powerpc: MSI: Fix race condition in tearing down MSI interrupts

[Michael Ellerman]

On Thu, 2015-10-09 at 04:36:21 UTC, Paul Mackerras wrote:
> This fixes a race which can result in the same virtual IRQ number
> being assigned to two different MSI interrupts.  The most visible
> consequence of that is usually a warning and stack trace from the
> sysfs code about an attempt to create a duplicate entry in sysfs.

<snip>

> The pattern of calling msi_bitmap_free_hwirqs() before
> irq_dispose_mapping() appears in 5 places under arch/powerpc, and
> appears to have originated in commit 05af7bd2d75e ("[POWERPC] MPIC
> U3/U4 MSI backend") from 2007.
> 
> Reported-by: Alexey Kardashevskiy <aik at ozlabs.ru>
> Signed-off-by: Paul Mackerras <paulus at samba.org>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/e297c939b745e420ef0b9dc9

cheers