus = inode->i_private;
-        ubus = mbus->u_bus;
 
         rp = kzalloc(sizeof(struct mon_reader_text), GFP_KERNEL);
         if (rp == NULL) {
@@ -335,8 +337,7 @@ static int mon_text_open(struct inode *inode, struct file *file)
         rp->r.rnf_error = mon_text_error;
         rp->r.rnf_complete = mon_text_complete;
 
-        snprintf(rp->slab_name, SLAB_NAME_SZ, "mon%dt_%lx", ubus->busnum,
-            (long)rp);
+        snprintf(rp->slab_name, SLAB_NAME_SZ, "mon_text_%p", rp);
         rp->e_slab = kmem_cache_create(rp->slab_name,
             sizeof(struct mon_event_text), sizeof(long), 0,
             mon_text_ctor, NULL);
@@ -654,14 +655,14 @@ static const struct file_operations mon_fops_text_u = {
         .release =      mon_text_release,
 };
 
-int mon_text_add(struct mon_bus *mbus, const struct usb_bus *ubus)
+int mon_text_add(struct mon_bus *mbus, int busnum)
 {
         struct dentry *d;
         enum { NAMESZ = 10 };
         char name[NAMESZ];
         int rc;
 
-        rc = snprintf(name, NAMESZ, "%dt", ubus->busnum);
+        rc = snprintf(name, NAMESZ, "%dt", busnum);
         if (rc <= 0 || rc >= NAMESZ)
                 goto err_print_t;
         d = debugfs_create_file(name, 0600, mon_dir, mbus, &mon_fops_text_t);
@@ -669,7 +670,7 @@ int mon_text_add(struct mon_bus *mbus, const struct usb_bus *ubus)
                 goto err_create_t;
         mbus->dent_t = d;
 
-        rc = snprintf(name, NAMESZ, "%du", ubus->busnum);
+        rc = snprintf(name, NAMESZ, "%du", busnum);
         if (rc <= 0 || rc >= NAMESZ)
                 goto err_print_u;
         d = debugfs_create_file(name, 0600, mon_dir, mbus, &mon_fops_text_u);
@@ -677,7 +678,7 @@ int mon_text_add(struct mon_bus *mbus, const struct usb_bus *ubus)
                 goto err_create_u;
         mbus->dent_u = d;
 
-        rc = snprintf(name, NAMESZ, "%ds", ubus->busnum);
+        rc = snprintf(name, NAMESZ, "%ds", busnum);
         if (rc <= 0 || rc >= NAMESZ)
                 goto err_print_s;
         d = debugfs_create_file(name, 0600, mon_dir, mbus, &mon_fops_stat);
diff --git a/drivers/usb/mon/usb_mon.h b/drivers/usb/mon/usb_mon.h
index a1e2b8e9d777..13d63255283e 100644
--- a/drivers/usb/mon/usb_mon.h
+++ b/drivers/usb/mon/usb_mon.h
@@ -23,7 +23,6 @@ struct mon_bus {
         struct dentry *dent_s;          /* Debugging file */
         struct dentry *dent_t;          /* Text interface file */
         struct dentry *dent_u;          /* Second text interface file */
-        int uses_dma;
 
         /* Ref */
         int nreaders;                   /* Under mon_lock AND mbus->lock */
@@ -53,7 +52,7 @@ 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);
+int /*bool*/ mon_text_add(struct mon_bus *mbus, int busnum);
 void mon_text_del(struct mon_bus *mbus);
 // void mon_bin_add(struct mon_bus *);
 
@@ -82,4 +81,6 @@ 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 */