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[76.102.12.149]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-2ca78dfd323sm404829eec.1.2026.04.01.11.10.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 01 Apr 2026 11:10:23 -0700 (PDT) Date: Wed, 1 Apr 2026 11:10:22 -0700 From: Stanislav Fomichev To: Breno Leitao Cc: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Kuniyuki Iwashima , Willem de Bruijn , metze@samba.org, axboe@kernel.dk, Stanislav Fomichev , io-uring@vger.kernel.org, bpf@vger.kernel.org, netdev@vger.kernel.org, Linus Torvalds , linux-kernel@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH net-next v2 2/4] net: call getsockopt_iter if available Message-ID: References: <20260401-getsockopt-v2-0-611df6771aff@debian.org> <20260401-getsockopt-v2-2-611df6771aff@debian.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: On 04/01, Breno Leitao wrote: > On Wed, Apr 01, 2026 at 09:34:04AM -0700, Stanislav Fomichev wrote: > > > +static int do_sock_getsockopt_iter(struct socket *sock, > > > + const struct proto_ops *ops, int level, > > > + int optname, sockptr_t optval, > > > + sockptr_t optlen) > > > > If we want to eventually remove sockptr_t, why not make this new handler > > work with iov_iters from the beginning? The callers can have some new temporary > > sockptr_to_iter() or something? > > The goal is to eliminate __user memory from the callbacks entirely, which > would make sockptr_t unnecessary. This series removes the callbacks that > originally necessitated sockptr_t's existence. > > Therefore, working from the callbacks back to userspace seem to be a more > logical approach than replacing the middle layers of the implementation, > and then touching the callbacks. > > So, yes, the sockptr_t() is used here as temporary glue to be able to > get rid of the elephant in the room. So maybe something like this is better to communicate your long term intent? } else if (ops->getsockopt_iter) { optval = sockptr_to_iter(optval) optlen = sockptr_to_iter(optlen) do_sock_getsockopt_iter(...) /* does not know what sockpt_t is */ } ? Then your new do_sock_getsockopt_iter is sockptr-free from the beginning and at some point we'll just drop/move those sockptr_to_iter calls? > > > + /* iter is initialized as ITER_DEST. Callbacks that need to read > > > + * from optval (e.g. PACKET_HDRLEN) must flip data_source to > > > + * ITER_SOURCE, then restore ITER_DEST before writing back. > > > + */ > > > > Have you considered creating two iters? opt.iter_in and opt.iter_out. > > That way you don't have to flip the source back and forth in the > > handlers. > > That's a good suggestion I hadn't considered. My initial thought was to > create a helper like sockopt_read_val() to handle the flip-read-flip > dance. > > Would opt.iter_in and opt.iter_out be clearer than the helper approach? > > Thanks for the review, > --breno I hope this way it will be easier to review protocol handler changes. For example, looking at your AF_PACKET patch, you won't have to care about flipping the source and doing the revert. Most/all of the changes will be simple: - s/get_user(len, optlen)/len = opt->optlen/ - s/put_user(len, optlen)/opt->optlen = len/ - s/copy_from_user(xxx, optval, len)/copy_from_iter(xxx, len, &opt->iter_in)/ - s/copy_to_user(optval, xxx, len)/copy_to_iter(xxx, len, &opt->iter_out)/ Might be even possible to express these with coccinelle?