Fix build of net/core/stream.o when CONFIG_INET is not enabled.
Fixes these build errors (sample):

ld: net/core/stream.o: in function `sk_stream_write_space':
(.text+0x27e): undefined reference to `tcp_stream_memory_free'
ld: (.text+0x29c): undefined reference to `tcp_stream_memory_free'
ld: (.text+0x2ab): undefined reference to `tcp_stream_memory_free'
ld: net/core/stream.o: in function `sk_stream_wait_memory':
(.text+0x5a1): undefined reference to `tcp_stream_memory_free'
ld: (.text+0x5bf): undefined reference to `tcp_stream_memory_free'

Fixes: 1c5f2ced ("tcp: avoid indirect call to tcp_stream_memory_free()")
Signed-off-by: NRandy Dunlap <rdunlap@infradead.org>
Reported-by: NRandy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20201118194438.674-1-rdunlap@infradead.orgSigned-off-by: NJakub Kicinski <kuba@kernel.org>

The static checker is fooled by the non-static locking scheme
implemented by the mentioned helpers.
Let's make its life easier adding some unconditional annotation
so that the helpers are now interpreted as a plain spinlock from
sparse.

v1 -> v2:
 - add __releases() annotation to unlock_sock_fast()
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Link: https://lore.kernel.org/r/6ed7ae627d8271fb7f20e0a9c6750fbba1ac2635.1605634911.git.pabeni@redhat.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>

Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

This patch added a new helper sk_stop_timer_sync, it deactivates a timer
like sk_stop_timer, but waits for the handler to finish.
Acked-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NGeliang Tang <geliangtang@gmail.com>
Reviewed-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

SOCK_QUEUE_SHRUNK is currently used by TCP as a temporary state
that remembers if some room has been made in the rtx queue
by an incoming ACK packet.

This is later used from tcp_check_space() before
considering to send EPOLLOUT.

Problem is: If we receive SACK packets, and no packet
is removed from RTX queue, we can send fresh packets, thus
moving them from write queue to rtx queue and eventually
empty the write queue.

This stall can happen if TCP_NOTSENT_LOWAT is used.

With this fix, we no longer risk stalling sends while holes
are repaired, and we can fully use socket sndbuf.

This also removes a cache line dirtying for typical RPC
workloads.

Fixes: c9bee3b7 ("tcp: TCP_NOTSENT_LOWAT socket option")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: NNeal Cardwell <ncardwell@google.com>
Acked-by: NSoheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This is a pure codestyle cleanup patch. No functional change intended.
Signed-off-by: NMiaohe Lin <linmiaohe@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

A purely mechanical change to split the renaming from the actual
generalization.

Flags/consts:

  SK_STORAGE_CREATE_FLAG_MASK	BPF_LOCAL_STORAGE_CREATE_FLAG_MASK
  BPF_SK_STORAGE_CACHE_SIZE	BPF_LOCAL_STORAGE_CACHE_SIZE
  MAX_VALUE_SIZE		BPF_LOCAL_STORAGE_MAX_VALUE_SIZE

Structs:

  bucket			bpf_local_storage_map_bucket
  bpf_sk_storage_map		bpf_local_storage_map
  bpf_sk_storage_data		bpf_local_storage_data
  bpf_sk_storage_elem		bpf_local_storage_elem
  bpf_sk_storage		bpf_local_storage

The "sk" member in bpf_local_storage is also updated to "owner"
in preparation for changing the type to void * in a subsequent patch.

Functions:

  selem_linked_to_sk			selem_linked_to_storage
  selem_alloc				bpf_selem_alloc
  __selem_unlink_sk			bpf_selem_unlink_storage_nolock
  __selem_link_sk			bpf_selem_link_storage_nolock
  selem_unlink_sk			__bpf_selem_unlink_storage
  sk_storage_update			bpf_local_storage_update
  __sk_storage_lookup			bpf_local_storage_lookup
  bpf_sk_storage_map_free		bpf_local_storage_map_free
  bpf_sk_storage_map_alloc		bpf_local_storage_map_alloc
  bpf_sk_storage_map_alloc_check	bpf_local_storage_map_alloc_check
  bpf_sk_storage_map_check_btf		bpf_local_storage_map_check_btf
Signed-off-by: NKP Singh <kpsingh@google.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200825182919.1118197-2-kpsingh@chromium.org

This patch adds a new socket helper function to set the mark value for a
kernel socket.
Signed-off-by: NAlexander Aring <aahringo@redhat.com>
Signed-off-by: NDavid Teigland <teigland@redhat.com>

Rework the remaining setsockopt code to pass a sockptr_t instead of a
plain user pointer.  This removes the last remaining set_fs(KERNEL_DS)
outside of architecture specific code.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Acked-by: Stefan Schmidt <stefan@datenfreihafen.org> [ieee802154]
Acked-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Pass a sockptr_t to prepare for set_fs-less handling of the kernel
pointer from bpf-cgroup.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Just check for a NULL method instead of wiring up
sock_no_{get,set}sockopt.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NMarc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Handle the few cases that need special treatment in-line using
in_compat_syscall().  This also removes all the now unused
compat_{get,set}sockopt methods.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add the compat handling to sock_common_{get,set}sockopt instead,
keyed of in_compat_syscall().  This allow to remove the now unused
->compat_{get,set}sockopt methods from struct proto_ops.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Acked-by: NStefan Schmidt <stefan@datenfreihafen.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add missed sock updates to compat path via a new helper, which will be
used more in coming patches. (The net/core/scm.c code is left as-is here
to assist with -stable backports for the compat path.)

Cc: Christoph Hellwig <hch@lst.de>
Cc: Sargun Dhillon <sargun@sargun.me>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: stable@vger.kernel.org
Fixes: 48a87cc2 ("net: netprio: fd passed in SCM_RIGHTS datagram not set correctly")
Fixes: d8429506 ("net: net_cls: fd passed in SCM_RIGHTS datagram not set correctly")
Acked-by: NChristian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: NKees Cook <keescook@chromium.org>

bpf_sk_reuseport_detach is currently called when sk->sk_user_data
is not NULL.  It is incorrect because sk->sk_user_data may not be
managed by the bpf's reuseport_array.  It has been reported in [1] that,
the bpf_sk_reuseport_detach() which is called from udp_lib_unhash() has
corrupted the sk_user_data managed by l2tp.

This patch solves it by using another bit (defined as SK_USER_DATA_BPF)
of the sk_user_data pointer value.  It marks that a sk_user_data is
managed/owned by BPF.

The patch depends on a PTRMASK introduced in
commit f1ff5ce2 ("net, sk_msg: Clear sk_user_data pointer on clone if tagged").

[ Note: sk->sk_user_data is used by bpf's reuseport_array only when a sk is
  added to the bpf's reuseport_array.
  i.e. doing setsockopt(SO_REUSEPORT) and having "sk->sk_reuseport == 1"
  alone will not stop sk->sk_user_data being used by other means. ]

[1]: https://lore.kernel.org/netdev/20200706121259.GA20199@katalix.com/

Fixes: 5dc4c4b7 ("bpf: Introduce BPF_MAP_TYPE_REUSEPORT_SOCKARRAY")
Reported-by: NJames Chapman <jchapman@katalix.com>
Reported-by: syzbot+9f092552ba9a5efca5df@syzkaller.appspotmail.com
Signed-off-by: NMartin KaFai Lau <kafai@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Tested-by: NJames Chapman <jchapman@katalix.com>
Acked-by: NJames Chapman <jchapman@katalix.com>
Link: https://lore.kernel.org/bpf/20200709061110.4019316-1-kafai@fb.com

This is preparation for usage in bpf_setsockopt.
Signed-off-by: NDmitry Yakunin <zeil@yandex-team.ru>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200620153052.9439-1-zeil@yandex-team.ru

Clearing the sock TX queue in sk_set_socket() might cause unexpected
out-of-order transmit when called from sock_orphan(), as outstanding
packets can pick a different TX queue and bypass the ones already queued.

This is undesired in general. More specifically, it breaks the in-order
scheduling property guarantee for device-offloaded TLS sockets.

Remove the call to sk_tx_queue_clear() in sk_set_socket(), and add it
explicitly only where needed.

Fixes: e022f0b4 ("net: Introduce sk_tx_queue_mapping")
Signed-off-by: NTariq Toukan <tariqt@mellanox.com>
Reviewed-by: NBoris Pismenny <borisp@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The sock_bindtoindex intended for kernel wide usage however
it will lock the socket regardless of the context. This modification
relax this behavior optionally: locking the socket will be optional
by calling the sock_bindtoindex with lock_sk = true.

The modification applied to all users of the sock_bindtoindex.
Signed-off-by: NFerenc Fejes <fejes@inf.elte.hu>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/bee6355da40d9e991b2f2d12b67d55ebb5f5b207.1590871065.git.fejes@inf.elte.hu

The SCTP protocol allows to bind multiple address to a socket.  That
feature is currently only exposed as a socket option.  Add a bind_add
method struct proto that allows to bind additional addresses, and
switch the dlm code to use the method instead of going through the
socket option from kernel space.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NMarcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add a helper to directly set the SO_REUSEPORT sockopt from kernel space
without going through a fake uaccess.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add a helper to directly set the SO_RCVBUFFORCE sockopt from kernel space
without going through a fake uaccess.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add a helper to directly set the SO_KEEPALIVE sockopt from kernel space
without going through a fake uaccess.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add a helper to directly enable timestamps instead of setting the
SO_TIMESTAMP* sockopts from kernel space and going through a fake
uaccess.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add a helper to directly set the SO_BINDTOIFINDEX sockopt from kernel
space without going through a fake uaccess.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add a helper to directly set the SO_SNDTIMEO_NEW sockopt from kernel
space without going through a fake uaccess.  The interface is
simplified to only pass the seconds value, as that is the only
thing needed at the moment.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add a helper to directly set the SO_PRIORITY sockopt from kernel space
without going through a fake uaccess.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NSagi Grimberg <sagi@grimberg.me>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add a helper to directly set the SO_LINGER sockopt from kernel space
with onoff set to true and a linger time of 0 without going through a
fake uaccess.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NSagi Grimberg <sagi@grimberg.me>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add a helper to directly set the SO_REUSEADDR sockopt from kernel space
without going through a fake uaccess.

For this the iscsi target now has to formally depend on inet to avoid
a mostly theoretical compile failure.  For actual operation it already
did depend on having ipv4 or ipv6 support.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NSagi Grimberg <sagi@grimberg.me>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Fix warnings related to kernel-doc notation, and wording in
function description.
Signed-off-by: NLothar Rubusch <l.rubusch@gmail.com>
Acked-by: NRandy Dunlap <rdunlap@infradead.org>
Tested-by: NRandy Dunlap <rdunlap@infradead.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Avoid taking a reference on listen sockets by checking the socket type
in the sk_assign and in the corresponding skb_steal_sock() code in the
the transport layer, and by ensuring that the prefetch free (sock_pfree)
function uses the same logic to check whether the socket is refcounted.
Suggested-by: NMartin KaFai Lau <kafai@fb.com>
Signed-off-by: NJoe Stringer <joe@wand.net.nz>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200329225342.16317-4-joe@wand.net.nz

Refactor the UDP/TCP handlers slightly to allow skb_steal_sock() to make
the determination of whether the socket is reference counted in the case
where it is prefetched by earlier logic such as early_demux.
Signed-off-by: NJoe Stringer <joe@wand.net.nz>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200329225342.16317-3-joe@wand.net.nz

Add support for TPROXY via a new bpf helper, bpf_sk_assign().

This helper requires the BPF program to discover the socket via a call
to bpf_sk*_lookup_*(), then pass this socket to the new helper. The
helper takes its own reference to the socket in addition to any existing
reference that may or may not currently be obtained for the duration of
BPF processing. For the destination socket to receive the traffic, the
traffic must be routed towards that socket via local route. The
simplest example route is below, but in practice you may want to route
traffic more narrowly (eg by CIDR):

  $ ip route add local default dev lo

This patch avoids trying to introduce an extra bit into the skb->sk, as
that would require more invasive changes to all code interacting with
the socket to ensure that the bit is handled correctly, such as all
error-handling cases along the path from the helper in BPF through to
the orphan path in the input. Instead, we opt to use the destructor
variable to switch on the prefetch of the socket.
Signed-off-by: NJoe Stringer <joe@wand.net.nz>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200329225342.16317-2-joe@wand.net.nz

sk_user_data can hold a pointer to an object that is not intended to be
shared between the parent socket and the child that gets a pointer copy on
clone. This is the case when sk_user_data points at reference-counted
object, like struct sk_psock.

One way to resolve it is to tag the pointer with a no-copy flag by
repurposing its lowest bit. Based on the bit-flag value we clear the child
sk_user_data pointer after cloning the parent socket.

The no-copy flag is stored in the pointer itself as opposed to externally,
say in socket flags, to guarantee that the pointer and the flag are copied
from parent to child socket in an atomic fashion. Parent socket state is
subject to change while copying, we don't hold any locks at that time.

This approach relies on an assumption that sk_user_data holds a pointer to
an object aligned at least 2 bytes. A manual audit of existing users of
rcu_dereference_sk_user_data helper confirms our assumption.

Also, an RCU-protected sk_user_data is not likely to hold a pointer to a
char value or a pathological case of "struct { char c; }". To be safe, warn
when the flag-bit is set when setting sk_user_data to catch any future
misuses.

It is worth considering why clearing sk_user_data unconditionally is not an
option. There exist users, DRBD, NVMe, and Xen drivers being among them,
that rely on the pointer being copied when cloning the listening socket.

Potentially we could distinguish these users by checking if the listening
socket has been created in kernel-space via sock_create_kern, and hence has
sk_kern_sock flag set. However, this is not the case for NVMe and Xen
drivers, which create sockets without marking them as belonging to the
kernel.
Signed-off-by: NJakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200218171023.844439-3-jakub@cloudflare.com

Fix all kernel-doc warnings for <net/sock.h>.
Fixes these warnings:

../include/net/sock.h:232: warning: Function parameter or member 'skc_addrpair' not described in 'sock_common'
../include/net/sock.h:232: warning: Function parameter or member 'skc_portpair' not described in 'sock_common'
../include/net/sock.h:232: warning: Function parameter or member 'skc_ipv6only' not described in 'sock_common'
../include/net/sock.h:232: warning: Function parameter or member 'skc_net_refcnt' not described in 'sock_common'
../include/net/sock.h:232: warning: Function parameter or member 'skc_v6_daddr' not described in 'sock_common'
../include/net/sock.h:232: warning: Function parameter or member 'skc_v6_rcv_saddr' not described in 'sock_common'
../include/net/sock.h:232: warning: Function parameter or member 'skc_cookie' not described in 'sock_common'
../include/net/sock.h:232: warning: Function parameter or member 'skc_listener' not described in 'sock_common'
../include/net/sock.h:232: warning: Function parameter or member 'skc_tw_dr' not described in 'sock_common'
../include/net/sock.h:232: warning: Function parameter or member 'skc_rcv_wnd' not described in 'sock_common'
../include/net/sock.h:232: warning: Function parameter or member 'skc_tw_rcv_nxt' not described in 'sock_common'

../include/net/sock.h:498: warning: Function parameter or member 'sk_rx_skb_cache' not described in 'sock'
../include/net/sock.h:498: warning: Function parameter or member 'sk_wq_raw' not described in 'sock'
../include/net/sock.h:498: warning: Function parameter or member 'tcp_rtx_queue' not described in 'sock'
../include/net/sock.h:498: warning: Function parameter or member 'sk_tx_skb_cache' not described in 'sock'
../include/net/sock.h:498: warning: Function parameter or member 'sk_route_forced_caps' not described in 'sock'
../include/net/sock.h:498: warning: Function parameter or member 'sk_txtime_report_errors' not described in 'sock'
../include/net/sock.h:498: warning: Function parameter or member 'sk_validate_xmit_skb' not described in 'sock'
../include/net/sock.h:498: warning: Function parameter or member 'sk_bpf_storage' not described in 'sock'

../include/net/sock.h:2024: warning: No description found for return value of 'sk_wmem_alloc_get'
../include/net/sock.h:2035: warning: No description found for return value of 'sk_rmem_alloc_get'
../include/net/sock.h:2046: warning: No description found for return value of 'sk_has_allocations'
../include/net/sock.h:2082: warning: No description found for return value of 'skwq_has_sleeper'
../include/net/sock.h:2244: warning: No description found for return value of 'sk_page_frag'
../include/net/sock.h:2444: warning: Function parameter or member 'tcp_rx_skb_cache_key' not described in 'DECLARE_STATIC_KEY_FALSE'
../include/net/sock.h:2444: warning: Excess function parameter 'sk' description in 'DECLARE_STATIC_KEY_FALSE'
../include/net/sock.h:2444: warning: Excess function parameter 'skb' description in 'DECLARE_STATIC_KEY_FALSE'
Signed-off-by: NRandy Dunlap <rdunlap@infradead.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

XDP sockets use the default implementation of struct sock's
sk_data_ready callback, which is sock_def_readable(). This function
is called in the XDP socket fast-path, and involves a retpoline. By
letting sock_def_readable() have external linkage, and being called
directly, the retpoline can be avoided.
Signed-off-by: NBjörn Töpel <bjorn.topel@intel.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200120092917.13949-1-bjorn.topel@gmail.com

Otherwise we will find stray/unexpected/old extensions value on next
iteration.

On tcp_write_xmit() we can end-up splitting an already queued skb in two
parts, via tso_fragment(). The newly created skb can be allocated via
the tx cache and an upper layer will not be aware of it, so that upper
layer cannot set the ext properly.

Resetting the ext on recycle ensures that stale data is not propagated
in to packet headers or elsewhere.

An alternative would be add an additional hook in tso_fragment() or in
sk_stream_alloc_skb() to init the ext for upper layers that need it.
Co-developed-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Reviewed-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Match the 16-bit width of skbuff->protocol. Fills an 8-bit hole so
sizeof(struct sock) does not change.

Also take care of BPF field access for sk_type/sk_protocol. Both of them
are now outside the bitfield, so we can use load instructions without
further shifting/masking.

v5 -> v6:
 - update eBPF accessors, too (Intel's kbuild test robot)
v2 -> v3:
 - keep 'sk_type' 2 bytes aligned (Eric)
v1 -> v2:
 - preserve sk_pacing_shift as bit field (Eric)

Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: bpf@vger.kernel.org
Co-developed-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Co-developed-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

SK_PROTOCOL_MAX is only used in two places, for DECNet and AX.25. The
limits have more to do with the those protocol definitions than they do
with the data type of sk_protocol, so remove SK_PROTOCOL_MAX and use
U8_MAX directly.
Reviewed-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

sk->sk_pacing_shift can be read and written without lock
synchronization. This patch adds annotations to
document this fact and avoid future syzbot complains.

This might also avoid unexpected false sharing
in sk_pacing_shift_update(), as the compiler
could remove the conditional check and always
write over sk->sk_pacing_shift :

if (sk->sk_pacing_shift != val)
	sk->sk_pacing_shift = val;
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Michal Kubecek and Firo Yang did a very nice analysis of crashes
happening in __inet_lookup_established().

Since a TCP socket can go from TCP_ESTABLISH to TCP_LISTEN
(via a close()/socket()/listen() cycle) without a RCU grace period,
I should not have changed listeners linkage in their hash table.

They must use the nulls protocol (Documentation/RCU/rculist_nulls.txt),
so that a lookup can detect a socket in a hash list was moved in
another one.

Since we added code in commit d296ba60 ("soreuseport: Resolve
merge conflict for v4/v6 ordering fix"), we have to add
hlist_nulls_add_tail_rcu() helper.

Fixes: 3b24d854 ("tcp/dccp: do not touch listener sk_refcnt under synflood")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reported-by: NMichal Kubecek <mkubecek@suse.cz>
Reported-by: NFiro Yang <firo.yang@suse.com>
Reviewed-by: NMichal Kubecek <mkubecek@suse.cz>
Link: https://lore.kernel.org/netdev/20191120083919.GH27852@unicorn.suse.cz/Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>