Messages in this thread | | | Date | Wed, 4 Jan 2017 18:17:18 +0000 | From | Will Deacon <> | Subject | Re: [PATCH v2 2/2] arm: perf: Mark as non-removable |
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On Wed, Jan 04, 2017 at 11:46:13AM +0000, Mark Rutland wrote: > On Wed, Jan 04, 2017 at 11:40:56AM +0000, Russell King - ARM Linux wrote: > > 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. > > Sure; which is why I initially suggested doing something at the bus > layer. That way, each layer could do any necessary check, and/or > delegate to a callback for the layer below. > > > 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. > > While true today, my suggestion is to add the infrastrucutre such that > it can. That seems nicer to me than each driver having to retain > (redundant) state. > > Regardless, this patch itself is fine.
Well, it's also largely incomplete as you point out, so I don't think we gain an awful lot from merging it as-is.
Will
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