From 034dd340b08be1f2f0477ad16131d609f9dbd53c Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 30 Aug 2026 09:22:00 -0700 Subject: Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace Pull tracing fixes from Steven Rostedt: - Fix error output of boot instance creation failure Currently if a boot instance creation fails, instead of printing out the name of the instance that failed, it prints "(null)". That is because it prints "cur_str" that had already been processed by strsep(). Print the saved name instead. While at it, print the error code of the failure. - Fix use-after-free for same named historgrams Histograms can be named so that they can be used in multiple events. But if the named histogram has a variable attached, the second event that uses the named histogram which duplicates it and needs to free the original after duplication leaves the old variable in place and still visible. If another histogram uses than variable, it will use the stale one which will try to reference the freed duplicate histogram and crash the kernel. Free the duplicate variables along with the duplicated histogram data. - Check return value of kthread_run() in event self test The events self tests uses a kthread for testing but does not check if it succeeded in creating a kthread. If the kthread creation were to fail, the code will still try to call kthread_stop() on the error returned. - Fix race between reading trace_pipe and updating subbuffer size If a user is reading the trace_pipe file at the same time they update the ring buffer sub-buffer size, can cause the trace_pipe read to read stale data. Add trace_access_lock() around updating the ring buffer sub-buffer size. - Fix eventfs_inode on failure path in creation of the events directory In the creation of the "events" directory, if after allocating the eventfs_inode a failure is detected, it calls cleanup_ei() which calls free_ei(). The free_ei() will test if eventfs_inode being freed has no children. It is a bug if it does. But on the failure case of the creation of the "events" directory, the children lists have not yet been initialized and the free will trigger a warning because list_empty() on an uninitialized list returns false. Move the initialization into init_ei() where it makes more sense and makes sure that a created eventfs_inode has its lists initialized upon creation. - Check return value of kthread_run() in ftrace direct sample code The sample code that shows how to use the ftrace direct calls does not test the return of kthread_run() to see if it succeeds. Return a failure if the kthread_run() doesn't succeed. - Clear user events state on fork in case of alloc failure On fork, the child gets a pointer to the parent's user events state. It makes a copy of it then updates the child's pointer to it. But if the allocation fails, the duplication function leaves the child with a pointer to its parent's descriptor. When the child cleans up its data, it will free the parent's descriptor while the parent is still using it. In the duplication function, set the child's user_event_mm to NULL before testing if the allocation succeeded, and when it exits it will not free the parent's descriptor. - Fix retry exhaustion in simple ring buffer reader swap simple_ring_buffer_swap_reader_page() starts with retry set to 8 and post-decrements it only after a failed link replacement. On the final attempt, a successful replacement leaves retry at zero, while a failed replacement leaves it at -1. But the check for success expects the retry value to be non-zero and exits with an error on zero. This is the opposite result. Fix it. - Fail nicely when the remote swap_reader_page() returns an error Currently, if the swap_reader_page() of a remote buffer fails, it triggers a WARN_ON_ONCE() and continues normally. Instead, have it exit with an error and a pr_warn() print instead of a full WARNING. * tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: ring-buffer: Stop remote reader update when page swap fails tracing: Fix retry exhaustion in simple ring buffer reader swap tracing/user_events: Clear copied tracing state before fork duplication samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify eventfs: Initialize ei->children and ei->list in init_ei() tracing: Fix use-after-free in trace_pipe read on sub-buffer order change tracing: Fix crash passing ERR_PTR to kthread_stop() tracing: Fix use-after-free with same-name named triggers tracing: Fix logged instance name on creation failure --- Documentation/networking/mptcp-sysctl.rst | 166 ++++++++++++++++++++++++++++++ 1 file changed, 166 insertions(+) create mode 100644 Documentation/networking/mptcp-sysctl.rst (limited to 'Documentation/networking/mptcp-sysctl.rst') diff --git a/Documentation/networking/mptcp-sysctl.rst b/Documentation/networking/mptcp-sysctl.rst new file mode 100644 index 000000000..b9b5f58e0 --- /dev/null +++ b/Documentation/networking/mptcp-sysctl.rst @@ -0,0 +1,166 @@ +.. SPDX-License-Identifier: GPL-2.0 + +===================== +MPTCP Sysfs variables +===================== + +/proc/sys/net/mptcp/* Variables +=============================== + +add_addr_timeout - INTEGER (seconds) + Set the maximum value of timeout after which an ADD_ADDR control message + will be resent to an MPTCP peer that has not acknowledged a previous + ADD_ADDR message. A dynamically estimated retransmission timeout based + on the estimated connection round-trip-time is used if this value is + lower than the maximum one. + + Do not retransmit if set to 0. + + The default value matches TCP_RTO_MAX. This is a per-namespace + sysctl. + + Default: 120 + +add_addr_v6_port_drop_ts - BOOLEAN + Control whether preparing an ADD_ADDR with an IPv6 address and a port + should drop the TCP timestamps option to have enough option space to + send the signal. + + If there is not enough option space, and the TCP timestamps option + cannot be dropped, the signal cannot be sent. Note that dropping the TCP + timestamps option for one packet of the connection could disrupt some + middleboxes: even if it should be unlikely, they could drop the packet + or block the connection. This is a per-namespace sysctl. + + Default: 1 (enabled) + +allow_join_initial_addr_port - BOOLEAN + Allow peers to send join requests to the IP address and port number used + by the initial subflow if the value is 1. This controls a flag that is + sent to the peer at connection time, and whether such join requests are + accepted or denied. + + Joins to addresses advertised with ADD_ADDR are not affected by this + value. + + This is a per-namespace sysctl. + + Default: 1 + +available_path_managers - STRING + Shows the available path managers choices that are registered. More + path managers may be available, but not loaded. + +available_schedulers - STRING + Shows the available schedulers choices that are registered. More packet + schedulers may be available, but not loaded. + +blackhole_timeout - INTEGER (seconds) + Initial time period in second to disable MPTCP on active MPTCP sockets + when a MPTCP firewall blackhole issue happens. This time period will + grow exponentially when more blackhole issues get detected right after + MPTCP is re-enabled and will reset to the initial value when the + blackhole issue goes away. + + 0 to disable the blackhole detection. This is a per-namespace sysctl. + + Default: 3600 + +checksum_enabled - BOOLEAN + Control whether DSS checksum can be enabled. + + DSS checksum can be enabled if the value is nonzero. This is a + per-namespace sysctl. + + Default: 0 + +close_timeout - INTEGER (seconds) + Set the make-after-break timeout: in absence of any close or + shutdown syscall, MPTCP sockets will maintain the status + unchanged for such time, after the last subflow removal, before + moving to TCP_CLOSE. + + The default value matches TCP_TIMEWAIT_LEN. This is a per-namespace + sysctl. + + Default: 60 + +enabled - BOOLEAN + Control whether MPTCP sockets can be created. + + MPTCP sockets can be created if the value is 1. This is a + per-namespace sysctl. + + Default: 1 (enabled) + +path_manager - STRING + Set the default path manager name to use for each new MPTCP + socket. In-kernel path management will control subflow + connections and address advertisements according to + per-namespace values configured over the MPTCP netlink + API. Userspace path management puts per-MPTCP-connection subflow + connection decisions and address advertisements under control of + a privileged userspace program, at the cost of more netlink + traffic to propagate all of the related events and commands. + + This is a per-namespace sysctl. + + * "kernel" - In-kernel path manager + * "userspace" - Userspace path manager + + Default: "kernel" + +pm_type - INTEGER + Set the default path manager type to use for each new MPTCP + socket. In-kernel path management will control subflow + connections and address advertisements according to + per-namespace values configured over the MPTCP netlink + API. Userspace path management puts per-MPTCP-connection subflow + connection decisions and address advertisements under control of + a privileged userspace program, at the cost of more netlink + traffic to propagate all of the related events and commands. + + This is a per-namespace sysctl. + + Deprecated since v6.15, use path_manager instead. + + * 0 - In-kernel path manager + * 1 - Userspace path manager + + Default: 0 + +scheduler - STRING + Select the scheduler of your choice. + + Support for selection of different schedulers. This is a per-namespace + sysctl. + + Default: "default" + +stale_loss_cnt - INTEGER + The number of MPTCP-level retransmission intervals with no traffic and + pending outstanding data on a given subflow required to declare it stale. + The packet scheduler ignores stale subflows. + A low stale_loss_cnt value allows for fast active-backup switch-over, + an high value maximize links utilization on edge scenarios e.g. lossy + link with high BER or peer pausing the data processing. + + This is a per-namespace sysctl. + + Default: 4 + +syn_retrans_before_tcp_fallback - INTEGER + The number of SYN + MP_CAPABLE retransmissions before falling back to + TCP, i.e. dropping the MPTCP options. In other words, if all the packets + are dropped on the way, there will be: + + * The initial SYN with MPTCP support + * This number of SYN retransmitted with MPTCP support + * The next SYN retransmissions will be without MPTCP support + + 0 means the first retransmission will be done without MPTCP options. + >= 128 means that all SYN retransmissions will keep the MPTCP options. A + lower number might increase false-positive MPTCP blackholes detections. + This is a per-namespace sysctl. + + Default: 2 -- cgit v1.3.1