From nobody Mon Feb 9 20:30:20 2026 Received: from mail-pj1-f74.google.com (mail-pj1-f74.google.com [209.85.216.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2AA4B2116E7 for ; Mon, 3 Feb 2025 22:39:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.74 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738622365; cv=none; b=XxBit54LKij9tghwd3WO90pbNj7a10p9iF9achAxB5Q0DrI5FgwCWzO65ru7PO5cs3NkysL2voDjHgrVQFftHH9+740lFaziyUenGv+W2JEe/H/6tkuuGy3krvDohaVdTbmdrYyAnA9j3O37MGrZCRWRqi/eW1dvPTZLHf1XU0I= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738622365; c=relaxed/simple; bh=yALvHvPZ06XHv8lSBAulVCm+vGbBL+K++sbCUEtN9RI=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=Jiy+4Sjcxkyp3ZLRq0cefHeffuZGJfbgqXzb3iXWC/+0t2utejaw8+gkqaPQPB+354+nnVTXM25IvpSk5cpSEKSaADl2EcO90HZUsbkDvDyuOC9dmVO4OwGpAeUBzKqoiSdhRjBm2ENb1tuO1k1Y2Mhfs6AiD03CtiZDPfdc+RE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--almasrymina.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=WfROW+VX; arc=none smtp.client-ip=209.85.216.74 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--almasrymina.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="WfROW+VX" Received: by mail-pj1-f74.google.com with SMTP id 98e67ed59e1d1-2ef9e4c5343so13795421a91.0 for ; Mon, 03 Feb 2025 14:39:23 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1738622362; x=1739227162; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=XpaVlDvetL7z/kA++uxshgtjRqWTMmKZzr7CrXSNsGU=; b=WfROW+VXY1yvFsA+uFmmfgXqll1DmLzDzrgpArestABSdItWp5ekZLfAAPSN4kPyhx AX/yhIo+T4V1ip8Mmb7sIZL0kHYEpwpkueAeSLEVoFjw7LDJzxirJ7cF1AivxjLUvrAK 9+TFBHMyCJg3i0RhEGJtVkBo5VUp5iwMnpUqIVIsn/n1IY1v278UqsLTfYEonBOWm3Tf BGo48DSJUzIKyk70cOIO3XoUiPiL40846UPA2a5o+KeZo8o8/uoki5JY84kHCB6DTuLw +BkBYL8qVCOUmt6AcU1W1egwQ9zlYpc5sOuz9WA0TUExOpH2mRd37LDGbjqaB8csbTVW iMmA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1738622362; x=1739227162; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=XpaVlDvetL7z/kA++uxshgtjRqWTMmKZzr7CrXSNsGU=; b=pvz3J0/0gLt+ARBQCHMFykgqn8A3cP3YHzcAJDTkdQSAywF7PPzX96/pKb83j4L/bg tsidLryTkh8uUfH5zfEOEwgl6wczsDw0yEPkrIceFsXqEAX4z6UNzyzfFQJWn9aHG88L SaQvoQFjZozCZmaaE6e7FDqjMOPjqMArU6z3VXkrnD+a25ddTMydsjLok5qSbQy3dcui QOr66NDh0eIfRPVoh7s9+CtGUOszcuaOyqVH/ROzqShMjSn1g/njBKvH1YhyT6t1YIOg mt3PB1UPd8nSvFV1+DBC43fq+LAcFObfWQCDar7HQ7CsG/o+r8Nrf4w521qdsVqFNsnU B06A== X-Forwarded-Encrypted: i=1; AJvYcCWk7o8syPVCrk02hce4xDC/OOaf2xlS5hqKEQaPw+POF71nZx1n6dr64g7laodBpLoGnvlAc2b78bf8RdA=@vger.kernel.org X-Gm-Message-State: AOJu0YyMA3jI4fHJDTQ2AN1taZ9eqPQSIBArnaCDhv/asWcUboDzu/uA bMhpybHSRiqvY2L5uFa5mv0OAmT355xhdJ82UsRJ5gZQinQEX0CFDr5ljqsCvSBab5BaQP2ul0n dDnd1mL+Bfru5aO1e+nN9Gw== X-Google-Smtp-Source: AGHT+IHFrrUGIUMZPQVWORflbnoiwG8EF+LwGiuHsHmsbKPYPdBL0OXUy8C/28kCzgcGFB8+h6vXLwmDicd/+JIqDg== X-Received: from pfbll11.prod.google.com ([2002:a05:6a00:728b:b0:728:b8e3:9934]) (user=almasrymina job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a21:b93:b0:1e1:bdae:e054 with SMTP id adf61e73a8af0-1ed7a643882mr39519231637.25.1738622362684; Mon, 03 Feb 2025 14:39:22 -0800 (PST) Date: Mon, 3 Feb 2025 22:39:13 +0000 In-Reply-To: <20250203223916.1064540-1-almasrymina@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250203223916.1064540-1-almasrymina@google.com> X-Mailer: git-send-email 2.48.1.362.g079036d154-goog Message-ID: <20250203223916.1064540-4-almasrymina@google.com> Subject: [PATCH net-next v3 3/6] net: add get_netmem/put_netmem support From: Mina Almasry To: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux.dev, linux-kselftest@vger.kernel.org Cc: Mina Almasry , Donald Hunter , Jakub Kicinski , "David S. Miller" , Eric Dumazet , Paolo Abeni , Simon Horman , Jonathan Corbet , Andrew Lunn , Neal Cardwell , David Ahern , "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , "=?UTF-8?q?Eugenio=20P=C3=A9rez?=" , Stefan Hajnoczi , Stefano Garzarella , Shuah Khan , sdf@fomichev.me, asml.silence@gmail.com, dw@davidwei.uk, Jamal Hadi Salim , Victor Nogueira , Pedro Tammela , Samiullah Khawaja Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Currently net_iovs support only pp ref counts, and do not support a page ref equivalent. This is fine for the RX path as net_iovs are used exclusively with the pp and only pp refcounting is needed there. The TX path however does not use pp ref counts, thus, support for get_page/put_page equivalent is needed for netmem. Support get_netmem/put_netmem. Check the type of the netmem before passing it to page or net_iov specific code to obtain a page ref equivalent. For dmabuf net_iovs, we obtain a ref on the underlying binding. This ensures the entire binding doesn't disappear until all the net_iovs have been put_netmem'ed. We do not need to track the refcount of individual dmabuf net_iovs as we don't allocate/free them from a pool similar to what the buddy allocator does for pages. This code is written to be extensible by other net_iov implementers. get_netmem/put_netmem will check the type of the netmem and route it to the correct helper: pages -> [get|put]_page() dmabuf net_iovs -> net_devmem_[get|put]_net_iov() new net_iovs -> new helpers Signed-off-by: Mina Almasry --- v2: - Add comment on top of refcount_t ref explaining the usage in the XT path. - Fix missing definition of net_devmem_dmabuf_binding_put in this patch. --- include/linux/skbuff_ref.h | 4 ++-- include/net/netmem.h | 3 +++ net/core/devmem.c | 10 ++++++++++ net/core/devmem.h | 20 ++++++++++++++++++++ net/core/skbuff.c | 30 ++++++++++++++++++++++++++++++ 5 files changed, 65 insertions(+), 2 deletions(-) diff --git a/include/linux/skbuff_ref.h b/include/linux/skbuff_ref.h index 0f3c58007488..9e49372ef1a0 100644 --- a/include/linux/skbuff_ref.h +++ b/include/linux/skbuff_ref.h @@ -17,7 +17,7 @@ */ static inline void __skb_frag_ref(skb_frag_t *frag) { - get_page(skb_frag_page(frag)); + get_netmem(skb_frag_netmem(frag)); } =20 /** @@ -40,7 +40,7 @@ static inline void skb_page_unref(netmem_ref netmem, bool= recycle) if (recycle && napi_pp_put_page(netmem)) return; #endif - put_page(netmem_to_page(netmem)); + put_netmem(netmem); } =20 /** diff --git a/include/net/netmem.h b/include/net/netmem.h index 1b58faa4f20f..d30f31878a09 100644 --- a/include/net/netmem.h +++ b/include/net/netmem.h @@ -245,4 +245,7 @@ static inline unsigned long netmem_get_dma_addr(netmem_= ref netmem) return __netmem_clear_lsb(netmem)->dma_addr; } =20 +void get_netmem(netmem_ref netmem); +void put_netmem(netmem_ref netmem); + #endif /* _NET_NETMEM_H */ diff --git a/net/core/devmem.c b/net/core/devmem.c index 3bba3f018df0..20985a570662 100644 --- a/net/core/devmem.c +++ b/net/core/devmem.c @@ -333,6 +333,16 @@ void dev_dmabuf_uninstall(struct net_device *dev) } } =20 +void net_devmem_get_net_iov(struct net_iov *niov) +{ + net_devmem_dmabuf_binding_get(niov->owner->binding); +} + +void net_devmem_put_net_iov(struct net_iov *niov) +{ + net_devmem_dmabuf_binding_put(niov->owner->binding); +} + /*** "Dmabuf devmem memory provider" ***/ =20 int mp_dmabuf_devmem_init(struct page_pool *pool) diff --git a/net/core/devmem.h b/net/core/devmem.h index 76099ef9c482..8b51caff5a0e 100644 --- a/net/core/devmem.h +++ b/net/core/devmem.h @@ -27,6 +27,10 @@ struct net_devmem_dmabuf_binding { * The binding undos itself and unmaps the underlying dmabuf once all * those refs are dropped and the binding is no longer desired or in * use. + * + * net_devmem_get_net_iov() on dmabuf net_iovs will increment this + * reference, making sure that the binding remains alive until all the + * net_iovs are no longer used. */ refcount_t ref; =20 @@ -119,6 +123,9 @@ net_devmem_dmabuf_binding_put(struct net_devmem_dmabuf_= binding *binding) __net_devmem_dmabuf_binding_free(binding); } =20 +void net_devmem_get_net_iov(struct net_iov *niov); +void net_devmem_put_net_iov(struct net_iov *niov); + struct net_iov * net_devmem_alloc_dmabuf(struct net_devmem_dmabuf_binding *binding); void net_devmem_free_dmabuf(struct net_iov *ppiov); @@ -126,6 +133,19 @@ void net_devmem_free_dmabuf(struct net_iov *ppiov); #else struct net_devmem_dmabuf_binding; =20 +static inline void +net_devmem_dmabuf_binding_put(struct net_devmem_dmabuf_binding *binding) +{ +} + +static inline void net_devmem_get_net_iov(struct net_iov *niov) +{ +} + +static inline void net_devmem_put_net_iov(struct net_iov *niov) +{ +} + static inline void __net_devmem_dmabuf_binding_free(struct net_devmem_dmabuf_binding *binding) { diff --git a/net/core/skbuff.c b/net/core/skbuff.c index a441613a1e6c..815245d5c36b 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -88,6 +88,7 @@ #include =20 #include "dev.h" +#include "devmem.h" #include "netmem_priv.h" #include "sock_destructor.h" =20 @@ -7290,3 +7291,32 @@ bool csum_and_copy_from_iter_full(void *addr, size_t= bytes, return false; } EXPORT_SYMBOL(csum_and_copy_from_iter_full); + +void get_netmem(netmem_ref netmem) +{ + if (netmem_is_net_iov(netmem)) { + /* Assume any net_iov is devmem and route it to + * net_devmem_get_net_iov. As new net_iov types are added they + * need to be checked here. + */ + net_devmem_get_net_iov(netmem_to_net_iov(netmem)); + return; + } + get_page(netmem_to_page(netmem)); +} +EXPORT_SYMBOL(get_netmem); + +void put_netmem(netmem_ref netmem) +{ + if (netmem_is_net_iov(netmem)) { + /* Assume any net_iov is devmem and route it to + * net_devmem_put_net_iov. As new net_iov types are added they + * need to be checked here. + */ + net_devmem_put_net_iov(netmem_to_net_iov(netmem)); + return; + } + + put_page(netmem_to_page(netmem)); +} +EXPORT_SYMBOL(put_netmem); --=20 2.48.1.362.g079036d154-goog