From: Tomohiro Kusumi <kusumi.tomohiro@jp.fujitsu.com>
To: linux-usb@vger.kernel.org, stern@rowland.harvard.edu,
gregkh@suse.de, linux-kernel@vger.kernel.org
Subject: [PATCH] add usb_add_bus() function for usb bus list
Date: Fri, 23 Apr 2010 14:45:45 +0900 [thread overview]
Message-ID: <4BD13409.5040003@jp.fujitsu.com> (raw)
Hi,
This patch makes usbcore driver sort usb bus on the usb_bus_list by busnum when
registering a new bus instance.
In current implementation a new bus instance is simply added in front of existing busses.
Although there is nothing wrong with it in kernel code, reloading HCD may break bus order
of /proc/bus/usb/devices as it makes usbcore re-register the bus to the list as shown in
the example below. and it doesn't look good or it may confuse some users.
# lsmod | grep hcd
uhci_hcd 19324 0
ehci_hcd 39109 0
# grep "Bus=" /proc/bus/usb/devices
T: Bus=05 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2
T: Bus=04 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2
T: Bus=03 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2
T: Bus=02 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2
T: Bus=02 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 2 Spd=1.5 MxCh= 0
T: Bus=02 Lev=01 Prnt=01 Port=01 Cnt=02 Dev#= 3 Spd=12 MxCh= 0
T: Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=480 MxCh= 8
T: Bus=01 Lev=01 Prnt=01 Port=02 Cnt=01 Dev#= 4 Spd=480 MxCh= 4
# rmmod ehci-hcd; modprobe ehci-hcd
# grep "Bus=" /proc/bus/usb/devices
T: Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=480 MxCh= 8
T: Bus=01 Lev=01 Prnt=01 Port=02 Cnt=01 Dev#= 4 Spd=480 MxCh= 4
T: Bus=05 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2
T: Bus=04 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2
T: Bus=03 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2
T: Bus=02 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2
T: Bus=02 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 4 Spd=1.5 MxCh= 0
T: Bus=02 Lev=01 Prnt=01 Port=01 Cnt=02 Dev#= 5 Spd=12 MxCh= 0
With this patch, bus instances on the usb_bus_list is kept in busnum order (from large to
small busnum). As a result /proc/bus/usb/devices prints devices in busnum order regardless
of HCD reloading. Although a few applications (eg.lsusb) use /proc/bus/usb/devices, this
patch has no effect to them.
# lsmod | grep hcd
uhci_hcd 19324 0
ehci_hcd 39109 0
# grep "Bus=" /proc/bus/usb/devices
T: Bus=05 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2
T: Bus=04 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2
T: Bus=03 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2
T: Bus=02 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2
T: Bus=02 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 2 Spd=1.5 MxCh= 0
T: Bus=02 Lev=01 Prnt=01 Port=01 Cnt=02 Dev#= 3 Spd=12 MxCh= 0
T: Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=480 MxCh= 8
T: Bus=01 Lev=01 Prnt=01 Port=02 Cnt=01 Dev#= 4 Spd=480 MxCh= 4
# rmmod ehci-hcd; modprobe ehci-hcd
# grep "Bus=" /proc/bus/usb/devices
T: Bus=05 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2
T: Bus=04 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2
T: Bus=03 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2
T: Bus=02 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2
T: Bus=02 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 4 Spd=1.5 MxCh= 0
T: Bus=02 Lev=01 Prnt=01 Port=01 Cnt=02 Dev#= 5 Spd=12 MxCh= 0
T: Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=480 MxCh= 8
T: Bus=01 Lev=01 Prnt=01 Port=02 Cnt=01 Dev#= 4 Spd=480 MxCh= 4
Thanks,
Tomohiro Kusumi
Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@jp.fujitsu.com>
---
diff -aNur linux-2.6.34-rc5.org/drivers/usb/core/hcd.c linux-2.6.34-rc5/drivers/usb/core/hcd.c
--- linux-2.6.34-rc5.org/drivers/usb/core/hcd.c 2010-04-20 08:29:56.000000000 +0900
+++ linux-2.6.34-rc5/drivers/usb/core/hcd.c 2010-04-23 14:19:50.000000000 +0900
@@ -877,6 +877,23 @@
/*-------------------------------------------------------------------------*/
/**
+ * usb_add_bus - register the bus to the usb_bus_list,
+ * caller need to hold usb_bus_list_lock
+ * @bus: pointer to the bus to register
+ */
+static void usb_add_bus(struct usb_bus *bus)
+{
+ struct usb_bus *b;
+ list_for_each_entry(b, &usb_bus_list, bus_list) {
+ if (bus->busnum > b->busnum) {
+ list_add_tail(&bus->bus_list, &b->bus_list);
+ return;
+ }
+ }
+ list_add_tail(&bus->bus_list, &usb_bus_list);
+}
+
+/**
* usb_register_bus - registers the USB host controller with the usb core
* @bus: pointer to the bus to register
* Context: !in_interrupt()
@@ -899,7 +916,7 @@
bus->busnum = busnum;
/* Add it to the local list of buses */
- list_add (&bus->bus_list, &usb_bus_list);
+ usb_add_bus(bus);
mutex_unlock(&usb_bus_list_lock);
usb_notify_add_bus(bus);
next reply other threads:[~2010-04-23 5:45 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-23 5:45 Tomohiro Kusumi [this message]
2010-04-23 15:03 ` [PATCH] add usb_add_bus() function for usb bus list Greg KH
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4BD13409.5040003@jp.fujitsu.com \
--to=kusumi.tomohiro@jp.fujitsu.com \
--cc=gregkh@suse.de \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-usb@vger.kernel.org \
--cc=stern@rowland.harvard.edu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.