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Jakub Kicinski 68d676a089 nfp: bpf: don't stop offload if replace failed
Stopping offload completely if replace of program failed dates
back to days of transparent offload.  Back then we wanted to
silently fall back to the in-driver processing.  Today we mark
programs for offload when they are loaded into the kernel, so
the transparent offload is no longer a reality.

Flags check in the driver will only allow replace of a driver
program with another driver program or an offload program with
another offload program.

When driver program is replaced stopping offload is a no-op,
because driver program isn't offloaded.  When replacing
offloaded program if the offload fails the entire operation
will fail all the way back to user space and we should continue
using the old program.  IOW when replacing a driver program
stopping offload is unnecessary and when replacing offloaded
program - it's a bug, old program should continue to run.

In practice this bug would mean that if offload operation was to
fail (either due to FW communication error, kernel OOM or new
program being offloaded but for a different netdev) driver
would continue reporting that previous XDP program is offloaded
but in fact no program will be loaded in hardware.  The failure
is fairly unlikely (found by inspection, when working on the code)
but it's unpleasant.

Backport note: even though the bug was introduced in commit
cafa92ac25 ("nfp: bpf: add support for XDP_FLAGS_HW_MODE"),
this fix depends on commit 441a33031f ("net: xdp: don't allow
device-bound programs in driver mode"), so this fix is sufficient
only in v4.15 or newer.  Kernels v4.13.x and v4.14.x do need to
stop offload if it was transparent/opportunistic, i.e. if
XDP_FLAGS_HW_MODE was not set on running program.

Fixes: cafa92ac25 ("nfp: bpf: add support for XDP_FLAGS_HW_MODE")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-06-25 11:33:55 +02:00
arch Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux 2018-06-19 07:44:51 +09:00
block for-linus-20180616 2018-06-17 05:37:55 +09:00
certs docs: Fix some broken references 2018-06-15 18:10:01 -03:00
crypto docs: Fix some broken references 2018-06-15 18:10:01 -03:00
Documentation Move all the dma-mapping code to kernel/dma 2018-06-20 16:30:01 +09:00
drivers nfp: bpf: don't stop offload if replace failed 2018-06-25 11:33:55 +02:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs proc: fix missing final NUL in get_mm_cmdline() rewrite 2018-06-20 15:38:28 +09:00
include bpf: enforce correct alignment for instructions 2018-06-21 12:46:06 +09:00
init dma-mapping: move all DMA mapping code to kernel/dma 2018-06-14 08:50:37 +02:00
ipc ipc: use new return type vm_fault_t 2018-06-15 07:55:25 +09:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-06-21 07:13:42 +09:00
lib Move all the dma-mapping code to kernel/dma 2018-06-20 16:30:01 +09:00
LICENSES LICENSES: Add Linux-OpenIB license text 2018-04-27 16:41:53 -06:00
mm revert "mm/memblock: add missing include <linux/bootmem.h>" 2018-06-19 07:43:44 +09:00
net sctp: fix erroneous inc of snmp SctpFragUsrMsgs 2018-06-21 12:49:33 +09:00
samples VFIO updates for v4.18 2018-06-12 13:11:26 -07:00
scripts scripts/documentation-file-ref-check: check tools/*/Documentation 2018-06-15 18:10:01 -03:00
security docs: Fix some broken references 2018-06-15 18:10:01 -03:00
sound docs: Fix some broken references 2018-06-15 18:10:01 -03:00
tools tools/bpf: fix test_sockmap failure 2018-06-22 00:31:42 +02:00
usr kbuild: rename built-in.o to built-in.a 2018-03-26 02:01:19 +09:00
virt - Error path bug fix for overflow tests (Dan) 2018-06-12 18:28:00 -07:00
.clang-format clang-format: add configuration file 2018-04-11 10:28:35 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap Merge branch 'asoc-4.17' into asoc-4.18 for compress dependencies 2018-04-26 12:24:28 +01:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS/CREDITS: Drop METAG ARCHITECTURE 2018-03-05 16:34:24 +00:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: add basic helper macros to scripts/Kconfig.include 2018-05-29 03:31:19 +09:00
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-06-21 07:13:42 +09:00
Makefile Linux 4.18-rc1 2018-06-17 08:04:49 +09:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -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.
See Documentation/00-INDEX for a list of what is contained in each file.

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.