linux-stable.git/include/net/tcp.h, branch linux-6.17.y

Merge tag 'kbuild-v6.17-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2025-08-06T04:32:52+00:00

Pull Kbuild updates from Masahiro Yamada:
 "This is the last pull request from me.

  I'm grateful to have been able to continue as a maintainer for eight
  years. From the next cycle, Nathan and Nicolas will maintain Kbuild.

   - Fix a shortcut key issue in menuconfig

   - Fix missing rebuild of kheaders

   - Sort the symbol dump generated by gendwarfsyms

   - Support zboot extraction in scripts/extract-vmlinux

   - Migrate gconfig to GTK 3

   - Add TAR variable to allow overriding the default tar command

   - Hand over Kbuild maintainership"

* tag 'kbuild-v6.17-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (92 commits)
  MAINTAINERS: hand over Kbuild maintenance
  kheaders: make it possible to override TAR
  kbuild: userprogs: use correct linker when mixing clang and GNU ld
  kconfig: lxdialog: replace strcpy() with strncpy() in inputbox.c
  kconfig: lxdialog: replace strcpy with snprintf in print_autowrap
  kconfig: gconf: refactor text_insert_help()
  kconfig: gconf: remove unneeded variable in text_insert_msg
  kconfig: gconf: use hyphens in signals
  kconfig: gconf: replace GtkImageMenuItem with GtkMenuItem
  kconfig: gconf: Fix Back button behavior
  kconfig: gconf: fix single view to display dependent symbols correctly
  scripts: add zboot support to extract-vmlinux
  gendwarfksyms: order -T symtypes output by name
  gendwarfksyms: use preferred form of sizeof for allocation
  kconfig: qconf: confine {begin,end}Group to constructor and destructor
  kconfig: qconf: fix ConfigList::updateListAllforAll()
  kconfig: add a function to dump all menu entries in a tree-like format
  kconfig: gconf: show GTK version in About dialog
  kconfig: gconf: replace GtkHPaned and GtkVPaned with GtkPaned
  kconfig: gconf: replace GdkColor with GdkRGBA
  ...

net: track pfmemalloc drops via SKB_DROP_REASON_PFMEMALLOC

2025-07-18T23:59:05+00:00

Add a new SKB drop reason (SKB_DROP_REASON_PFMEMALLOC) to track packets
dropped due to memory pressure. In production environments, we've observed
memory exhaustion reported by memory layer stack traces, but these drops
were not properly tracked in the SKB drop reason infrastructure.

While most network code paths now properly report pfmemalloc drops, some
protocol-specific socket implementations still use sk_filter() without
drop reason tracking:
- Bluetooth L2CAP sockets
- CAIF sockets
- IUCV sockets
- Netlink sockets
- SCTP sockets
- Unix domain sockets

These remaining cases represent less common paths and could be converted
in a follow-up patch if needed. The current implementation provides
significantly improved observability into memory pressure events in the
network stack, especially for key protocols like TCP and UDP, helping to
diagnose problems in production environments.

Reported-by: Matt Fleming 
Signed-off-by: Jesper Dangaard Brouer 
Link: https://patch.msgid.link/175268316579.2407873.11634752355644843509.stgit@firesoul
Signed-off-by: Jakub Kicinski

tcp: move tcp_memory_allocated into net_aligned_data

2025-07-02T21:22:02+00:00

____cacheline_aligned_in_smp attribute only makes sure to align
a field to a cache line. It does not prevent the linker to use
the remaining of the cache line for other variables, causing
potential false sharing.

Move tcp_memory_allocated into a dedicated cache line.

Signed-off-by: Eric Dumazet 
Reviewed-by: Willem de Bruijn 
Link: https://patch.msgid.link/20250630093540.3052835-4-edumazet@google.com
Signed-off-by: Jakub Kicinski

module: remove meaningless 'name' parameter from __MODULE_INFO()

2025-06-24T11:33:31+00:00

The symbol names in the .modinfo section are never used and already
randomized by the __UNIQUE_ID() macro.

Therefore, the second parameter of  __MODULE_INFO() is meaningless
and can be removed to simplify the code.

With this change, the symbol names in the .modinfo section will be
prefixed with __UNIQUE_ID_modinfo, making it clearer that they
originate from MODULE_INFO().

[Before]

  $ objcopy  -j .modinfo vmlinux.o modinfo.o
  $ nm -n modinfo.o | head -n10
  0000000000000000 r __UNIQUE_ID_license560
  0000000000000011 r __UNIQUE_ID_file559
  0000000000000030 r __UNIQUE_ID_description558
  0000000000000074 r __UNIQUE_ID_license580
  000000000000008e r __UNIQUE_ID_file579
  00000000000000bd r __UNIQUE_ID_description578
  00000000000000e6 r __UNIQUE_ID_license581
  00000000000000ff r __UNIQUE_ID_file580
  0000000000000134 r __UNIQUE_ID_description579
  0000000000000179 r __UNIQUE_ID_uncore_no_discover578

[After]

  $ objcopy  -j .modinfo vmlinux.o modinfo.o
  $ nm -n modinfo.o | head -n10
  0000000000000000 r __UNIQUE_ID_modinfo560
  0000000000000011 r __UNIQUE_ID_modinfo559
  0000000000000030 r __UNIQUE_ID_modinfo558
  0000000000000074 r __UNIQUE_ID_modinfo580
  000000000000008e r __UNIQUE_ID_modinfo579
  00000000000000bd r __UNIQUE_ID_modinfo578
  00000000000000e6 r __UNIQUE_ID_modinfo581
  00000000000000ff r __UNIQUE_ID_modinfo580
  0000000000000134 r __UNIQUE_ID_modinfo579
  0000000000000179 r __UNIQUE_ID_modinfo578

Signed-off-by: Masahiro Yamada 
Reviewed-by: Petr Pavlu

net: tcp: tsq: Convert from tasklet to BH workqueue

2025-06-18T01:29:21+00:00

The only generic interface to execute asynchronously in the BH context is
tasklet; however, it's marked deprecated and has some design flaws. To
replace tasklets, BH workqueue support was recently added. A BH workqueue
behaves similarly to regular workqueues except that the queued work items
are executed in the BH context.

This patch converts TCP Small Queues implementation from tasklet to BH
workqueue.

Semantically, this is an equivalent conversion and there shouldn't be any
user-visible behavior changes. While workqueue's queueing and execution
paths are a bit heavier than tasklet's, unless the work item is being queued
every packet, the difference hopefully shouldn't matter.

My experience with the networking stack is very limited and this patch
definitely needs attention from someone who actually understands networking.

Signed-off-by: Tejun Heo 
Reviewed-by: Jason Xing 
Reviewed-by: Eric Dumazet 
Cc: David Ahern 
Link: https://patch.msgid.link/aFBeJ38AS1ZF3Dq5@slm.duckdns.org
Signed-off-by: Jakub Kicinski

tcp: remove RFC3517/RFC6675 tcp_clear_retrans_hints_partial()

2025-06-17T23:19:04+00:00

Now that we have removed the RFC3517/RFC6675 hints,
tcp_clear_retrans_hints_partial() is empty, and can be removed.

Suggested-by: Yuchung Cheng 
Signed-off-by: Neal Cardwell 
Reviewed-by: Yuchung Cheng 
Reviewed-by: Eric Dumazet 
Link: https://patch.msgid.link/20250615001435.2390793-4-ncardwell.sw@gmail.com
Signed-off-by: Jakub Kicinski

tcp: remove RFC3517/RFC6675 hint state: lost_skb_hint, lost_cnt_hint

2025-06-17T23:19:04+00:00

Now that obsolete RFC3517/RFC6675 TCP loss detection has been removed,
we can remove the somewhat complex and intrusive code to maintain its
hint state: lost_skb_hint and lost_cnt_hint.

This commit makes tcp_clear_retrans_hints_partial() empty. We will
remove tcp_clear_retrans_hints_partial() and its call sites in the
next commit.

Suggested-by: Yuchung Cheng 
Signed-off-by: Neal Cardwell 
Reviewed-by: Yuchung Cheng 
Reviewed-by: Eric Dumazet 
Link: https://patch.msgid.link/20250615001435.2390793-3-ncardwell.sw@gmail.com
Signed-off-by: Jakub Kicinski

tcp: add TCP_RFC7323_TW_PAWS drop reason

2025-04-11T01:29:26+00:00

Devices in the networking path, such as firewalls, NATs, or routers, which
can perform SNAT or DNAT, use addresses from their own limited address
pools to masquerade the source address during forwarding, causing PAWS
verification to fail more easily.

Currently, packet loss statistics for PAWS can only be viewed through MIB,
which is a global metric and cannot be precisely obtained through tracing
to get the specific 4-tuple of the dropped packet. In the past, we had to
use kprobe ret to retrieve relevant skb information from
tcp_timewait_state_process().

We add a drop_reason pointer, similar to what previous commit does:
commit e34100c2ecbb ("tcp: add a drop_reason pointer to tcp_check_req()")

This commit addresses the PAWSESTABREJECTED case and also sets the
corresponding drop reason.

We use 'pwru' to test.

Before this commit:
''''
./pwru 'port 9999'
2025/04/07 13:40:19 Listening for events..
TUPLE                                        FUNC
172.31.75.115:12345->172.31.75.114:9999(tcp) sk_skb_reason_drop(SKB_DROP_REASON_NOT_SPECIFIED)
'''

After this commit:
'''
./pwru 'port 9999'
2025/04/07 13:51:34 Listening for events..
TUPLE                                        FUNC
172.31.75.115:12345->172.31.75.114:9999(tcp) sk_skb_reason_drop(SKB_DROP_REASON_TCP_RFC7323_TW_PAWS)
'''

Suggested-by: Eric Dumazet 
Signed-off-by: Jiayuan Chen 
Reviewed-by: Eric Dumazet 
Link: https://patch.msgid.link/20250409112614.16153-2-jiayuan.chen@linux.dev
Signed-off-by: Jakub Kicinski

Revert "tcp: avoid atomic operations on sk->sk_rmem_alloc"

2025-03-31T23:53:54+00:00

This reverts commit 0de2a5c4b824da2205658ebebb99a55c43cdf60f.

I forgot that a TCP socket could receive messages in its error queue.

sock_queue_err_skb() can be called without socket lock being held,
and changes sk->sk_rmem_alloc.

The fact that skbs in error queue are limited by sk->sk_rcvbuf
means that error messages can be dropped if socket receive
queues are full, which is an orthogonal issue.

In future kernels, we could use a separate sk->sk_error_mem_alloc
counter specifically for the error queue.

Fixes: 0de2a5c4b824 ("tcp: avoid atomic operations on sk->sk_rmem_alloc")
Signed-off-by: Eric Dumazet 
Link: https://patch.msgid.link/20250331075946.31960-1-edumazet@google.com
Signed-off-by: Jakub Kicinski

tcp: avoid atomic operations on sk->sk_rmem_alloc

2025-03-25T14:37:16+00:00

TCP uses generic skb_set_owner_r() and sock_rfree()
for received packets, with socket lock being owned.

Switch to private versions, avoiding two atomic operations
per packet.

Signed-off-by: Eric Dumazet 
Reviewed-by: Neal Cardwell 
Reviewed-by: Kuniyuki Iwashima 
Link: https://patch.msgid.link/20250320121604.3342831-1-edumazet@google.com
Signed-off-by: Jakub Kicinski