sk_ll_usec is read locklessly from sk_can_busy_loop()
while another thread can change its value in sock_setsockopt()
This is correct but needs annotations.
BUG: KCSAN: data-race in __skb_try_recv_datagram / sock_setsockopt
write to 0xffff88814eb5f904 of 4 bytes by task 14011 on cpu 0:
sock_setsockopt+0x1287/0x2090 net/core/sock.c:1175
__sys_setsockopt+0x14f/0x200 net/socket.c:2100
__do_sys_setsockopt net/socket.c:2115 [inline]
__se_sys_setsockopt net/socket.c:2112 [inline]
__x64_sys_setsockopt+0x62/0x70 net/socket.c:2112
do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
entry_SYSCALL_64_after_hwframe+0x44/0xae
read to 0xffff88814eb5f904 of 4 bytes by task 14001 on cpu 1:
sk_can_busy_loop include/net/busy_poll.h:41 [inline]
__skb_try_recv_datagram+0x14f/0x320 net/core/datagram.c:273
unix_dgram_recvmsg+0x14c/0x870 net/unix/af_unix.c:2101
unix_seqpacket_recvmsg+0x5a/0x70 net/unix/af_unix.c:2067
____sys_recvmsg+0x15d/0x310 include/linux/uio.h:244
___sys_recvmsg net/socket.c:2598 [inline]
do_recvmmsg+0x35c/0x9f0 net/socket.c:2692
__sys_recvmmsg net/socket.c:2771 [inline]
__do_sys_recvmmsg net/socket.c:2794 [inline]
__se_sys_recvmmsg net/socket.c:2787 [inline]
__x64_sys_recvmmsg+0xcf/0x150 net/socket.c:2787
do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
entry_SYSCALL_64_after_hwframe+0x44/0xae
value changed: 0x00000000 -> 0x00000101
Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 14001 Comm: syz-executor.3 Not tainted 5.13.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stephen reported the following build error for !CONFIG_NET_RX_BUSY_POLL
built kernels:
In file included from fs/select.c:32:
include/net/busy_poll.h: In function 'sk_mark_napi_id_once':
include/net/busy_poll.h:150:36: error: 'const struct sk_buff' has no member named 'napi_id'
150 | __sk_mark_napi_id_once_xdp(sk, skb->napi_id);
| ^~
Fix it by wrapping a CONFIG_NET_RX_BUSY_POLL around the helpers.
Fixes: b02e5a0ebb ("xsk: Propagate napi_id to XDP socket Rx path")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Björn Töpel <bjorn.topel@intel.com>
Link: https://lore.kernel.org/linux-next/20201201190746.7d3357fb@canb.auug.org.au
Add napi_id to the xdp_rxq_info structure, and make sure the XDP
socket pick up the napi_id in the Rx path. The napi_id is used to find
the corresponding NAPI structure for socket busy polling.
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://lore.kernel.org/bpf/20201130185205.196029-7-bjorn.topel@gmail.com
This option lets a user set a per socket NAPI budget for
busy-polling. If the options is not set, it will use the default of 8.
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/bpf/20201130185205.196029-3-bjorn.topel@gmail.com
The existing busy-polling mode, enabled by the SO_BUSY_POLL socket
option or system-wide using the /proc/sys/net/core/busy_read knob, is
an opportunistic. That means that if the NAPI context is not
scheduled, it will poll it. If, after busy-polling, the budget is
exceeded the busy-polling logic will schedule the NAPI onto the
regular softirq handling.
One implication of the behavior above is that a busy/heavy loaded NAPI
context will never enter/allow for busy-polling. Some applications
prefer that most NAPI processing would be done by busy-polling.
This series adds a new socket option, SO_PREFER_BUSY_POLL, that works
in concert with the napi_defer_hard_irqs and gro_flush_timeout
knobs. The napi_defer_hard_irqs and gro_flush_timeout knobs were
introduced in commit 6f8b12d661 ("net: napi: add hard irqs deferral
feature"), and allows for a user to defer interrupts to be enabled and
instead schedule the NAPI context from a watchdog timer. When a user
enables the SO_PREFER_BUSY_POLL, again with the other knobs enabled,
and the NAPI context is being processed by a softirq, the softirq NAPI
processing will exit early to allow the busy-polling to be performed.
If the application stops performing busy-polling via a system call,
the watchdog timer defined by gro_flush_timeout will timeout, and
regular softirq handling will resume.
In summary; Heavy traffic applications that prefer busy-polling over
softirq processing should use this option.
Example usage:
$ echo 2 | sudo tee /sys/class/net/ens785f1/napi_defer_hard_irqs
$ echo 200000 | sudo tee /sys/class/net/ens785f1/gro_flush_timeout
Note that the timeout should be larger than the userspace processing
window, otherwise the watchdog will timeout and fall back to regular
softirq processing.
Enable the SO_BUSY_POLL/SO_PREFER_BUSY_POLL options on your socket.
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/bpf/20201130185205.196029-2-bjorn.topel@gmail.com
This will be useful to allow busy poll for tunneled traffic. In case of
busy poll for sessions over tunnels, the underlying physical device's
queues need to be polled.
Tunnels schedule NAPI either via netif_rx() for backlog queue or
schedule the gro_cell_poll(). netif_rx() propagates the valid skb->napi_id
to the socket. OTOH, gro_cell_poll() stamps the skb->napi_id again by
calling skb_mark_napi_id() with the tunnel NAPI which is not a busy poll
candidate. This was preventing tunneled traffic to use busy poll. A valid
NAPI ID in the skb indicates it was already marked for busy poll by a
NAPI driver and hence needs to be copied into the socket.
Signed-off-by: Amritha Nambiar <amritha.nambiar@intel.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms and conditions of the gnu general public license
version 2 as published by the free software foundation this program
is distributed in the hope it will be useful but without any
warranty without even the implied warranty of merchantability or
fitness for a particular purpose see the gnu general public license
for more details you should have received a copy of the gnu general
public license along with this program if not write to the free
software foundation inc 51 franklin st fifth floor boston ma 02110
1301 usa
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 111 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190530000436.567572064@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Fold it into the only caller to make the code simpler and easier to read.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
There is no point in hiding this logic in a helper. Also remove the
useless events != 0 check and only busy loop once we know we actually
have a poll method.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds a new field to sock_common 'skc_rx_queue_mapping'
which holds the receive queue number for the connection. The Rx queue
is marked in tcp_finish_connect() to allow a client app to do
SO_INCOMING_NAPI_ID after a connect() call to get the right queue
association for a socket. Rx queue is also marked in tcp_conn_request()
to allow syn-ack to go on the right tx-queue associated with
the queue on which syn is received.
Signed-off-by: Amritha Nambiar <amritha.nambiar@intel.com>
Signed-off-by: Sridhar Samudrala <sridhar.samudrala@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Factor out two busy poll related helpers for late reuse, and remove
a command that isn't very helpful, especially with the __poll_t
annotations in place.
Signed-off-by: Christoph Hellwig <hch@lst.de>
MIN_NAPI_ID is used in various places outside of
CONFIG_NET_RX_BUSY_POLL wrapping, so when it's not set
we run into build errors such as:
net/core/dev.c: In function 'dev_get_by_napi_id':
net/core/dev.c:886:16: error: ‘MIN_NAPI_ID’ undeclared (first use in this function)
if (napi_id < MIN_NAPI_ID)
^~~~~~~~~~~
Thus, have MIN_NAPI_ID always defined to fix these errors.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Move the core functionality in sk_busy_loop() to napi_busy_loop() and
make it independent of sk.
This enables re-using this function in epoll busy loop implementation.
Signed-off-by: Sridhar Samudrala <sridhar.samudrala@intel.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch flips the logic we were using to determine if the busy polling
has timed out. The main motivation for this is that we will need to
support two different possible timeout values in the future and by
recording the start time rather than when we would want to end we can focus
on making the end_time specific to the task be it epoll or socket based
polling.
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
checking the return value of sk_busy_loop. As there are only a few
consumers of that data, and the data being checked for can be replaced
with a check for !skb_queue_empty() we might as well just pull the code
out of sk_busy_loop and place it in the spots that actually need it.
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Instead of defining two versions of skb_mark_napi_id I think it is more
readable to just match the format of the sk_mark_napi_id functions and just
wrap the contents of the function instead of defining two versions of the
function. This way we can save a few lines of code since we only need 2 of
the ifdef/endif but needed 5 for the extra function declaration.
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch is a cleanup/fix for NAPI IDs following the changes that made it
so that sender_cpu and napi_id were doing a better job of sharing the same
location in the sk_buff.
One issue I found is that we weren't validating the napi_id as being valid
before we started trying to setup the busy polling. This change corrects
that by using the MIN_NAPI_ID value that is now used in both allocating the
NAPI IDs, as well as validating them.
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Fix up affected files that include this signal functionality via sched.h.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We are going to split <linux/sched/clock.h> out of <linux/sched.h>, which
will have to be picked up from other headers and .c files.
Create a trivial placeholder <linux/sched/clock.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Commit 79e7fff47b ("net: remove support for per driver
ndo_busy_poll()") made them obsolete.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
UDP busy polling is restricted to connected UDP sockets.
This is because sk_busy_loop() only takes care of one NAPI context.
There are cases where it could be extended.
1) Some hosts receive traffic on a single NIC, with one RX queue.
2) Some applications use SO_REUSEPORT and associated BPF filter
to split the incoming traffic on one UDP socket per RX
queue/thread/cpu
3) Some UDP sockets are used to send/receive traffic for one flow, but
they do not bother with connect()
This patch records the napi_id of first received skb, giving more
reach to busy polling.
Tested:
lpaa23:~# echo 70 >/proc/sys/net/core/busy_read
lpaa24:~# echo 70 >/proc/sys/net/core/busy_read
lpaa23:~# for f in `seq 1 10`; do ./super_netperf 1 -H lpaa24 -t UDP_RR -l 5; done
Before patch :
27867 28870 37324 41060 41215
36764 36838 44455 41282 43843
After patch :
73920 73213 70147 74845 71697
68315 68028 75219 70082 73707
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Now sk_busy_loop() can schedule by itself, we can remove
need_resched() check from sk_can_busy_loop()
Also add a const to its struct sock parameter.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Adam Belay <abelay@google.com>
Cc: Tariq Toukan <tariqt@mellanox.com>
Cc: Yuval Mintz <Yuval.Mintz@cavium.com>
Cc: Ariel Elior <ariel.elior@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
There is really little gain from inlining this big function.
We'll soon make it even bigger in following patches.
This means we no longer need to export napi_by_id()
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The only valid use of preempt_enable_no_resched() is if the very next
line is schedule() or if we know preemption cannot actually be enabled
by that statement due to known more preempt_count 'refs'.
This busy_poll stuff looks to be completely and utterly broken,
sched_clock() can return utter garbage with interrupts enabled (rare
but still) and it can drift unbounded between CPUs.
This means that if you get preempted/migrated and your new CPU is
years behind on the previous CPU we get to busy spin for a _very_ long
time.
There is a _REASON_ sched_clock() warns about preemptability -
papering over it with a preempt_disable()/preempt_enable_no_resched()
is just terminal brain damage on so many levels.
Replace sched_clock() usage with local_clock() which has a bounded
drift between CPUs (<2 jiffies).
There is a further problem with the entire busy wait poll thing in
that the spin time is additive to the syscall timeout, not inclusive.
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: rui.zhang@intel.com
Cc: jacob.jun.pan@linux.intel.com
Cc: Mike Galbraith <bitbucket@online.de>
Cc: hpa@zytor.com
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: lenb@kernel.org
Cc: rjw@rjwysocki.net
Cc: Eliezer Tamir <eliezer.tamir@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20131119151338.GF3694@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Add a cpu_relaxt to sk_busy_loop.
Julie Cummings reported performance issues when hyperthreading is on.
Arjan van de Ven observed that we should have a cpu_relax() in the
busy poll loop.
Reported-by: Julie Cummings <julie.a.cummings@intel.com>
Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Rename mib counter from "low latency" to "busy poll"
v1 also moved the counter to the ip MIB (suggested by Shawn Bohrer)
Eric Dumazet suggested that the current location is better.
So v2 just renames the counter to fit the new naming convention.
Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
When renaming ll_poll to busy poll, I introduced a typo
in the name of the do-nothing placeholder for sk_busy_loop
and called it sk_busy_poll.
This broke compile when busy poll was not configured.
Cong Wang submitted a patch to fixed that.
This patch removes the now redundant, misspelled placeholder.
Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Eliezer renames several *ll_poll to *busy_poll, but forgets
CONFIG_NET_LL_RX_POLL, so in case of confusion, rename it too.
Cc: Eliezer Tamir <eliezer.tamir@linux.intel.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
When CONFIG_NET_LL_RX_POLL is not set, I got:
net/socket.c: In function ‘sock_poll’:
net/socket.c:1165:4: error: implicit declaration of function ‘sk_busy_loop’ [-Werror=implicit-function-declaration]
Fix this by adding a nop when !CONFIG_NET_LL_RX_POLL.
Cc: Eliezer Tamir <eliezer.tamir@linux.intel.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Rename LL_SO to BUSY_POLL_SO
Rename sysctl_net_ll_{read,poll} to sysctl_busy_{read,poll}
Fix up users of these variables.
Fix documentation for sysctl.
a patch for the socket.7 man page will follow separately,
because of limitations of my mail setup.
Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Rename ndo_ll_poll to ndo_busy_poll.
Rename sk_mark_ll to sk_mark_napi_id.
Rename skb_mark_ll to skb_mark_napi_id.
Correct all useres of these functions.
Update comments and defines in include/net/busy_poll.h
Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Rename the file and correct all the places where it is included.
Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Eric Dumazet
Daniel Borkmann
Björn Töpel
Amritha Nambiar
Thomas Gleixner
Christoph Hellwig
Sridhar Samudrala
Alexander Duyck
Ingo Molnar
Peter Zijlstra
Eliezer Tamir
Cong Wang