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authorTejun Heo <tj@kernel.org>2023-05-08 13:52:27 -1000
committerTejun Heo <tj@kernel.org>2023-05-08 13:52:27 -1000
commit44d69dd9ada17147141c8aa692f044d20bf20107 (patch)
tree41da6c6041683a6fa280e6e554c4b4261eda1cfe
parentbd545224663399435a395b8a4ff2fd4b67892ffa (diff)
greybus: Use alloc_ordered_workqueue() to create ordered workqueues
BACKGROUND ========== When multiple work items are queued to a workqueue, their execution order doesn't match the queueing order. They may get executed in any order and simultaneously. When fully serialized execution - one by one in the queueing order - is needed, an ordered workqueue should be used which can be created with alloc_ordered_workqueue(). However, alloc_ordered_workqueue() was a later addition. Before it, an ordered workqueue could be obtained by creating an UNBOUND workqueue with @max_active==1. This originally was an implementation side-effect which was broken by 4c16bd327c74 ("workqueue: restore WQ_UNBOUND/max_active==1 to be ordered"). Because there were users that depended on the ordered execution, 5c0338c68706 ("workqueue: restore WQ_UNBOUND/max_active==1 to be ordered") made workqueue allocation path to implicitly promote UNBOUND workqueues w/ @max_active==1 to ordered workqueues. While this has worked okay, overloading the UNBOUND allocation interface this way creates other issues. It's difficult to tell whether a given workqueue actually needs to be ordered and users that legitimately want a min concurrency level wq unexpectedly gets an ordered one instead. With planned UNBOUND workqueue updates to improve execution locality and more prevalence of chiplet designs which can benefit from such improvements, this isn't a state we wanna be in forever. This patch series audits all callsites that create an UNBOUND workqueue w/ @max_active==1 and converts them to alloc_ordered_workqueue() as necessary. WHAT TO LOOK FOR ================ The conversions are from alloc_workqueue(WQ_UNBOUND | flags, 1, args..) to alloc_ordered_workqueue(flags, args...) which don't cause any functional changes. If you know that fully ordered execution is not ncessary, please let me know. I'll drop the conversion and instead add a comment noting the fact to reduce confusion while conversion is in progress. If you aren't fully sure, it's completely fine to let the conversion through. The behavior will stay exactly the same and we can always reconsider later. As there are follow-up workqueue core changes, I'd really appreciate if the patch can be routed through the workqueue tree w/ your acks. Thanks. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Acked-by: Johan Hovold <johan@kernel.org> Acked-by: Alex Elder <elder@kernel.org> Cc: greybus-dev@lists.linaro.org
-rw-r--r--drivers/greybus/connection.c4
-rw-r--r--drivers/greybus/svc.c2
2 files changed, 3 insertions, 3 deletions
diff --git a/drivers/greybus/connection.c b/drivers/greybus/connection.c
index e3799a53a193..9c88861986c8 100644
--- a/drivers/greybus/connection.c
+++ b/drivers/greybus/connection.c
@@ -187,8 +187,8 @@ _gb_connection_create(struct gb_host_device *hd, int hd_cport_id,
spin_lock_init(&connection->lock);
INIT_LIST_HEAD(&connection->operations);
- connection->wq = alloc_workqueue("%s:%d", WQ_UNBOUND, 1,
- dev_name(&hd->dev), hd_cport_id);
+ connection->wq = alloc_ordered_workqueue("%s:%d", 0, dev_name(&hd->dev),
+ hd_cport_id);
if (!connection->wq) {
ret = -ENOMEM;
goto err_free_connection;
diff --git a/drivers/greybus/svc.c b/drivers/greybus/svc.c
index 16cced80867a..0d7e749174a4 100644
--- a/drivers/greybus/svc.c
+++ b/drivers/greybus/svc.c
@@ -1318,7 +1318,7 @@ struct gb_svc *gb_svc_create(struct gb_host_device *hd)
if (!svc)
return NULL;
- svc->wq = alloc_workqueue("%s:svc", WQ_UNBOUND, 1, dev_name(&hd->dev));
+ svc->wq = alloc_ordered_workqueue("%s:svc", 0, dev_name(&hd->dev));
if (!svc->wq) {
kfree(svc);
return NULL;