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Date:   Thu, 21 Apr 2022 09:35:05 +0200
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Subject: Re: [PATCH RFC 1/5] net: Add distinct sk_psock field
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To:     Chuck Lever <chuck.lever@oracle.com>, netdev@vger.kernel.org,
        linux-nfs@vger.kernel.org, linux-nvme@lists.infradead.org,
        linux-cifs@vger.kernel.org, linux-fsdevel@vger.kernel.org
Cc:     ak@tempesta-tech.com, borisp@nvidia.com, simo@redhat.com
References: <165030051838.5073.8699008789153780301.stgit@oracle-102.nfsv4.dev>
 <165030056960.5073.6664402939918720250.stgit@oracle-102.nfsv4.dev>
From:   Hannes Reinecke <hare@suse.de>
In-Reply-To: <165030056960.5073.6664402939918720250.stgit@oracle-102.nfsv4.dev>
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On 4/18/22 18:49, Chuck Lever wrote:
> The sk_psock facility populates the sk_user_data field with the
> address of an extra bit of metadata. User space sockets never
> populate the sk_user_data field, so this has worked out fine.
> 
> However, kernel consumers such as the RPC client and server do
> populate the sk_user_data field. The sk_psock() function cannot tell
> that the content of sk_user_data does not point to psock metadata,
> so it will happily return a pointer to something else, cast to a
> struct sk_psock.
> 
> Thus kernel consumers and psock currently cannot co-exist.
> 
> We could educate sk_psock() to return NULL if sk_user_data does
> not point to a struct sk_psock. However, a more general solution
> that enables full co-existence psock and other uses of sk_user_data
> might be more interesting.
> 
> Move the struct sk_psock address to its own pointer field so that
> the contents of the sk_user_data field is preserved.
> 
> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---
>   include/linux/skmsg.h |    2 +-
>   include/net/sock.h    |    4 +++-
>   net/core/skmsg.c      |    6 +++---
>   3 files changed, 7 insertions(+), 5 deletions(-)
> 
Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		           Kernel Storage Architect
hare@suse.de			                  +49 911 74053 688
SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg
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