Re: [PATCH RFC 1/5] net: Add distinct sk_psock field

Hannes Reinecke
2022-04-21T07:35:20Z

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
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