netdev - Re: [PATCH net-next v10 08/16] tls: Inline do_tcp

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Message-ID: <2267272.1686150217@warthog.procyon.org.uk>
Date: Wed, 07 Jun 2023 16:03:37 +0100
From: David Howells <dhowells@...hat.com>
To: Tariq Toukan <ttoukan.linux@...il.com>
Cc: dhowells@...hat.com, netdev@...r.kernel.org,
    "David S. Miller" <davem@...emloft.net>,
    Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
    Paolo Abeni <pabeni@...hat.com>,
    Willem de Bruijn <willemdebruijn.kernel@...il.com>,
    David Ahern <dsahern@...nel.org>,
    Matthew Wilcox <willy@...radead.org>,
    Al Viro <viro@...iv.linux.org.uk>,
    Christoph Hellwig <hch@...radead.org>, Jens Axboe <axboe@...nel.dk>,
    Jeff Layton <jlayton@...nel.org>,
    Christian Brauner <brauner@...nel.org>,
    Chuck Lever III <chuck.lever@...cle.com>,
    Linus Torvalds <torvalds@...ux-foundation.org>,
    linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
    linux-mm@...ck.org, Boris Pismenny <borisp@...dia.com>,
    John Fastabend <john.fastabend@...il.com>,
    Gal Pressman <gal@...dia.com>, ranro@...dia.com, samiram@...dia.com,
    drort@...dia.com, Tariq Toukan <tariqt@...dia.com>
Subject: Re: [PATCH net-next v10 08/16] tls: Inline do_tcp_sendpages()

Tariq Toukan <ttoukan.linux@...il.com> wrote:

> My team spotted a new degradation in TLS TX device offload, bisected to this
> patch.

I presume you're using some hardware (I'm guessing Mellanox?) that can
actually do TLS offload?  Unfortunately, I don't have any hardware that can do
this, so I can't test the tls_device stuff.

> From a quick look at the patch, it's not clear to me what's going wrong.
> Please let us know of any helpful information that we can provide to help in
> the debug.

Can you find out what source line this corresponds to?

	RIP: 0010:skb_splice_from_iter+0x102/0x300

Assuming you're building your own kernel, something like the following might
do the trick:

	echo "RIP: 0010:skb_splice_from_iter+0x102/0x300" |
	./scripts/decode_stacktrace.sh /my/built/vmlinux /my/build/tree

if you run it in the kernel source tree you're using and substitute the
paths to vmlinux and the build tree for modules.

David