The current doc of workqueue API suggests that work items are
non-reentrant: any work item is guaranteed to be executed by at most one
worker system-wide at any given time. However this is not true, the
following case can cause a work item W executed by two workers at
the same time:
queue_work_on(0, WQ1, W);
// after a worker picks up W and clear the pending bit
queue_work_on(1, WQ2, W);
// workers on CPU0 and CPU1 will execute W in the same time.
, which means the non-reentrance of a work item is conditional, and
Lai Jiangshan provided a nice summary[1] of the conditions, therefore
use it to describe a work item instance and improve the doc.
[1]: https://lore.kernel.org/lkml/CAJhGHyDudet_xyNk=8xnuO2==o-u06s0E0GZVP4Q67nmQ84Ceg@mail.gmail.com/
Suggested-by: Matthew Wilcox <willy@infradead.org>
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
As there's already a rst file with workqueue markups, containing
part of them, move the other definitions, in order to avoid
warnings with Sphinx.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Clean up workqueue.rst:
- fix minor typos
- put '@' after `` instead of preceding them (one place)
- use "CPU" instead of "cpu" in text consistently
- quote one function name
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Florian Mickler <florian@mickler.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
NUMA rework of workqueue made the combination of max_active of 1 and
WQ_UNBOUND insufficient to guarantee ST behavior system wide.
alloc_ordered_queue should now be used instead.
Signed-off-by: Alexei Potashnik <alexei@purestorage.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Boqun Feng