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kay.sievers@vrfy.org a8b5267a62 [PATCH] finally solve the bad sysfs-timing for all of us
On Tue, Sep 21, 2004 at 07:17:34PM +0200, Kay Sievers wrote:
> During the integration of HAL into the linux hotplug system, we dicover
> every week a new signaling path that fails cause of the delayed
> population of the sysfs files, which are connected by symlinks and
> appear in something like a random order in userspace.
>
> It's pretty complicated to understand the connection between all these
> files for all the different subsystems with all the exceptions, so most
> of the users simply sleep a few seconds, but that is not acceptable for
> our integration work.
>
> Here I try to get all the special knowledge about that behavior together
> and place that in a simple binary. That program _must_ run first of all
> other hotplug processsing and every later script, udev or HAL all can get
> rid of the wild guesses about the right time sysfs is ready.
>
> It will not only wait for the "dev"-file events we handle with udev, also
> for every /device-device with the corresponding bus link.
>
> It is provided as a patch against the current udev tree and a "install" will
> place the new program in the hotplug.d directory:
>
>   [kay@pim ~]$ tree /etc/hotplug.d/
>   /etc/hotplug.d/
>   `-- default
>       |-- 00-wait_for_sysfs.hotplug -> /sbin/wait_for_sysfs
>       |-- 10-udev.hotplug -> /sbin/udevsend
>       |-- 20-hal.hotplug -> /usr/libexec/hal.hotplug
>       |-- default.hotplug
>       `-- log.hotplug
>
>
> For now, it logs the result of the waiting to syslog, to catch any
> device, that needs special treatment. All newly discovered delay problems,
> device black/whitelist updates should go into that program and we may remove
> that kind of specialisation from all the other hotplug programs.
>
> Any patches, reports, testing is more than welcome.
>
> Sample debug:
>   Sep 21 18:44:07 localhost kernel: usb 3-2: new full speed USB device using address 12
>   Sep 21 18:44:07 localhost kernel: hub 3-2:1.0: USB hub found
>   Sep 21 18:44:07 localhost kernel: hub 3-2:1.0: 2 ports detected
>   Sep 21 18:44:07 localhost 00-wait_for_sysfs.hotplug: result: waiting for sysfs successful '/devices/pci0000:00/0000:00:1d.1/usb3/3-2'
>   Sep 21 18:44:07 localhost 00-wait_for_sysfs.hotplug: result: waiting for sysfs successful '/devices/pci0000:00/0000:00:1d.1/usb3/3-2/3-2:1.0'
>   Sep 21 18:44:08 localhost kernel: usb 3-2.1: new full speed USB device using address 13
>   Sep 21 18:44:08 localhost 00-wait_for_sysfs.hotplug: result: waiting for sysfs successful '/class/usb/lp0'
>   Sep 21 18:44:08 localhost kernel: drivers/usb/class/usblp.c: usblp0: USB Bidirectional printer dev 13 if 0 alt 1 proto 2 vid 0x067B pid 0x2305
>   Sep 21 18:44:08 localhost 00-wait_for_sysfs.hotplug: result: waiting for sysfs successful '/devices/pci0000:00/0000:00:1d.1/usb3/3-2/3-2.1/3-2.1:1.0'
>   Sep 21 18:44:08 localhost 00-wait_for_sysfs.hotplug: result: waiting for sysfs successful '/devices/pci0000:00/0000:00:1d.1/usb3/3-2/3-2.1'
>   Sep 21 18:44:08 localhost udev: configured rule in '/etc/udev/rules.d/50-udev.rules' at line 29 applied, 'lp0' becomes 'usb/%k'
>   Sep 21 18:44:08 localhost udev: creating device node '/udev/usb/lp0'
>   Sep 21 18:44:09 localhost kernel: usb 3-2.2: new full speed USB device using address 14
>   Sep 21 18:44:09 localhost kernel: pl2303 3-2.2:1.0: PL-2303 converter detected
>   Sep 21 18:44:09 localhost kernel: usb 3-2.2: PL-2303 converter now attached to ttyUSB0
>   Sep 21 18:44:09 localhost 00-wait_for_sysfs.hotplug: result: waiting for sysfs successful '/devices/pci0000:00/0000:00:1d.1/usb3/3-2/3-2.2'
>   Sep 21 18:44:09 localhost 00-wait_for_sysfs.hotplug: result: waiting for sysfs successful '/devices/pci0000:00/0000:00:1d.1/usb3/3-2/3-2.2/3-2.2:1.0'
>   Sep 21 18:44:09 localhost 00-wait_for_sysfs.hotplug: result: waiting for sysfs successful '/devices/pci0000:00/0000:00:1d.1/usb3/3-2/3-2.2/3-2.2:1.0/ttyUSB0'
>   Sep 21 18:44:09 localhost 00-wait_for_sysfs.hotplug: result: waiting for sysfs successful '/class/tty/ttyUSB0'
>   Sep 21 18:44:09 localhost udev: creating device node '/udev/ttyUSB0'

New version with more devices excluded from /device-link saerch and
a better maching for device names.
2005-04-26 21:37:02 -07:00
docs [PATCH] Writing udev rules doc update 2005-04-26 21:36:21 -07:00
etc [PATCH] add symlink for video rule. 2005-04-26 21:37:00 -07:00
extras [PATCH] update udev to include scsi_id 0.6 2005-04-26 21:37:02 -07:00
klibc [PATCH] fix up Makefiles to get the klibc build working properly. 2005-04-26 21:37:02 -07:00
libsysfs [PATCH] udevd race conditions and performance, assorted cleanups - take 2 2005-04-26 21:35:13 -07:00
tdb [PATCH] make spotless 2005-04-26 21:35:10 -07:00
test [PATCH] add enum tests 2005-04-26 21:37:01 -07:00
ChangeLog [PATCH] 032 release 2005-04-26 21:37:00 -07:00
COPYING [PATCH] added initial documentation and gpl license 2005-04-26 21:00:32 -07:00
dev_d.c [PATCH] Make udev/udevstart be one binary 2005-04-26 21:36:59 -07:00
FAQ [PATCH] Update the FAQ with info about hardlink security 2005-04-26 21:36:59 -07:00
HOWTO-udev_for_dev [PATCH] fix HOWTO-udev_for_dev for udevdir 2005-04-26 21:35:10 -07:00
klibc_fixups.c [PATCH] udev - read long lines from config files overflow fix 2005-04-26 21:37:00 -07:00
klibc_fixups.h [PATCH] catchup with recent klibc 2005-04-26 21:35:47 -07:00
list.h [PATCH] Initial namedev parsing of config files 2005-04-26 21:01:38 -07:00
logging.h [PATCH] overall trivial trivial cleanup 2005-04-26 21:35:08 -07:00
make_gcov.sh [PATCH] add scripts to run gcov for udev from Leann Ogasawara <ogasawara@osdl.org> 2005-04-26 21:35:15 -07:00
Makefile [PATCH] finally solve the bad sysfs-timing for all of us 2005-04-26 21:37:02 -07:00
namedev_parse.c [PATCH] fix udev segfaults with bad permissions file 2005-04-26 21:37:01 -07:00
namedev.c [PATCH] udev parse bug 2005-04-26 21:37:00 -07:00
namedev.h [PATCH] dev_d.c file sorting and cleanup 2005-04-26 21:35:12 -07:00
README [PATCH] remove USE_DBUS and USE_SELINUX flags from the README as they are no longer present. 2005-04-26 21:35:11 -07:00
README-gcov_for_udev [PATCH] gcov for udev 2005-04-26 21:35:16 -07:00
run_gcov.sh [PATCH] add scripts to run gcov for udev from Leann Ogasawara <ogasawara@osdl.org> 2005-04-26 21:35:15 -07:00
TODO [PATCH] update the TODO list as we already have a devfs config file. 2005-04-26 21:35:07 -07:00
udev_config.c [PATCH] fix udev segfaults with bad permissions file 2005-04-26 21:37:01 -07:00
udev_lib.c [PATCH] fix handle leak in udev_lib.c 2005-04-26 21:35:47 -07:00
udev_lib.h [PATCH] switch udev's seqnum to u64 2005-04-26 21:37:01 -07:00
udev-add.c [PATCH] Make udev/udevstart be one binary 2005-04-26 21:36:59 -07:00
udev-remove.c [PATCH] Make udev/udevstart be one binary 2005-04-26 21:36:59 -07:00
udev.8.in [PATCH] compatibility symlinks for udev 2005-04-26 21:37:00 -07:00
udev.c [PATCH] handle only block and class devices 2005-04-26 21:37:00 -07:00
udev.h [PATCH] switch udev's seqnum to u64 2005-04-26 21:37:01 -07:00
udev.spec [PATCH] 032 release 2005-04-26 21:37:00 -07:00
udevd.8 [PATCH] fix manpages based on esr's spambot 2005-04-26 21:36:59 -07:00
udevd.c [PATCH] switch udev's seqnum to u64 2005-04-26 21:37:01 -07:00
udevd.h [PATCH] switch udev's seqnum to u64 2005-04-26 21:37:01 -07:00
udevdb.c [PATCH] allow NAME_SIZE > SYSFS_PATH_MAX 2005-04-26 21:36:59 -07:00
udevdb.h [PATCH] udev - reverse user query options 2005-04-26 21:13:17 -07:00
udevinfo.8 [PATCH] update bk ignore list some more. 2005-04-26 21:35:14 -07:00
udevinfo.c [PATCH] netdev - udevdb+dev.d changes 2005-04-26 21:35:13 -07:00
udevruler.c [PATCH] handle netdev in udevruler 2005-04-26 21:35:14 -07:00
udevsend.c [PATCH] switch udev's seqnum to u64 2005-04-26 21:37:01 -07:00
udevstart.8 [PATCH] update bk ignore list some more. 2005-04-26 21:35:14 -07:00
udevstart.c [PATCH] add a "first" list to udevstart and make it contain the class/mem/ devices 2005-04-26 21:37:00 -07:00
udevtest.8 [PATCH] update bk ignore list some more. 2005-04-26 21:35:14 -07:00
udevtest.c [PATCH] fix compiler warning in udevtest.c 2005-04-26 21:37:00 -07:00
wait_for_sysfs.c [PATCH] finally solve the bad sysfs-timing for all of us 2005-04-26 21:37:02 -07:00

udev - a userspace implementation of devfs

For more information on the design, and structure of this project, see the
files in the docs/ directory.

To use:

- You must be running a 2.6 version of the Linux kernel.

- Your 2.6 kernel must have had CONFIG_HOTPLUG enabled when it was built.

- Make sure sysfs is mounted.  udev will figure out where sysfs is mounted, but
  the traditional place for it is at /sys.  You can mount it by hand by running:
  	mount -t sysfs none /sys

- Make sure you have the latest version of the linux-hotplug scripts.  They are
  available at linux-hotplug.sf.net or from your local kernel.org mirror at:
	kernel.org/pub/linux/utils/kernel/hotplug/
  They are required in order for udev to work properly.

  If for some reason you do not install the hotplug scripts, you must tell the
  kernel to point the hotplug binary at wherever you install udev at.  This can
  be done by:
	echo "/sbin/udev" > /proc/sys/kernel/hotplug

- Build the project:
	make

  Note:
      There are a number of different flags that you can use when building
      udev.  They are as follows:
	prefix
		set this to the default root that you want udev to be
		installed into.  This works just like the 'configure --prefix'
		script does.  Default value is ''.  Only override this if you
		really know what you are doing.
	USE_KLIBC
		if set to 'true', udev is built and linked against the
		included version of klibc.  Default value is 'false'.
	USE_LOG
		if set to 'true', udev will emit messages to the syslog when
		it creates or removes device nodes.  This is helpful to see
		what udev is doing.  This is enabled by default.  Note, if you
		are building udev against klibc it is recommended that you
		disable this option (due to klibc's syslog implementation.)
	DEBUG
		if set to 'true', debugging messages will be sent to the syslog
		as udev is run.  Default value is 'false'.
	KERNEL_DIR
		If this is not set it will default to /lib/modules/`uname -r`/build
		This is used if USE_KLIBC=true to find the kernel include
		directory that klibc needs to build against.  This must be set
		if you are not building udev while running a 2.6 kernel.

      So, if you want to build udev using klibc with debugging messages, you
      would do:
	make USE_KLIBC=true DEBUG=true

- Install the project:
	make install

  This will put the udev binary in /sbin, create the /udev and /etc/udev
  directories, and place the udev configuration files in /etc/udev.  You
  will probably want to edit the namedev.* files to create custom naming
  rules.  More info on how the config files are set up are contained in
  comments in the files, and is located in the documentation.

- Add and remove devices from the system and marvel as nodes are created
  and removed in /udev/ based on the device types.

- If you later get sick of it, uninstall it:
	make uninstall


Things are still quite rough, but it should work properly.  If nothing
seems to happen, make sure your build worked properly by running the
udev-test.pl script as root in the test/ subdirectory of the udev source
tree.

Development and documentation help is very much appreciated, see the TODO
file for a list of things left to be done.


Any comment/questions/concerns please let me and the other udev developers
know by sending a message to the linux-hotplug-devel mailing list at:
	linux-hotplug-devel@lists.sourceforge.net

greg k-h
greg@kroah.com