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Marc Kleine-Budde 7119d7864b can: dev: always create TX echo skb
So far the creation of the TX echo skb was optional and can be
controlled by the local sender of a CAN frame.

It turns out that the TX echo CAN skb can be piggybacked to carry
information in the driver from the TX- to the TX-complete handler.

Several drivers already use the return value of
can_get_echo_skb() (which is the length of the data field in the CAN
frame) for their number of transferred bytes statistics. The
statistics are not working if CAN echo skbs are disabled.

Another use case is to calculate and set the CAN frame length on the
wire, which is needed for BQL support in both the TX and TX-completion
handler.

For now in can_put_echo_skb(), which is called from the TX handler,
the skb carrying the CAN frame is discarded if no TX echo is
requested, leading to the above illustrated problems.

This patch changes the can_put_echo_skb() function, so that the echo
skb is always generated. If the sender requests no echo, the echo skb
is consumed in __can_get_echo_skb() without being passed into the RX
handler of the networking stack, but the CAN data length and CAN frame
length information is properly returned.

Link: https://lore.kernel.org/r/20210309211904.3348700-1-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
2021-03-30 09:31:54 +02:00
arch Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2021-03-25 16:30:46 -07:00
block block: Discard page cache of zone reset target range 2021-03-11 11:49:25 -07:00
certs certs: Replace K{U,G}IDT_INIT() with GLOBAL_ROOT_{U,G}ID 2021-01-21 16:16:10 +00:00
crypto crypto: mips/poly1305 - enable for all MIPS processors 2021-03-08 11:52:17 +01:00
Documentation Documentation: net: Document resilient next-hop groups 2021-03-29 13:51:38 -07:00
drivers can: dev: always create TX echo skb 2021-03-30 09:31:54 +02:00
fs sysctl: add proc_dou8vec_minmax() 2021-03-25 17:39:33 -07:00
include nexthop: Rename artifacts related to legacy multipath nexthop groups 2021-03-28 17:53:39 -07:00
init Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-03-25 15:31:22 -07:00
ipc fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
kernel sysctl: add proc_dou8vec_minmax() 2021-03-25 17:39:33 -07:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-03-25 15:31:22 -07:00
LICENSES LICENSES: Add the CC-BY-4.0 license 2020-12-08 10:33:27 -07:00
mm Merge branch 'akpm' (patches from Andrew) 2021-03-25 11:43:43 -07:00
net tcp: fix tcp_min_tso_segs sysctl 2021-03-29 16:33:48 -07:00
samples Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2021-03-25 16:30:46 -07:00
scripts Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-03-25 15:31:22 -07:00
security Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-03-25 15:31:22 -07:00
sound sound fixes for 5.12-rc4 2021-03-19 09:53:32 -07:00
tools selftests: mlxsw: Test vetoing of double sampling 2021-03-29 13:37:26 -07:00
usr Kbuild updates for v5.12 2021-02-25 10:17:31 -08:00
virt KVM: x86/mmu: Consider the hva in mmu_notifier retry 2021-02-22 13:16:53 -05:00
.clang-format cxl for 5.12 2021-02-24 09:38:36 -08:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore clang-lto series for v5.12-rc1 2021-02-23 09:28:51 -08:00
.mailmap Merge branch 'akpm' (patches from Andrew) 2021-03-25 11:43:43 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS treewide: Miguel has moved 2021-02-26 09:41:03 -08:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: Update MCAN MMIO device driver maintainer 2021-03-30 09:31:54 +02:00
Makefile Linux 5.12-rc4 2021-03-21 14:56:43 -07:00
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.