linux-kernel - Re: [PATCH v2] irq: generic-chip: provide irq_free_generic

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Date:   Thu, 9 Mar 2017 11:17:29 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Bartosz Golaszewski <bgolaszewski@...libre.com>
cc:     Marc Zyngier <marc.zyngier@....com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] irq: generic-chip: provide irq_free_generic_chip()

On Wed, 8 Mar 2017, Bartosz Golaszewski wrote:

> Some users of irq_alloc_generic_chip() are modules which can be
> removed (e.g. gpio-ml-ioh) but have no means of freeing the allocated
> generic chip. Provide a function for that.

They have means, i.e. kfree(gc). If you want a wrapper for that then please
make it a simple static inline w/o the bloat of an exported symbol.

But, what you really want is a proper counterpart to
irq_alloc_generic_chip() which undoes everything what
irq_alloc_generic_chip() does.

You have to call irq_remove_generic_chip() before calling kfree() or the
wrapper anyway. And looking at the 3 users of irq_remove_generic_chip():

Two of them (drivers/gpio/gpio-tb10x.c drivers/mfd/jz4740-adc.c) do

    irq_remove_generic_chip(gc)
    kfree(gc)

The third one (arch/arm/mach-omap2/prm_common.c) leaks the generic chip
memory....

So the proper solution is to rename irq_remove_generic_chip() to
irq_destroy_generic_chip() and do the kfree() at the end of that function.

Hmm?

	tglx