* Re: udev PROGRAM key and the device chain walk
2005-02-13 14:15 udev PROGRAM key and the device chain walk Kay Sievers
@ 2005-02-14 19:19 ` Greg KH
2005-02-15 0:55 ` Kay Sievers
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Greg KH @ 2005-02-14 19:19 UTC (permalink / raw)
To: linux-hotplug
On Sun, Feb 13, 2005 at 03:15:25PM +0100, Kay Sievers wrote:
> While we try to match rule keys against a devices sysfs representaion,
> we need to follow the physical device and walk up the device chain up to
> the root device and match our rule against every device found.
>
> While this is necessary to match the SYSFS and BUS keys, it has the
> _very_ bad side effect, that a PROGRAM may be executed several times. In
> my test setup, I've seen five executions of a callout to match one single
> rule.
Is this because the rule was written badly?
> The only reason to do this, is the match with a callout against a sysfs
> attribute of one of the physical devices along the chain by using
> the %s{<attr>} key.
> I don't think that this is really needed and I want to change the namedev
> logic to execute the PROGRAM key only once per rule. It will be still
> possible to pass the %s{<attr>} to the callout, but it will only happen
> at the device itself and not follow the chain to the root device. If
> such a thing is ever needed, the callout can do it itself and not rely on
> udev to execute it several times.
>
> Any objections, or I will change that to speed things up.
Again, is this really needed, or do we just blame it on a badly written
rule?
thanks,
greg k-h
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: udev PROGRAM key and the device chain walk
2005-02-13 14:15 udev PROGRAM key and the device chain walk Kay Sievers
2005-02-14 19:19 ` Greg KH
@ 2005-02-15 0:55 ` Kay Sievers
2005-02-15 1:07 ` Greg KH
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Kay Sievers @ 2005-02-15 0:55 UTC (permalink / raw)
To: linux-hotplug
On Mon, Feb 14, 2005 at 11:19:09AM -0800, Greg KH wrote:
> On Sun, Feb 13, 2005 at 03:15:25PM +0100, Kay Sievers wrote:
> > While we try to match rule keys against a devices sysfs representaion,
> > we need to follow the physical device and walk up the device chain up to
> > the root device and match our rule against every device found.
> >
> > While this is necessary to match the SYSFS and BUS keys, it has the
> > _very_ bad side effect, that a PROGRAM may be executed several times. In
> > my test setup, I've seen five executions of a callout to match one single
> > rule.
>
> Is this because the rule was written badly?
>
> > The only reason to do this, is the match with a callout against a sysfs
> > attribute of one of the physical devices along the chain by using
> > the %s{<attr>} key.
> > I don't think that this is really needed and I want to change the namedev
> > logic to execute the PROGRAM key only once per rule. It will be still
> > possible to pass the %s{<attr>} to the callout, but it will only happen
> > at the device itself and not follow the chain to the root device. If
> > such a thing is ever needed, the callout can do it itself and not rely on
> > udev to execute it several times.
> >
> > Any objections, or I will change that to speed things up.
>
> Again, is this really needed, or do we just blame it on a badly written
> rule?
I wouldn't call it badly written. If the PROGRAM execution returns
nonzero, namedev may execute the program again for every device in /sys/devices.
That is pretty useless as the parameters for the execution are the same for
every call, except you pass %s{sysfsfile} to it.
And yeah, a rule which passes a %s{sysfsfile} content from a device somewhere
in the physical device chain is a "badly" written rule. :)
I think we should fix that.
Thanks,
Kay
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: udev PROGRAM key and the device chain walk
2005-02-13 14:15 udev PROGRAM key and the device chain walk Kay Sievers
2005-02-14 19:19 ` Greg KH
2005-02-15 0:55 ` Kay Sievers
@ 2005-02-15 1:07 ` Greg KH
2005-02-15 1:47 ` Kay Sievers
2005-02-15 23:52 ` Greg KH
4 siblings, 0 replies; 6+ messages in thread
From: Greg KH @ 2005-02-15 1:07 UTC (permalink / raw)
To: linux-hotplug
On Tue, Feb 15, 2005 at 01:55:47AM +0100, Kay Sievers wrote:
> On Mon, Feb 14, 2005 at 11:19:09AM -0800, Greg KH wrote:
> > On Sun, Feb 13, 2005 at 03:15:25PM +0100, Kay Sievers wrote:
> > > While we try to match rule keys against a devices sysfs representaion,
> > > we need to follow the physical device and walk up the device chain up to
> > > the root device and match our rule against every device found.
> > >
> > > While this is necessary to match the SYSFS and BUS keys, it has the
> > > _very_ bad side effect, that a PROGRAM may be executed several times. In
> > > my test setup, I've seen five executions of a callout to match one single
> > > rule.
> >
> > Is this because the rule was written badly?
> >
> > > The only reason to do this, is the match with a callout against a sysfs
> > > attribute of one of the physical devices along the chain by using
> > > the %s{<attr>} key.
> > > I don't think that this is really needed and I want to change the namedev
> > > logic to execute the PROGRAM key only once per rule. It will be still
> > > possible to pass the %s{<attr>} to the callout, but it will only happen
> > > at the device itself and not follow the chain to the root device. If
> > > such a thing is ever needed, the callout can do it itself and not rely on
> > > udev to execute it several times.
> > >
> > > Any objections, or I will change that to speed things up.
> >
> > Again, is this really needed, or do we just blame it on a badly written
> > rule?
>
> I wouldn't call it badly written. If the PROGRAM execution returns
> nonzero, namedev may execute the program again for every device in /sys/devices.
> That is pretty useless as the parameters for the execution are the same for
> every call, except you pass %s{sysfsfile} to it.
Ok, I mean we shouldn't have a rule that is only PROGRAM. It should
have something else in it, like BUS, or SUBSYSTEM, or a sysfs file match
to prevent this from happening, right?
> And yeah, a rule which passes a %s{sysfsfile} content from a device somewhere
> in the physical device chain is a "badly" written rule. :)
You mean as a paramater? Heh, that seems like a fun hack to make the
external program logic simpler :)
I don't think we should break that, do you?
thanks,
greg k-h
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: udev PROGRAM key and the device chain walk
2005-02-13 14:15 udev PROGRAM key and the device chain walk Kay Sievers
` (2 preceding siblings ...)
2005-02-15 1:07 ` Greg KH
@ 2005-02-15 1:47 ` Kay Sievers
2005-02-15 23:52 ` Greg KH
4 siblings, 0 replies; 6+ messages in thread
From: Kay Sievers @ 2005-02-15 1:47 UTC (permalink / raw)
To: linux-hotplug
On Mon, Feb 14, 2005 at 05:07:33PM -0800, Greg KH wrote:
> On Tue, Feb 15, 2005 at 01:55:47AM +0100, Kay Sievers wrote:
> > On Mon, Feb 14, 2005 at 11:19:09AM -0800, Greg KH wrote:
> > > On Sun, Feb 13, 2005 at 03:15:25PM +0100, Kay Sievers wrote:
> > > > While we try to match rule keys against a devices sysfs representaion,
> > > > we need to follow the physical device and walk up the device chain up to
> > > > the root device and match our rule against every device found.
> > > >
> > > > While this is necessary to match the SYSFS and BUS keys, it has the
> > > > _very_ bad side effect, that a PROGRAM may be executed several times. In
> > > > my test setup, I've seen five executions of a callout to match one single
> > > > rule.
> > >
> > > Is this because the rule was written badly?
> > >
> > > > The only reason to do this, is the match with a callout against a sysfs
> > > > attribute of one of the physical devices along the chain by using
> > > > the %s{<attr>} key.
> > > > I don't think that this is really needed and I want to change the namedev
> > > > logic to execute the PROGRAM key only once per rule. It will be still
> > > > possible to pass the %s{<attr>} to the callout, but it will only happen
> > > > at the device itself and not follow the chain to the root device. If
> > > > such a thing is ever needed, the callout can do it itself and not rely on
> > > > udev to execute it several times.
> > > >
> > > > Any objections, or I will change that to speed things up.
> > >
> > > Again, is this really needed, or do we just blame it on a badly written
> > > rule?
> >
> > I wouldn't call it badly written. If the PROGRAM execution returns
> > nonzero, namedev may execute the program again for every device in /sys/devices.
> > That is pretty useless as the parameters for the execution are the same for
> > every call, except you pass %s{sysfsfile} to it.
>
> Ok, I mean we shouldn't have a rule that is only PROGRAM. It should
> have something else in it, like BUS, or SUBSYSTEM, or a sysfs file match
> to prevent this from happening, right?
Sure, and fortunately most of them are doing so. I just want to fix the behavior if
these keys are _not_ given. If one of these keys is present, nothing changes!
> > And yeah, a rule which passes a %s{sysfsfile} content from a device somewhere
> > in the physical device chain is a "badly" written rule. :)
>
> You mean as a paramater? Heh, that seems like a fun hack to make the
> external program logic simpler :)
>
> I don't think we should break that, do you?
No, sure, this will still work as expected. But not for an arbitrary device
in the physical devices path which sounds crazy anyway. :)
To turn around the question: What functionality do you want to keep here?
A rule with only the PROGRAM key, which walks up the physical devices path
and executes the program multiple times and doesn't stop on nonzero exit?
Thanks,
Kay
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: udev PROGRAM key and the device chain walk
2005-02-13 14:15 udev PROGRAM key and the device chain walk Kay Sievers
` (3 preceding siblings ...)
2005-02-15 1:47 ` Kay Sievers
@ 2005-02-15 23:52 ` Greg KH
4 siblings, 0 replies; 6+ messages in thread
From: Greg KH @ 2005-02-15 23:52 UTC (permalink / raw)
To: linux-hotplug
On Tue, Feb 15, 2005 at 02:47:43AM +0100, Kay Sievers wrote:
> On Mon, Feb 14, 2005 at 05:07:33PM -0800, Greg KH wrote:
> > On Tue, Feb 15, 2005 at 01:55:47AM +0100, Kay Sievers wrote:
> > > On Mon, Feb 14, 2005 at 11:19:09AM -0800, Greg KH wrote:
> > > > On Sun, Feb 13, 2005 at 03:15:25PM +0100, Kay Sievers wrote:
> > > > > While we try to match rule keys against a devices sysfs representaion,
> > > > > we need to follow the physical device and walk up the device chain up to
> > > > > the root device and match our rule against every device found.
> > > > >
> > > > > While this is necessary to match the SYSFS and BUS keys, it has the
> > > > > _very_ bad side effect, that a PROGRAM may be executed several times. In
> > > > > my test setup, I've seen five executions of a callout to match one single
> > > > > rule.
> > > >
> > > > Is this because the rule was written badly?
> > > >
> > > > > The only reason to do this, is the match with a callout against a sysfs
> > > > > attribute of one of the physical devices along the chain by using
> > > > > the %s{<attr>} key.
> > > > > I don't think that this is really needed and I want to change the namedev
> > > > > logic to execute the PROGRAM key only once per rule. It will be still
> > > > > possible to pass the %s{<attr>} to the callout, but it will only happen
> > > > > at the device itself and not follow the chain to the root device. If
> > > > > such a thing is ever needed, the callout can do it itself and not rely on
> > > > > udev to execute it several times.
> > > > >
> > > > > Any objections, or I will change that to speed things up.
> > > >
> > > > Again, is this really needed, or do we just blame it on a badly written
> > > > rule?
> > >
> > > I wouldn't call it badly written. If the PROGRAM execution returns
> > > nonzero, namedev may execute the program again for every device in /sys/devices.
> > > That is pretty useless as the parameters for the execution are the same for
> > > every call, except you pass %s{sysfsfile} to it.
> >
> > Ok, I mean we shouldn't have a rule that is only PROGRAM. It should
> > have something else in it, like BUS, or SUBSYSTEM, or a sysfs file match
> > to prevent this from happening, right?
>
> Sure, and fortunately most of them are doing so. I just want to fix the behavior if
> these keys are _not_ given. If one of these keys is present, nothing changes!
>
> > > And yeah, a rule which passes a %s{sysfsfile} content from a device somewhere
> > > in the physical device chain is a "badly" written rule. :)
> >
> > You mean as a paramater? Heh, that seems like a fun hack to make the
> > external program logic simpler :)
> >
> > I don't think we should break that, do you?
>
> No, sure, this will still work as expected. But not for an arbitrary device
> in the physical devices path which sounds crazy anyway. :)
>
> To turn around the question: What functionality do you want to keep here?
> A rule with only the PROGRAM key, which walks up the physical devices path
> and executes the program multiple times and doesn't stop on nonzero exit?
I guess I don't see a real problem here that needs to be fixed. If a
rule is dumb enough to want to run a program on every device in the
chain, let it :)
thanks,
greg k-h
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^ permalink raw reply [flat|nested] 6+ messages in thread