kernel/Documentation/networking, branch linux-6.1.y

doc: fix seg6_flowlabel path

2025-10-29T13:04:33Z

[ Upstream commit 0b4b77eff5f8cd9be062783a1c1e198d46d0a753 ] This sysctl is not per interface; it's global per netns. Fixes: 292ecd9f5a94 ("doc: move seg6_flowlabel to seg6-sysctl.rst") Reported-by: Philippe Guibert Signed-off-by: Nicolas Dichtel Reviewed-by: Simon Horman Signed-off-by: David S. Miller Signed-off-by: Sasha Levin

docs: networking: can: change bcm_msg_head frames member to support flexible array

2025-09-19T14:29:58Z

[ Upstream commit 641427d5bf90af0625081bf27555418b101274cd ] The documentation of the 'bcm_msg_head' struct does not match how it is defined in 'bcm.h'. Changed the frames member to a flexible array, matching the definition in the header file. See commit 94dfc73e7cf4 ("treewide: uapi: Replace zero-length arrays with flexible-array members") Signed-off-by: Alex Tran Acked-by: Oliver Hartkopp Link: https://patch.msgid.link/20250904031709.1426895-1-alex.t.tran@gmail.com Fixes: 94dfc73e7cf4 ("treewide: uapi: Replace zero-length arrays with flexible-array members") Link: https://bugzilla.kernel.org/show_bug.cgi?id=217783 Signed-off-by: Marc Kleine-Budde Signed-off-by: Sasha Levin

bonding: Add independent control state machine

2025-08-28T14:26:18Z

[ Upstream commit 240fd405528bbf7fafa0559202ca7aa524c9cd96 ] Add support for the independent control state machine per IEEE 802.1AX-2008 5.4.15 in addition to the existing implementation of the coupled control state machine. Introduces two new states, AD_MUX_COLLECTING and AD_MUX_DISTRIBUTING in the LACP MUX state machine for separated handling of an initial Collecting state before the Collecting and Distributing state. This enables a port to be in a state where it can receive incoming packets while not still distributing. This is useful for reducing packet loss when a port begins distributing before its partner is able to collect. Added new functions such as bond_set_slave_tx_disabled_flags and bond_set_slave_rx_enabled_flags to precisely manage the port's collecting and distributing states. Previously, there was no dedicated method to disable TX while keeping RX enabled, which this patch addresses. Note that the regular flow process in the kernel's bonding driver remains unaffected by this patch. The extension requires explicit opt-in by the user (in order to ensure no disruptions for existing setups) via netlink support using the new bonding parameter coupled_control. The default value for coupled_control is set to 1 so as to preserve existing behaviour. Signed-off-by: Aahil Awatramani Reviewed-by: Hangbin Liu Link: https://lore.kernel.org/r/20240202175858.1573852-1-aahila@google.com Signed-off-by: Paolo Abeni Stable-dep-of: 0599640a21e9 ("bonding: send LACPDUs periodically in passive mode after receiving partner's LACPDU") Signed-off-by: Sasha Levin

mptcp: disable add_addr retransmission when timeout is 0

2025-08-28T14:26:16Z

[ Upstream commit f5ce0714623cffd00bf2a83e890d09c609b7f50a ] When add_addr_timeout was set to 0, this caused the ADD_ADDR to be retransmitted immediately, which looks like a buggy behaviour. Instead, interpret 0 as "no retransmissions needed". The documentation is updated to explicitly state that setting the timeout to 0 disables retransmission. Fixes: 93f323b9cccc ("mptcp: add a new sysctl add_addr_timeout") Cc: stable@vger.kernel.org Suggested-by: Matthieu Baerts Signed-off-by: Geliang Tang Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20250815-net-mptcp-misc-fixes-6-17-rc2-v1-5-521fe9957892@kernel.org Signed-off-by: Jakub Kicinski [ Apply to net/mptcp/pm_netlink.c , structural changes in mptcp_pm_alloc_anno_list ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

strparser: Add read_sock callback

2025-03-07T15:56:37Z

[ Upstream commit 0532a79efd68a4d9686b0385e4993af4b130ff82 ] Added a new read_sock handler, allowing users to customize read operations instead of relying on the native socket's read_sock. Signed-off-by: Jiayuan Chen Signed-off-by: Martin KaFai Lau Reviewed-by: Jakub Sitnicki Acked-by: John Fastabend Link: https://patch.msgid.link/20250122100917.49845-2-mrpre@163.com Stable-dep-of: 36b62df5683c ("bpf: Fix wrong copied_seq calculation") Signed-off-by: Sasha Levin

can: j1939: fix error in J1939 documentation.

2024-12-14T18:53:10Z

[ Upstream commit b6ec62e01aa4229bc9d3861d1073806767ea7838 ] The description of PDU1 format usage mistakenly referred to PDU2 format. Signed-off-by: Alexander Hölzl Acked-by: Oleksij Rempel Acked-by: Vincent Mailhol Link: https://patch.msgid.link/20241023145257.82709-1-alexander.hoelzl@gmx.net Signed-off-by: Marc Kleine-Budde Signed-off-by: Sasha Levin

net: provide macros for commonly copied lockless queue stop/wake code

2024-11-01T00:56:04Z

[ Upstream commit c91c46de6bbc1147ae5dfe046b87f5f3d6593215 ] A lot of drivers follow the same scheme to stop / start queues without introducing locks between xmit and NAPI tx completions. I'm guessing they all copy'n'paste each other's code. The original code dates back all the way to e1000 and Linux 2.6.19. Smaller drivers shy away from the scheme and introduce a lock which may cause deadlocks in netpoll. Provide macros which encapsulate the necessary logic. The macros do not prevent false wake ups, the extra barrier required to close that race is not worth it. See discussion in: https://lore.kernel.org/all/c39312a2-4537-14b4-270c-9fe1fbb91e89@gmail.com/ Acked-by: Herbert Xu Signed-off-by: Jakub Kicinski Stable-dep-of: 95ecba62e2fd ("net: fix races in netdev_tx_sent_queue()/dev_watchdog()") Signed-off-by: Sasha Levin

docs: net: reformat driver.rst from a list to sections

2024-11-01T00:56:04Z

[ Upstream commit d2f5c68e3f7157e874a759e382a5eaffa775b869 ] driver.rst had a historical form of list of common problems. In the age os Sphinx and rendered documentation it's better to use the more usual title + text format. This will allow us to render kdoc into the output more naturally. No changes to the actual text. Signed-off-by: Jakub Kicinski Stable-dep-of: 95ecba62e2fd ("net: fix races in netdev_tx_sent_queue()/dev_watchdog()") Signed-off-by: Sasha Levin

net: ena: Add dynamic recycling mechanism for rx buffers

2024-06-12T09:03:58Z

[ Upstream commit f7d625adeb7bc6a9ec83d32d9615889969d64484 ] The current implementation allocates page-sized rx buffers. As traffic may consist of different types and sizes of packets, in various cases, buffers are not fully used. This change (Dynamic RX Buffers - DRB) uses part of the allocated rx page needed for the incoming packet, and returns the rest of the unused page to be used again as an rx buffer for future packets. A threshold of 2K for unused space has been set in order to declare whether the remainder of the page can be reused again as an rx buffer. As a page may be reused, dma_sync_single_for_cpu() is added in order to sync the memory to the CPU side after it was owned by the HW. In addition, when the rx page can no longer be reused, it is being unmapped using dma_page_unmap(), which implicitly syncs and then unmaps the entire page. In case the kernel still handles the skbs pointing to the previous buffers from that rx page, it may access garbage pointers, caused by the implicit sync overwriting them. The implicit dma sync is removed by replacing dma_page_unmap() with dma_unmap_page_attrs() with DMA_ATTR_SKIP_CPU_SYNC flag. The functionality is disabled for XDP traffic to avoid handling several descriptors per packet. Signed-off-by: Arthur Kiyanovski Signed-off-by: Shay Agroskin Signed-off-by: David Arinzon Link: https://lore.kernel.org/r/20230612121448.28829-1-darinzon@amazon.com Signed-off-by: Jakub Kicinski Stable-dep-of: 2dc8b1e7177d ("net: ena: Fix redundant device NUMA node override") Signed-off-by: Sasha Levin

tcp: enforce receive buffer memory limits by allowing the tcp window to shrink

2023-10-19T21:08:54Z

[ Upstream commit b650d953cd391595e536153ce30b4aab385643ac ] Under certain circumstances, the tcp receive buffer memory limit set by autotuning (sk_rcvbuf) is increased due to incoming data packets as a result of the window not closing when it should be. This can result in the receive buffer growing all the way up to tcp_rmem[2], even for tcp sessions with a low BDP. To reproduce: Connect a TCP session with the receiver doing nothing and the sender sending small packets (an infinite loop of socket send() with 4 bytes of payload with a sleep of 1 ms in between each send()). This will cause the tcp receive buffer to grow all the way up to tcp_rmem[2]. As a result, a host can have individual tcp sessions with receive buffers of size tcp_rmem[2], and the host itself can reach tcp_mem limits, causing the host to go into tcp memory pressure mode. The fundamental issue is the relationship between the granularity of the window scaling factor and the number of byte ACKed back to the sender. This problem has previously been identified in RFC 7323, appendix F [1]. The Linux kernel currently adheres to never shrinking the window. In addition to the overallocation of memory mentioned above, the current behavior is functionally incorrect, because once tcp_rmem[2] is reached when no remediations remain (i.e. tcp collapse fails to free up any more memory and there are no packets to prune from the out-of-order queue), the receiver will drop in-window packets resulting in retransmissions and an eventual timeout of the tcp session. A receive buffer full condition should instead result in a zero window and an indefinite wait. In practice, this problem is largely hidden for most flows. It is not applicable to mice flows. Elephant flows can send data fast enough to "overrun" the sk_rcvbuf limit (in a single ACK), triggering a zero window. But this problem does show up for other types of flows. Examples are websockets and other type of flows that send small amounts of data spaced apart slightly in time. In these cases, we directly encounter the problem described in [1]. RFC 7323, section 2.4 [2], says there are instances when a retracted window can be offered, and that TCP implementations MUST ensure that they handle a shrinking window, as specified in RFC 1122, section 4.2.2.16 [3]. All prior RFCs on the topic of tcp window management have made clear that sender must accept a shrunk window from the receiver, including RFC 793 [4] and RFC 1323 [5]. This patch implements the functionality to shrink the tcp window when necessary to keep the right edge within the memory limit by autotuning (sk_rcvbuf). This new functionality is enabled with the new sysctl: net.ipv4.tcp_shrink_window Additional information can be found at: https://blog.cloudflare.com/unbounded-memory-usage-by-tcp-for-receive-buffers-and-how-we-fixed-it/ [1] https://www.rfc-editor.org/rfc/rfc7323#appendix-F [2] https://www.rfc-editor.org/rfc/rfc7323#section-2.4 [3] https://www.rfc-editor.org/rfc/rfc1122#page-91 [4] https://www.rfc-editor.org/rfc/rfc793 [5] https://www.rfc-editor.org/rfc/rfc1323 Signed-off-by: Mike Freemon Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Sasha Levin