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Re: [PATCH v2 2/2] arm: perf: Mark as non-removable

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On Wed, Jan 04, 2017 at 11:30:25AM +0000, Mark Rutland wrote:
> On Wed, Jan 04, 2017 at 10:19:46AM +0100, Alexander Stein wrote:
> > I'm not sure if the change above works with remove functions set in struct 
> > bus_type too.
> > But on the other hand this would hide errors in drivers which are actually 
> > removable but do not cleanup properly which DEBUG_TEST_DRIVER_REMOVE tries to 
> > detect.
> > By setting .suppress_bind_attrs = true explicitely you state "This 
> > driver cannot be removed!", so the remove callback is not missing by accident.
> 
> I'm not sure I follow. If the remove callback is accidentally missing,
> the driver is not "actually removable" today -- there's either no remove
> code, or it's not been wired up (the latter of which will likely result
> in a compiler warning about an unused function).
> 
> Aborting the remove early in those cases is much safer than forcefully
> removing a driver without a remove callback.

Drivers without a remove function may be removable - there's more layers
than just the driver - there's the bus layer as well, which may or may
not direct to a private-bus pointer.

There's no real way for the core driver model code to know whether the
lack of the ->remove in the struct device_driver is something that
prevents a driver being removed, or whether it's handled via some other
method.  Eg, platform drivers.

-- 
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Re: [PATCH v2 2/2] arm: perf: Mark as non-removable Alexander Stein <alexander.stein@systec-electronic.com> - 2017-01-04 10:30 +0100
  Re: [PATCH v2 2/2] arm: perf: Mark as non-removable Mark Rutland <mark.rutland@arm.com> - 2017-01-04 12:40 +0100
    Re: [PATCH v2 2/2] arm: perf: Mark as non-removable Russell King - ARM Linux <linux@armlinux.org.uk> - 2017-01-04 12:50 +0100
      Re: [PATCH v2 2/2] arm: perf: Mark as non-removable Mark Rutland <mark.rutland@arm.com> - 2017-01-04 12:50 +0100
        Re: [PATCH v2 2/2] arm: perf: Mark as non-removable Will Deacon <will.deacon@arm.com> - 2017-01-04 19:30 +0100

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