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Marc Kleine-Budde 4eab421bc3 net: sched: Avoid using yield() in a busy waiting loop
With threaded interrupts enabled, the interrupt thread runs as SCHED_RR
with priority 50. If a user application with a higher priority preempts
the interrupt thread and tries to shutdown the network interface then it
will loop forever. The kernel will spin in the loop waiting for the
device to become idle and the scheduler will never consider the
interrupt thread because its priority is lower.

Avoid the problem by sleeping for a jiffy giving other tasks,
including the interrupt thread, a chance to run and make progress.

In the original thread it has been suggested to use wait_event() and
properly waiting for the state to occur. DaveM explained that this would
require to add expensive checks in the fast paths of packet processing.

Link: https://lkml.kernel.org/r/1393976987-23555-1-git-send-email-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
[bigeasy: Rewrite commit message, add comment, use
          schedule_timeout_uninterruptible()]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-10-17 15:33:03 -04:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2019-10-14 12:17:21 -07:00
block block: sed-opal: fix sparse warning: convert __be64 data 2019-10-03 14:21:32 -06:00
certs PKCS#7: Refactor verify_pkcs7_signature() 2019-08-05 18:40:18 -04:00
crypto Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-09-28 08:14:15 -07:00
Documentation Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2019-10-14 12:17:21 -07:00
drivers net: socionext: netsec: fix xdp stats accounting 2019-10-17 15:02:33 -04:00
fs Merge branch 'readdir' (readdir speedup and sanity checking) 2019-10-05 12:03:27 -07:00
include net: sfp: move fwnode parsing into sfp-bus layer 2019-10-16 14:31:59 -04:00
init init: Support mounting root file systems over SMB 2019-10-02 12:15:15 -04:00
ipc ipc/sem.c: convert to use built-in RCU list checking 2019-09-25 17:51:41 -07:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2019-10-14 12:17:21 -07:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-10-05 08:50:15 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm Merge branch 'hugepage-fallbacks' (hugepatch patches from David Rientjes) 2019-09-28 14:26:47 -07:00
net net: sched: Avoid using yield() in a busy waiting loop 2019-10-17 15:33:03 -04:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2019-10-14 12:17:21 -07:00
scripts Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2019-10-14 12:17:21 -07:00
security Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-10-05 13:37:23 -07:00
sound sound fixes for 5.4-rc1 2019-09-24 16:46:16 -07:00
tools tc-testing: updated pedit test cases 2019-10-15 20:35:18 -07:00
usr kbuild: update compile-test header list for v5.4-rc2 2019-10-05 15:29:49 +09:00
virt KVM/arm fixes for 5.4, take #1 2019-10-03 12:08:50 +02:00
.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
.gitignore Modules updates for v5.4 2019-09-22 10:34:46 -07:00
.mailmap Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next 2019-09-18 12:34:53 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS CREDITS: Update email address 2019-09-13 17:21:38 +03:00
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 net: Update address for vrf and l3mdev in MAINTAINERS 2019-10-15 10:56:45 -07:00
Makefile kbuild: remove SUBDIRS support 2019-10-01 09:21:21 +09:00
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.