Re: [patch 32/32] genirq/msi: Convert storage to xarray

Greg Kroah-Hartman
2021-11-27T12:35:30Z

On Sat, Nov 27, 2021 at 02:23:17AM +0100, Thomas Gleixner wrote:
> The current linked list storage for MSI descriptors is suboptimal in
> several ways:
>
> 1) Looking up a MSI desciptor requires a O(n) list walk in the worst case
>
> 2) The upcoming support of runtime expansion of MSI-X vectors would need
> to do a full list walk to figure out whether a particular index is
> already associated.
>
> 3) Runtime expansion of sparse allocations is even more complex as the
> current implementation assumes an ordered list (increasing MSI index).
>
> Use an xarray which solves all of the above problems nicely.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
> include/linux/msi.h | 19 ++---
> kernel/irq/msi.c | 188 ++++++++++++++++++++++------------------------------
> 2 files changed, 90 insertions(+), 117 deletions(-)

Much simpler code too, nice!

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>