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Ido Schimmel 0fb288559c nexthop: Make nexthop bucket dump more efficient
commit f10d3d9df4 upstream.

rtm_dump_nexthop_bucket_nh() is used to dump nexthop buckets belonging
to a specific resilient nexthop group. The function returns a positive
return code (the skb length) upon both success and failure.

The above behavior is problematic. When a complete nexthop bucket dump
is requested, the function that walks the different nexthops treats the
non-zero return code as an error. This causes buckets belonging to
different resilient nexthop groups to be dumped using different buffers
even if they can all fit in the same buffer:

 # ip link add name dummy1 up type dummy
 # ip nexthop add id 1 dev dummy1
 # ip nexthop add id 10 group 1 type resilient buckets 1
 # ip nexthop add id 20 group 1 type resilient buckets 1
 # strace -e recvmsg -s 0 ip nexthop bucket
 [...]
 recvmsg(3, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[...], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 64
 id 10 index 0 idle_time 10.27 nhid 1
 [...]
 recvmsg(3, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[...], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 64
 id 20 index 0 idle_time 6.44 nhid 1
 [...]

Fix by only returning a non-zero return code when an error occurred and
restarting the dump from the bucket index we failed to fill in. This
allows buckets belonging to different resilient nexthop groups to be
dumped using the same buffer:

 # ip link add name dummy1 up type dummy
 # ip nexthop add id 1 dev dummy1
 # ip nexthop add id 10 group 1 type resilient buckets 1
 # ip nexthop add id 20 group 1 type resilient buckets 1
 # strace -e recvmsg -s 0 ip nexthop bucket
 [...]
 recvmsg(3, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[...], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 128
 id 10 index 0 idle_time 30.21 nhid 1
 id 20 index 0 idle_time 26.7 nhid 1
 [...]

While this change is more of a performance improvement change than an
actual bug fix, it is a prerequisite for a subsequent patch that does
fix a bug.

Fixes: 8a1bbabb03 ("nexthop: Add netlink handlers for bucket dump")
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20230808075233.3337922-3-idosch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2023-08-16 18:32:28 +02:00
arch KVM: arm64: Fix hardware enable/disable flows for pKVM 2023-08-16 18:32:23 +02:00
block blk-mq: Fix stall due to recursive flush plug 2023-08-03 10:25:41 +02:00
certs KEYS: Add missing function documentation 2023-04-24 16:15:52 +03:00
crypto crypto: jitter - correct health test during initialization 2023-07-19 16:36:19 +02:00
Documentation Documentation: kdump: Add va_kernel_pa_offset for RISCV64 2023-08-11 12:14:19 +02:00
drivers net: enetc: reimplement RFS/RSS memory clearing as PCI quirk 2023-08-16 18:32:28 +02:00
fs nilfs2: fix use-after-free of nilfs_root in dirtying inodes via iput 2023-08-16 18:32:20 +02:00
include wifi: cfg80211: fix sband iftype data lookup for AP_VLAN 2023-08-16 18:32:27 +02:00
init init, x86: Move mem_encrypt_init() into arch_cpu_finalize_init() 2023-08-08 20:04:49 +02:00
io_uring io_uring: correct check for O_TMPFILE 2023-08-16 18:32:19 +02:00
ipc Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2023-02-24 19:20:07 -08:00
kernel bpf: Disable preemption in bpf_event_output 2023-08-11 12:14:22 +02:00
lib debugobjects: Recheck debug_objects_enabled before reporting 2023-08-11 12:14:25 +02:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm: memory-failure: avoid false hwpoison page mapped error info 2023-08-16 18:32:20 +02:00
net nexthop: Make nexthop bucket dump more efficient 2023-08-16 18:32:28 +02:00
rust rust: allocator: Prevent mis-aligned allocation 2023-08-11 12:14:18 +02:00
samples samples: ftrace: Save required argument registers in sample trampolines 2023-07-23 13:54:09 +02:00
scripts kbuild: rust: avoid creating temporary files 2023-07-27 08:57:06 +02:00
security security: keys: Modify mismatched function name 2023-07-27 08:56:59 +02:00
sound ASoC: wm8904: Fill the cache for WM8904_ADC_TEST_0 register 2023-08-03 10:26:12 +02:00
tools nexthop: Fix infinite nexthop dump when using maximum nexthop ID 2023-08-16 18:32:28 +02:00
usr initramfs: Check negative timestamp to prevent broken cpio archive 2023-04-16 17:37:01 +09:00
virt KVM: Grab a reference to KVM for VM and vCPU stats file descriptors 2023-08-03 10:26:01 +02:00
.clang-format cxl for v6.4 2023-04-30 11:51:51 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for *.dtso files 2023-02-26 15:28:23 +09:00
.gitignore linux-kselftest-kunit-6.4-rc1 2023-04-24 12:31:32 -07:00
.mailmap mailmap: add entries for Ben Dooks 2023-06-19 13:19:35 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: sctp: move Neil to CREDITS 2023-05-12 08:51:32 +01:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Networking fixes for 6.4-rc8, including fixes from ipsec, bpf, 2023-06-22 17:59:51 -07:00
Makefile Linux 6.4.10 2023-08-11 12:14:29 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.