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Jan Stancek 0dd1e3773a pipe: fix empty pipe check in pipe_write()
LTP pipeio_1 test is hanging with v5.5-rc2-385-gb8e382a185eb,
with read side observing empty pipe and sleeping and write
side running out of space and then sleeping as well. In this
scenario there are 5 writers and 1 reader.

Problem is that after pipe_write() reacquires pipe lock, it
re-checks for empty pipe with potentially stale 'head' and
doesn't wake up read side anymore. pipe->tail can advance
beyond 'head', because there are multiple writers.

Use pipe->head for empty pipe check after reacquiring lock
to observe current state.

Testing: With patch, LTP pipeio_1 ran successfully in loop for 1 hour.
         Without patch it hanged within a minute.

Fixes: 1b6b26ae70 ("pipe: fix and clarify pipe write wakeup logic")
Reported-by: Rachel Sibley <rasibley@redhat.com>
Signed-off-by: Jan Stancek <jstancek@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-12-22 09:47:47 -08:00
arch s390 updates for 5.5-rc3 2019-12-21 12:17:14 -08:00
block for-linus-20191212 2019-12-13 14:27:19 -08:00
certs certs: Add wrapper function to check blacklisted binary hash 2019-11-12 12:25:50 +11:00
crypto tpmdd fixes for Linux v5.5-rc3 2019-12-18 17:17:36 -08:00
Documentation Kbuild fixes for v5.5 2019-12-21 10:49:47 -08:00
drivers xen: branch for v5.5-rc3 2019-12-21 06:24:56 -08:00
fs pipe: fix empty pipe check in pipe_write() 2019-12-22 09:47:47 -08:00
include xen: branch for v5.5-rc3 2019-12-21 06:24:56 -08:00
init early init: fix error handling when opening /dev/console 2019-12-17 13:10:11 -08:00
ipc treewide: Use sizeof_field() macro 2019-12-09 10:36:44 -08:00
kernel Various tracing fixes: 2019-12-21 15:16:56 -08:00
lib lib/Kconfig.debug: fix some messed up configurations 2019-12-17 20:59:59 -08:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm mm: vmscan: protect shrinker idr replace with CONFIG_MEMCG 2019-12-17 20:59:59 -08:00
net io_uring-5.5-20191212 2019-12-13 14:24:54 -08:00
samples samples/trace_printk: Wait for IRQ work to finish 2019-12-21 16:08:22 -05:00
scripts Kbuild fixes for v5.5 2019-12-21 10:49:47 -08:00
security tpmdd fixes for Linux v5.5-rc3 2019-12-18 17:17:36 -08:00
sound sound fixes for 5.5-rc3 2019-12-18 08:54:15 -08:00
tools libnvdimm fix 5.5-rc3 2019-12-21 15:12:26 -08:00
usr kbuild: fix 'No such file or directory' warning when cleaning 2019-12-09 10:08:21 +09:00
virt KVM: Fix jump label out_free_* in kvm_init() 2019-11-23 11:29:17 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig
.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 modpost: dump missing namespaces into a single modules.nsdeps file 2019-11-11 20:10:01 +09:00
.mailmap ARM: SoC fixes 2019-12-16 16:43:07 -08:00
COPYING
CREDITS Linux 5.4-rc4 2019-10-29 04:43:29 -06:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS ARM: SoC fixes 2019-12-16 16:43:07 -08:00
Makefile Kbuild fixes for v5.5 2019-12-21 10:49:47 -08:00
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.