linux-kernel - Re: [PATCH v2 1/2] xen/xenbus: avoid large structs and arrays on the stack

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Message-ID: <80b8927f-d654-44f3-a860-fb3e395652d6@oracle.com>
Date:   Thu, 2 Jul 2020 17:02:37 -0400
From:   Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:     Juergen Gross <jgross@...e.com>, xen-devel@...ts.xenproject.org,
        linux-kernel@...r.kernel.org, clang-built-linux@...glegroups.com
Cc:     Stefano Stabellini <sstabellini@...nel.org>,
        Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH v2 1/2] xen/xenbus: avoid large structs and arrays on the
 stack

On 7/1/20 8:16 AM, Juergen Gross wrote:
> xenbus_map_ring_valloc() and its sub-functions are putting quite large
> structs and arrays on the stack. This is problematic at runtime, but
> might also result in build failures (e.g. with clang due to the option
> -Werror,-Wframe-larger-than=... used).
>
> Fix that by moving most of the data from the stack into a dynamically
> allocated struct. Performance is no issue here, as
> xenbus_map_ring_valloc() is used only when adding a new PV device to
> a backend driver.
>
> While at it move some duplicated code from pv/hvm specific mapping
> functions to the single caller.
>
> Reported-by: Arnd Bergmann <arnd@...db.de>
> Signed-off-by: Juergen Gross <jgross@...e.com>


Reviewed-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>