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Linux kernel for uConsole
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Paolo Abeni 396244b6ec pktgen: do not sleep with the thread lock held. 
[ Upstream commit 720f1de402 ]

Currently, the process issuing a "start" command on the pktgen procfs
interface, acquires the pktgen thread lock and never release it, until
all pktgen threads are completed. The above can blocks indefinitely any
other pktgen command and any (even unrelated) netdevice removal - as
the pktgen netdev notifier acquires the same lock.

The issue is demonstrated by the following script, reported by Matteo:

ip -b - <<'EOF'
	link add type dummy
	link add type veth
	link set dummy0 up
EOF
modprobe pktgen
echo reset >/proc/net/pktgen/pgctrl
{
	echo rem_device_all
	echo add_device dummy0
} >/proc/net/pktgen/kpktgend_0
echo count 0 >/proc/net/pktgen/dummy0
echo start >/proc/net/pktgen/pgctrl &
sleep 1
rmmod veth

Fix the above releasing the thread lock around the sleep call.

Additionally we must prevent racing with forcefull rmmod - as the
thread lock no more protects from them. Instead, acquire a self-reference
before waiting for any thread. As a side effect, running

rmmod pktgen

while some thread is running now fails with "module in use" error,
before this patch such command hanged indefinitely.

Note: the issue predates the commit reported in the fixes tag, but
this fix can't be applied before the mentioned commit.

v1 -> v2:
 - no need to check for thread existence after flipping the lock,
   pktgen threads are freed only at net exit time
 -

Fixes: 6146e6a43b ("[PKTGEN]: Removes thread_{un,}lock() macros.")
Reported-and-tested-by: Matteo Croce <mcroce@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-11 12:20:49 +02:00
arch x86/kprobes: Set instruction page as executable 2019-06-09 09:17:24 +02:00
block block: sed-opal: fix IOC_OPAL_ENABLE_DISABLE_MBR 2019-05-31 06:46:24 -07:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: ccm - fix incompatibility between "ccm" and "ccm_base" 2019-05-22 07:37:43 +02:00
Documentation doc: Cope with Sphinx logging deprecations 2019-06-09 09:17:21 +02:00
drivers net: sfp: read eeprom in maximum 16 byte increments 2019-06-11 12:20:49 +02:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs Revert "lockd: Show pid of lockd for remote locks" 2019-06-09 09:17:22 +02:00
include net/tls: replace the sleeping lock around RX resync with a bit lock 2019-06-11 12:20:49 +02:00
init jump_label: move 'asm goto' support test to Kconfig 2019-06-04 08:02:34 +02:00
ipc ipc/shm.c: use ERR_CAST() for shm_lock() error return 2018-10-05 16:32:04 -07:00
kernel kernel/signal.c: trace_signal_deliver when signal_group_exit 2019-06-09 09:17:20 +02:00
lib jump_label: move 'asm goto' support test to Kconfig 2019-06-04 08:02:34 +02:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm memcg: make it work on sparse non-0-node systems 2019-06-09 09:17:19 +02:00
net pktgen: do not sleep with the thread lock held. 2019-06-11 12:20:49 +02:00
samples samples: mei: use /dev/mei0 instead of /dev/mei 2019-02-15 08:10:11 +01:00
scripts gcc-plugins: Fix build failures under Darwin host 2019-06-09 09:17:22 +02:00
security evm: check hash algorithm passed to init_desc() 2019-06-09 09:17:21 +02:00
sound ALSA: hda/realtek - Improve the headset mic for Acer Aspire laptops 2019-06-09 09:17:17 +02:00
tools jump_label: move 'asm goto' support test to Kconfig 2019-06-04 08:02:34 +02:00
usr initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
virt KVM: s390: Do not report unusabled IDs via KVM_CAP_MAX_VCPU_ID 2019-06-09 09:17:18 +02:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +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 updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS platform/x86: Add Intel AtomISP2 dummy / power-management driver 2019-04-20 09:16:02 +02:00
Makefile Linux 4.19.49 2019-06-09 09:17:25 +02:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -06:00

README 

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.