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[188.28.126.24]) by smtp.gmail.com with ESMTPSA id ay1-20020a05600c1e0100b003a342933727sm3004519wmb.3.2022.08.10.08.51.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 Aug 2022 08:51:47 -0700 (PDT) From: Pavel Begunkov To: io-uring@vger.kernel.org, netdev@vger.kernel.org Cc: Jens Axboe , "David S . Miller" , Jakub Kicinski , kernel-team@fb.com, linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, Wei Liu , Paul Durrant , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, "Michael S . Tsirkin" , Jason Wang , Pavel Begunkov Subject: [RFC net-next io_uring 08/11] net: let callers provide ->msg_ubuf refs Date: Wed, 10 Aug 2022 16:49:16 +0100 Message-Id: <526fe4cb9cda287bedfc92b3888b48a4f3b0250b.1660124059.git.asml.silence@gmail.com> X-Mailer: git-send-email 2.37.0 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Some msg_ubuf providers like io_uring can keep elaborated ubuf_info reference batching and caching, so it will be of benefit to let the network layer to optionally steal some of the cached refs. Add UARGFL_GIFT_REF, if set the caller has at least one extra reference that it can gift away. If the network decides to take the ref it should clear the flag. Signed-off-by: Pavel Begunkov --- include/linux/skbuff.h | 14 ++++++++++++++ net/ipv4/ip_output.c | 1 + net/ipv6/ip6_output.c | 1 + 3 files changed, 16 insertions(+) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 45fe7f0648d0..972ec676e222 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -527,6 +527,11 @@ enum { * be freed until we return. */ UARGFL_CALLER_PINNED = BIT(0), + + /* The caller can gift one ubuf reference. The flag should be cleared + * when the reference is taken. + */ + UARGFL_GIFT_REF = BIT(1), }; /* @@ -1709,6 +1714,15 @@ static inline void net_zcopy_put(struct ubuf_info *uarg) uarg->callback(NULL, uarg, true); } +static inline bool net_zcopy_get_gift_ref(struct ubuf_info *uarg) +{ + bool has_ref; + + has_ref = uarg->flags & UARGFL_GIFT_REF; + uarg->flags &= ~UARGFL_GIFT_REF; + return has_ref; +} + static inline void net_zcopy_put_abort(struct ubuf_info *uarg, bool have_uref) { if (uarg) { diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index 546897a4b4fa..9d42b6dd6b78 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -1032,6 +1032,7 @@ static int __ip_append_data(struct sock *sk, paged = true; zc = true; uarg = msg->msg_ubuf; + extra_uref = net_zcopy_get_gift_ref(uarg); } } else if (sock_flag(sk, SOCK_ZEROCOPY)) { uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb)); diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 6d4f01a0cf6e..8d8a8bbdb8df 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -1557,6 +1557,7 @@ static int __ip6_append_data(struct sock *sk, paged = true; zc = true; uarg = msg->msg_ubuf; + extra_uref = net_zcopy_get_gift_ref(uarg); } } else if (sock_flag(sk, SOCK_ZEROCOPY)) { uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb));