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John Fastabend f0a8c1257f tls: possible hang when do_tcp_sendpages hits sndbuf is full case
[ Upstream commit 67db7cd249 ]

Currently, the lower protocols sk_write_space handler is not called if
TLS is sending a scatterlist via  tls_push_sg. However, normally
tls_push_sg calls do_tcp_sendpage, which may be under memory pressure,
that in turn may trigger a wait via sk_wait_event. Typically, this
happens when the in-flight bytes exceed the sdnbuf size. In the normal
case when enough ACKs are received sk_write_space() will be called and
the sk_wait_event will be woken up allowing it to send more data
and/or return to the user.

But, in the TLS case because the sk_write_space() handler does not
wake up the events the above send will wait until the sndtimeo is
exceeded. By default this is MAX_SCHEDULE_TIMEOUT so it look like a
hang to the user (especially this impatient user). To fix this pass
the sk_write_space event to the lower layers sk_write_space event
which in the TCP case will wake any pending events.

I observed the above while integrating sockmap and ktls. It
initially appeared as test_sockmap (modified to use ktls) occasionally
hanging. To reliably reproduce this reduce the sndbuf size and stress
the tls layer by sending many 1B sends. This results in every byte
needing a header and each byte individually being sent to the crypto
layer.

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Dave Watson <davejwatson@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-10-03 17:00:58 -07:00
arch arm64: KVM: Tighten guest core register access from userspace 2018-10-03 17:00:57 -07:00
block blk-mq: avoid to synchronize rcu inside blk_cleanup_queue() 2018-09-26 08:38:13 +02:00
certs Replace magic for trusting the secondary keyring with #define 2018-09-09 19:55:54 +02:00
crypto crypto: skcipher - Fix -Wstringop-truncation warnings 2018-10-03 17:00:45 -07:00
Documentation inet: frags: break the 2GB limit for frags storage 2018-09-19 22:43:46 +02:00
drivers thermal: of-thermal: disable passive polling when thermal zone is disabled 2018-10-03 17:00:57 -07:00
firmware License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fs isofs: reject hardware sector size > 2048 bytes 2018-10-03 17:00:57 -07:00
include slub: make ->cpu_partial unsigned int 2018-10-03 17:00:55 -07:00
init init: rename and re-order boot_cpu_state_init() 2018-08-15 18:12:48 +02:00
ipc ipc/sem.c: prevent queue.status tearing in semop 2018-09-05 09:26:30 +02:00
kernel module: exclude SHN_UNDEF symbols from kallsyms api 2018-10-03 17:00:53 -07:00
lib scsi: klist: Make it safe to use klists in atomic context 2018-10-03 17:00:48 -07:00
mm slub: make ->cpu_partial unsigned int 2018-10-03 17:00:55 -07:00
net tls: possible hang when do_tcp_sendpages hits sndbuf is full case 2018-10-03 17:00:58 -07:00
samples samples/bpf: Check the error of write() and read() 2018-08-24 13:09:12 +02:00
scripts kbuild: add .DELETE_ON_ERROR special target 2018-09-26 08:37:59 +02:00
security Revert "uapi/linux/keyctl.h: don't use C++ reserved keyword as a struct member name" 2018-09-29 03:06:04 -07:00
sound ASoC: dapm: Fix potential DAI widget pointer deref when linking DAIs 2018-10-03 17:00:53 -07:00
tools selftest: timers: Tweak raw_skew to SKIP when ADJ_OFFSET/other clock adjustments are in progress 2018-09-26 08:38:13 +02:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt KVM: arm/arm64: Fix vgic init race 2018-09-26 08:38:04 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: rpm-pkg: keep spec file until make mrproper 2018-02-13 10:19:46 +01:00
.mailmap .mailmap: Add Maciej W. Rozycki's Imagination e-mail address 2017-11-10 12:16:15 -08:00
COPYING
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS dt-bindings: Document mti,mips-cpc binding 2018-03-15 10:54:35 +01:00
Makefile Linux 4.14.73 2018-09-29 03:06:07 -07:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

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

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

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.