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

[Greg Kroah-Hartman]

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@xxxxxxxxxxxxx>
> ---
>  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@xxxxxxxxxxxxxxxxxxx>