Merge patch series "replace old wq(s), added WQ_PERCPU to alloc_workqueue"

Marco Crivellari <marco.crivellari@suse.com> says:

Hi,

=== Current situation: problems ===

Let's consider a nohz_full system with isolated CPUs: wq_unbound_cpumask is
set to the housekeeping CPUs, for !WQ_UNBOUND the local CPU is selected.

This leads to different scenarios if a work item is scheduled on an
isolated CPU where "delay" value is 0 or greater then 0:
        schedule_delayed_work(, 0);

This will be handled by __queue_work() that will queue the work item on the
current local (isolated) CPU, while:

        schedule_delayed_work(, 1);

Will move the timer on an housekeeping CPU, and schedule the work there.

Currently if a user enqueue a work item using schedule_delayed_work() the
used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
schedule_work() that is using system_wq and queue_work(), that makes use
again of WORK_CPU_UNBOUND.

This lack of consistency cannot be addressed without refactoring the API.

=== Recent changes to the WQ API ===

The following, address the recent changes in the Workqueue API:

- commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq")
- commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag")

The old workqueues will be removed in a future release cycle.

=== Introduced Changes by this series ===

1) [P 1]  Replace uses of system_wq and system_unbound_wq

    system_unbound_wq is to be used when locality is not required.

    Because of that, system_unbound_wq has been replaced with
	system_dfl_wq, to make clear it should be used when locality
	is not required.

2) [P 2-3-4] WQ_PERCPU added to alloc_workqueue()

    This change adds a new WQ_PERCPU flag to explicitly request
    alloc_workqueue() to be per-cpu when WQ_UNBOUND has not been specified.

Thanks!

Link: https://patch.msgid.link/20251031095643.74246-1-marco.crivellari@suse.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --cc drivers/scsi/lpfc/lpfc_init.c
Simple merge

diff --cc drivers/scsi/qla2xxx/qla_os.c
Simple merge

diff --cc drivers/target/target_core_transport.c
Simple merge