If a device does not have a major/minor number attached, we use different
database names than if it does. On "change" events, we didn't copy the
devnum over, therefore, we used different paths than on 'add' or 'remove'
events (where devnum was properly copied).
Fix this by always copying the devnum into the udev-device.
(David: added commit-log from email)
Creating the rtnl context is cheap, but freeing it may not be, due to
synchronous close().
Also drop some excessive logging. We now log about the changing ifname
exactly once.
Previously the returned object of constructor functions where sometimes
returned as last, sometimes as first and sometimes as second parameter.
Let's clean this up a bit. Here are the new rules:
1. The object the new object is derived from is put first, if there is any
2. The object we are creating will be returned in the next arguments
3. This is followed by any additional arguments
Rationale:
For functions that operate on an object we always put that object first.
Constructors should probably not be too different in this regard. Also,
if the additional parameters might want to use varargs which suggests to
put them last.
Note that this new scheme only applies to constructor functions, not to
all other functions. We do give a lot of freedom for those.
Note that this commit only changes the order of the new functions we
added, for old ones we accept the wrong order and leave it like that.
The "sd_" prefix is supposed to be used on exported symbols only, and
not in the middle of names. Let's drop it from the cleanup macros hence,
to make things simpler.
The bus cleanup macros don't carry the "sd_" either, so this brings the
APIs a bit nearer.
In trying to track down a stupid linker bug, I noticed a bunch of
memset() calls that should be using memzero() to make it more "obvious"
that the options are correct (i.e. 0 is not the length, but the data to
set). So fix up all current calls to memset(foo, 0, length) to
memzero(foo, length).
If a 'change' event is supposed to remove created symlinks, we create
a new device structure from the sysfs device and fill it with the list
of links, to compute the delta of the old and new list of links to apply.
If the device is already 'remove'd by the kernel though, udev fails to
create the device structure, so the links are not removed properly.
> From: Neil Brown <nfbrown@suse.com>
> Date: Thu, 8 Nov 2012 10:39:06 +0100
> Subject: [PATCH] If a 'change' event does not get handled by udev until
> after the device has subsequently disappeared, udev mis-handles
> it. This can happen with 'md' devices which emit a change
> event and then a remove event when they are stopped. It is
> normally only noticed if udev is very busy (lots of arrays
> being stopped at once) or the machine is otherwise loaded
> and reponding slowly.
>
> There are two problems.
>
> 1/ udev_device_new_from_syspath() will refuse to create the device
> structure if the device does not exist in /sys, and particularly if
> the uevent file does not exist.
> If a 'db' file does exist, that is sufficient evidence that the device
> is genuine and should be created. Equally if we have just received an
> event from the kernel about the device, it must be real.
>
> This patch just disabled the test for the 'uevent' file, it doesn't
> try imposing any other tests - it isn't clear that they are really
> needed.
>
> 2/ udev_event_execute_rules() calls udev_device_read_db() on a 'device'
> structure that is largely uninitialised and in particular does not
> have the 'subsystem' set. udev_device_read_db() needs the subsystem
> so it tries to read the 'subsystem' symlink out of sysfs. If the
> device is already deleted, this naturally fails.
> udev_event_execute_rules() knows the subsystem (as it was in the
> event message) so this patch simply sets the subsystem for the device
> structure to be loaded to match the subsystem of the device structure
> that is handling the event.
>
> With these two changes, deleted handling of change events will still
> correctly remove any symlinks that are not needed any more.
Use udev_device_new() instead of allowing udev_device_new_from_syspath()
to proceed without a sysfs device.
