Re: [PATCH net-next v11 2/6] tls: Re-present partially-consumed records in tls_sw_read_sock()

[Sabrina Dubroca <sd@queasysnail.net>]

2026-05-26, 10:21:32 -0400, Chuck Lever wrote:
> From: Chuck Lever <chuck.lever@oracle.com>
> 
> The tls_sw_read_sock() loop releases the current skb whether
> read_actor() consumed the full record or only a prefix. When
> the actor takes only part of the record and leaves desc->count
> non-zero, the remainder is lost: skb is neither requeued nor
> freed, and the next iteration overwrites it during dequeue or
> tls_rx_rec_wait().
> 
> No mainline consumer reaches this path today. The only
> in-tree TLS read_sock user is nvme/tcp, whose actor
> nvme_tcp_recv_skb() loops until the input length is exhausted
> and returns either the full length or a negative error.
> 
> The path becomes reachable with the upcoming NFSD svcsock
> receive built on read_sock_cmsg. Its data actor,
> svc_tcp_recv_actor(), parses an RPC fragment stream
> incrementally and returns at fragment boundaries. When a TLS
> record carries the tail of one RPC fragment plus the head of
> the next, the actor returns fewer bytes than offered while
> leaving desc->count non-zero, and without re-presentation the
> trailing fragment header vanishes.
> 
> __tcp_read_sock() handles the equivalent case for plain TCP
> by leaving the unread bytes available for the next iteration
> to re-present, via sequence-number re-lookup. Adopt the same
> loop-level behavior: when read_actor() consumes only part of
> the record, update rxm->offset and rxm->full_len and requeue
> the skb to the head of rx_list so the next iteration
> re-presents the unread bytes. Switch the open-ended for-loop
> to "while (desc->count)" so the partial- and full-consume
> arms share a single exit check and read_actor() is not
> re-invoked once desc->count is exhausted.
> 
> Cc: Sagi Grimberg <sagi@grimberg.me>
> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---
>  net/tls/tls_sw.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)

Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>

-- 
Sabrina