[PATCH 02/13] wifi: mwifiex: Use default @max_active for workqueues

[PATCH 02/13] wifi: mwifiex: Use default @max_active for workqueues

[Tejun Heo]

These workqueues only host a single work item and thus doen't need explicit
concurrency limit. Let's use the default @max_active. This doesn't cost
anything and clearly expresses that @max_active doesn't matter.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Amitkumar Karwar <amitkarwar@gmail.com>
Cc: Ganapathi Bhat <ganapathi017@gmail.com>
Cc: Sharvari Harisangam <sharvari.harisangam@nxp.com>
Cc: Xinming Hu <huxinming820@gmail.com>
Cc: Kalle Valo <kvalo@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
 drivers/net/wireless/marvell/mwifiex/cfg80211.c | 4 ++--
 drivers/net/wireless/marvell/mwifiex/main.c     | 8 ++++----
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/net/wireless/marvell/mwifiex/cfg80211.c b/drivers/net/wireless/marvell/mwifiex/cfg80211.c
index bcd564dc3554..5337ee4b6f10 100644
--- a/drivers/net/wireless/marvell/mwifiex/cfg80211.c
+++ b/drivers/net/wireless/marvell/mwifiex/cfg80211.c
@@ -3127,7 +3127,7 @@ struct wireless_dev *mwifiex_add_virtual_intf(struct wiphy *wiphy,
 	priv->dfs_cac_workqueue = alloc_workqueue("MWIFIEX_DFS_CAC%s",
 						  WQ_HIGHPRI |
 						  WQ_MEM_RECLAIM |
-						  WQ_UNBOUND, 1, name);
+						  WQ_UNBOUND, 0, name);
 	if (!priv->dfs_cac_workqueue) {
 		mwifiex_dbg(adapter, ERROR, "cannot alloc DFS CAC queue\n");
 		ret = -ENOMEM;
@@ -3138,7 +3138,7 @@ struct wireless_dev *mwifiex_add_virtual_intf(struct wiphy *wiphy,
 
 	priv->dfs_chan_sw_workqueue = alloc_workqueue("MWIFIEX_DFS_CHSW%s",
 						      WQ_HIGHPRI | WQ_UNBOUND |
-						      WQ_MEM_RECLAIM, 1, name);
+						      WQ_MEM_RECLAIM, 0, name);
 	if (!priv->dfs_chan_sw_workqueue) {
 		mwifiex_dbg(adapter, ERROR, "cannot alloc DFS channel sw queue\n");
 		ret = -ENOMEM;
diff --git a/drivers/net/wireless/marvell/mwifiex/main.c b/drivers/net/wireless/marvell/mwifiex/main.c
index ea22a08e6c08..1cd9d20cca16 100644
--- a/drivers/net/wireless/marvell/mwifiex/main.c
+++ b/drivers/net/wireless/marvell/mwifiex/main.c
@@ -1547,7 +1547,7 @@ mwifiex_reinit_sw(struct mwifiex_adapter *adapter)
 
 	adapter->workqueue =
 		alloc_workqueue("MWIFIEX_WORK_QUEUE",
-				WQ_HIGHPRI | WQ_MEM_RECLAIM | WQ_UNBOUND, 1);
+				WQ_HIGHPRI | WQ_MEM_RECLAIM | WQ_UNBOUND, 0);
 	if (!adapter->workqueue)
 		goto err_kmalloc;
 
@@ -1557,7 +1557,7 @@ mwifiex_reinit_sw(struct mwifiex_adapter *adapter)
 		adapter->rx_workqueue = alloc_workqueue("MWIFIEX_RX_WORK_QUEUE",
 							WQ_HIGHPRI |
 							WQ_MEM_RECLAIM |
-							WQ_UNBOUND, 1);
+							WQ_UNBOUND, 0);
 		if (!adapter->rx_workqueue)
 			goto err_kmalloc;
 		INIT_WORK(&adapter->rx_work, mwifiex_rx_work_queue);
@@ -1702,7 +1702,7 @@ mwifiex_add_card(void *card, struct completion *fw_done,
 
 	adapter->workqueue =
 		alloc_workqueue("MWIFIEX_WORK_QUEUE",
-				WQ_HIGHPRI | WQ_MEM_RECLAIM | WQ_UNBOUND, 1);
+				WQ_HIGHPRI | WQ_MEM_RECLAIM | WQ_UNBOUND, 0);
 	if (!adapter->workqueue)
 		goto err_kmalloc;
 
@@ -1712,7 +1712,7 @@ mwifiex_add_card(void *card, struct completion *fw_done,
 		adapter->rx_workqueue = alloc_workqueue("MWIFIEX_RX_WORK_QUEUE",
 							WQ_HIGHPRI |
 							WQ_MEM_RECLAIM |
-							WQ_UNBOUND, 1);
+							WQ_UNBOUND, 0);
 		if (!adapter->rx_workqueue)
 			goto err_kmalloc;
 
-- 
2.40.1

Re: [PATCH 02/13] wifi: mwifiex: Use default @max_active for workqueues

[Kalle Valo]

Tejun Heo <tj@kernel.org> wrote:

> These workqueues only host a single work item and thus doen't need explicit
> concurrency limit. Let's use the default @max_active. This doesn't cost
> anything and clearly expresses that @max_active doesn't matter.
> 
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Cc: Amitkumar Karwar <amitkarwar@gmail.com>
> Cc: Ganapathi Bhat <ganapathi017@gmail.com>
> Cc: Sharvari Harisangam <sharvari.harisangam@nxp.com>
> Cc: Xinming Hu <huxinming820@gmail.com>
> Cc: Kalle Valo <kvalo@kernel.org>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: linux-wireless@vger.kernel.org
> Cc: netdev@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org

I didn't review the patch but I assume it's ok. Feel free to take it via your
tree:

Acked-by: Kalle Valo <kvalo@kernel.org>

Patch set to Not Applicable.

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20230509015032.3768622-3-tj@kernel.org/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

Re: [PATCH 02/13] wifi: mwifiex: Use default @max_active for workqueues

[Brian Norris]

On Mon, May 08, 2023 at 03:50:21PM -1000, Tejun Heo wrote:
> These workqueues only host a single work item and thus doen't need explicit
> concurrency limit. Let's use the default @max_active. This doesn't cost
> anything and clearly expresses that @max_active doesn't matter.
> 
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Cc: Amitkumar Karwar <amitkarwar@gmail.com>
> Cc: Ganapathi Bhat <ganapathi017@gmail.com>
> Cc: Sharvari Harisangam <sharvari.harisangam@nxp.com>
> Cc: Xinming Hu <huxinming820@gmail.com>
> Cc: Kalle Valo <kvalo@kernel.org>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: linux-wireless@vger.kernel.org
> Cc: netdev@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org

Reviewed-by: Brian Norris <briannorris@chromium.org>

I'll admit, the workqueue documentation sounds a bit like "max_active ==
1 + WQ_UNBOUND" is what we want ("one work item [...] active at any
given time"), but that's more of my misunderstanding than anything --
each work item can only be active in a single context at any given time,
so that note is talking about distinct (i.e., more than 1) work items.

While I'm here: we're still debugging what's affecting WiFi performance
on some of our WiFi systems, but it's possible I'll be turning some of
these into struct kthread_worker instead. We can cross that bridge
(including potential conflicts) if/when we come to it though.

Thanks,
Brian

Re: [PATCH 02/13] wifi: mwifiex: Use default @max_active for workqueues

[Tejun Heo]

Hello,

On Wed, May 10, 2023 at 11:09:55AM -0700, Brian Norris wrote:
> I'll admit, the workqueue documentation sounds a bit like "max_active ==
> 1 + WQ_UNBOUND" is what we want ("one work item [...] active at any
> given time"), but that's more of my misunderstanding than anything --
> each work item can only be active in a single context at any given time,
> so that note is talking about distinct (i.e., more than 1) work items.

Yeah, a future patch is gonna change the semantics a bit and I'll update the
doc to be clearer.

> While I'm here: we're still debugging what's affecting WiFi performance
> on some of our WiFi systems, but it's possible I'll be turning some of
> these into struct kthread_worker instead. We can cross that bridge
> (including potential conflicts) if/when we come to it though.

Can you elaborate the performance problem you're seeing? I'm working on a
major update for workqueue to improve its locality behavior, so if you're
experiencing issues on CPUs w/ multiple L3 caches, it'd be a good test case.

Thanks.

-- 
tejun

Re: [PATCH 02/13] wifi: mwifiex: Use default @max_active for workqueues

[Brian Norris]

Hi,

On Wed, May 10, 2023 at 08:16:00AM -1000, Tejun Heo wrote:
> > While I'm here: we're still debugging what's affecting WiFi performance
> > on some of our WiFi systems, but it's possible I'll be turning some of
> > these into struct kthread_worker instead. We can cross that bridge
> > (including potential conflicts) if/when we come to it though.
> 
> Can you elaborate the performance problem you're seeing? I'm working on a
> major update for workqueue to improve its locality behavior, so if you're
> experiencing issues on CPUs w/ multiple L3 caches, it'd be a good test case.

Sure!

Test case: iperf TCP RX (i.e., hits "MWIFIEX_RX_WORK_QUEUE" a lot) at
some of the higher (VHT 80 MHz) data rates.

Hardware: Mediatek MT8173 2xA53 (little) + 2xA72 (big) CPU
(I'm not familiar with its cache details)
+
Marvell SD8897 SDIO WiFi (mwifiex_sdio)

We're looking at a major regression from our 4.19 kernel to a 5.15
kernel (yeah, that's downstream reality). So far, we've found that
performance is:

(1) much better (nearly the same as 4.19) if we add WQ_SYSFS and pin the
work queue to one CPU (doesn't really matter which CPU, as long as it's
not the one loaded with IRQ(?) work)

(2) moderately better if we pin the CPU frequency (e.g., "performance"
cpufreq governor instead of "schedutil")

(3) moderately better (not quite as good as (2)) if we switch a
kthread_worker and don't pin anything.

We tried (2) because we saw a lot more CPU migration on kernel 5.15
(work moves across all 4 CPUs throughout the run; on kernel 4.19 it
mostly switched between 2 CPUs).

We tried (3) suspecting some kind of EAS issue (instead of distributing
our workload onto 4 different kworkers, our work (and therefore our load
calculation) is mostly confined to a single kernel thread). But it still
seems like our issues are more than "just" EAS / cpufreq issues, since
(2) and (3) aren't as good as (1).

NB: there weren't many relevant mwifiex or MTK-SDIO changes in this
range.

So we're still investigating a few other areas, but it does seem like
"locality" (in some sense of the word) is relevant. We'd probably be
open to testing any patches you have, although it's likely we'd have the
easiest time if we can port those to 5.15. We're constantly working on
getting good upstream support for Chromebook chips, but ARM SoC reality
is that it still varies a lot as to how much works upstream on any given
system.

Thanks,
Brian

Re: [PATCH 02/13] wifi: mwifiex: Use default @max_active for workqueues

[Tejun Heo]

Hello,

On Wed, May 10, 2023 at 11:57:41AM -0700, Brian Norris wrote:
> Test case: iperf TCP RX (i.e., hits "MWIFIEX_RX_WORK_QUEUE" a lot) at
> some of the higher (VHT 80 MHz) data rates.
> 
> Hardware: Mediatek MT8173 2xA53 (little) + 2xA72 (big) CPU
> (I'm not familiar with its cache details)
> +
> Marvell SD8897 SDIO WiFi (mwifiex_sdio)

Yeah, we had multiple of similar cases on, what I think are, similar
configurations, which is why I'm working on improving workqueue locality.

> We're looking at a major regression from our 4.19 kernel to a 5.15
> kernel (yeah, that's downstream reality). So far, we've found that
> performance is:

That's curious. 4.19 is old but I scanned the history and there's nothing
which can cause that kind of perf regression for unbound workqueues between
4.19 and 5.15.

> (1) much better (nearly the same as 4.19) if we add WQ_SYSFS and pin the
> work queue to one CPU (doesn't really matter which CPU, as long as it's
> not the one loaded with IRQ(?) work)
> 
> (2) moderately better if we pin the CPU frequency (e.g., "performance"
> cpufreq governor instead of "schedutil")
> 
> (3) moderately better (not quite as good as (2)) if we switch a
> kthread_worker and don't pin anything.

Hmm... so it's not just workqueue.

> We tried (2) because we saw a lot more CPU migration on kernel 5.15
> (work moves across all 4 CPUs throughout the run; on kernel 4.19 it
> mostly switched between 2 CPUs).

Workqueue can contribute to this but it seems more likely that scheduling
changes are also part of the story.

> We tried (3) suspecting some kind of EAS issue (instead of distributing
> our workload onto 4 different kworkers, our work (and therefore our load
> calculation) is mostly confined to a single kernel thread). But it still
> seems like our issues are more than "just" EAS / cpufreq issues, since
> (2) and (3) aren't as good as (1).
> 
> NB: there weren't many relevant mwifiex or MTK-SDIO changes in this
> range.
> 
> So we're still investigating a few other areas, but it does seem like
> "locality" (in some sense of the word) is relevant. We'd probably be
> open to testing any patches you have, although it's likely we'd have the
> easiest time if we can port those to 5.15. We're constantly working on
> getting good upstream support for Chromebook chips, but ARM SoC reality
> is that it still varies a lot as to how much works upstream on any given
> system.

I should be able to post the patchset later today or tomorrow. It comes with
sysfs knobs to control affinity scopes and strictness, so hopefully you
should be able to find the configuration that works without too much
difficulty.

Thanks.

-- 
tejun

Re: [PATCH 02/13] wifi: mwifiex: Use default @max_active for workqueues

[Brian Norris]

On Wed, May 10, 2023 at 09:19:20AM -1000, Tejun Heo wrote:
> On Wed, May 10, 2023 at 11:57:41AM -0700, Brian Norris wrote:
> > (1) much better (nearly the same as 4.19) if we add WQ_SYSFS and pin the
> > work queue to one CPU (doesn't really matter which CPU, as long as it's
> > not the one loaded with IRQ(?) work)
> > 
> > (2) moderately better if we pin the CPU frequency (e.g., "performance"
> > cpufreq governor instead of "schedutil")
> > 
> > (3) moderately better (not quite as good as (2)) if we switch a
> > kthread_worker and don't pin anything.
> 
> Hmm... so it's not just workqueue.

Right. And not just cpufreq either.

> > We tried (2) because we saw a lot more CPU migration on kernel 5.15
> > (work moves across all 4 CPUs throughout the run; on kernel 4.19 it
> > mostly switched between 2 CPUs).
> 
> Workqueue can contribute to this but it seems more likely that scheduling
> changes are also part of the story.

Yeah, that's one theory. And in that vein, that's one reason we might
consider switching to a kthread_worker anyway, even if that doesn't
solve all the regression -- because schedutil relies on per-entity load
calculations to make decisions, and workqueues don't help the scheduler
understand that load when spread across N CPUs (workers). A dedicated
kthread would better represent our workload to the scheduler.

(Threaded NAPI -- mwifiex doesn't support NAPI -- takes a similar
approach, as it has its own thread per NAPI context.)

> > We tried (3) suspecting some kind of EAS issue (instead of distributing
> > our workload onto 4 different kworkers, our work (and therefore our load
> > calculation) is mostly confined to a single kernel thread). But it still
> > seems like our issues are more than "just" EAS / cpufreq issues, since
> > (2) and (3) aren't as good as (1).
> > 
> > NB: there weren't many relevant mwifiex or MTK-SDIO changes in this
> > range.
> > 
> > So we're still investigating a few other areas, but it does seem like
> > "locality" (in some sense of the word) is relevant. We'd probably be
> > open to testing any patches you have, although it's likely we'd have the
> > easiest time if we can port those to 5.15. We're constantly working on
> > getting good upstream support for Chromebook chips, but ARM SoC reality
> > is that it still varies a lot as to how much works upstream on any given
> > system.
> 
> I should be able to post the patchset later today or tomorrow. It comes with
> sysfs knobs to control affinity scopes and strictness, so hopefully you
> should be able to find the configuration that works without too much
> difficulty.

Great!

Brian

Re: [PATCH 02/13] wifi: mwifiex: Use default @max_active for workqueues

[Tejun Heo]

On Mon, May 08, 2023 at 03:50:21PM -1000, Tejun Heo wrote:
> These workqueues only host a single work item and thus doen't need explicit
> concurrency limit. Let's use the default @max_active. This doesn't cost
> anything and clearly expresses that @max_active doesn't matter.

Applied to wq/for-6.5-cleanup-ordered.

Thanks.

-- 
tejun

[PATCH 05/13] wifi: ath10/11/12k: Use alloc_ordered_workqueue() to create ordered workqueues

[Tejun Heo]

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>
Cc: Kalle Valo <kvalo@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
---
 drivers/net/wireless/ath/ath10k/qmi.c | 3 +--
 drivers/net/wireless/ath/ath11k/qmi.c | 3 +--
 drivers/net/wireless/ath/ath12k/qmi.c | 3 +--
 3 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/net/wireless/ath/ath10k/qmi.c b/drivers/net/wireless/ath/ath10k/qmi.c
index 038c5903c0dc..52c1a3de8da6 100644
--- a/drivers/net/wireless/ath/ath10k/qmi.c
+++ b/drivers/net/wireless/ath/ath10k/qmi.c
@@ -1082,8 +1082,7 @@ int ath10k_qmi_init(struct ath10k *ar, u32 msa_size)
 	if (ret)
 		goto err;
 
-	qmi->event_wq = alloc_workqueue("ath10k_qmi_driver_event",
-					WQ_UNBOUND, 1);
+	qmi->event_wq = alloc_ordered_workqueue("ath10k_qmi_driver_event", 0);
 	if (!qmi->event_wq) {
 		ath10k_err(ar, "failed to allocate workqueue\n");
 		ret = -EFAULT;
diff --git a/drivers/net/wireless/ath/ath11k/qmi.c b/drivers/net/wireless/ath/ath11k/qmi.c
index ab923e24b0a9..26b252e62909 100644
--- a/drivers/net/wireless/ath/ath11k/qmi.c
+++ b/drivers/net/wireless/ath/ath11k/qmi.c
@@ -3256,8 +3256,7 @@ int ath11k_qmi_init_service(struct ath11k_base *ab)
 		return ret;
 	}
 
-	ab->qmi.event_wq = alloc_workqueue("ath11k_qmi_driver_event",
-					   WQ_UNBOUND, 1);
+	ab->qmi.event_wq = alloc_ordered_workqueue("ath11k_qmi_driver_event", 0);
 	if (!ab->qmi.event_wq) {
 		ath11k_err(ab, "failed to allocate workqueue\n");
 		return -EFAULT;
diff --git a/drivers/net/wireless/ath/ath12k/qmi.c b/drivers/net/wireless/ath/ath12k/qmi.c
index 03ba245fbee9..0a7892b1a8f8 100644
--- a/drivers/net/wireless/ath/ath12k/qmi.c
+++ b/drivers/net/wireless/ath/ath12k/qmi.c
@@ -3056,8 +3056,7 @@ int ath12k_qmi_init_service(struct ath12k_base *ab)
 		return ret;
 	}
 
-	ab->qmi.event_wq = alloc_workqueue("ath12k_qmi_driver_event",
-					   WQ_UNBOUND, 1);
+	ab->qmi.event_wq = alloc_ordered_workqueue("ath12k_qmi_driver_event", 0);
 	if (!ab->qmi.event_wq) {
 		ath12k_err(ab, "failed to allocate workqueue\n");
 		return -EFAULT;
-- 
2.40.1

Re: [PATCH 05/13] wifi: ath10/11/12k: Use alloc_ordered_workqueue() to create ordered workqueues

[Kalle Valo]

Tejun Heo <tj@kernel.org> wrote:

> 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>
> Cc: Kalle Valo <kvalo@kernel.org>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: linux-wireless@vger.kernel.org
> Cc: netdev@vger.kernel.org

I run quick smoke tests with ath11k and ath12k, didn't see any issues. Feel
free to take via the workqueue tree:

Acked-by: Kalle Valo <kvalo@kernel.org>

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20230509015032.3768622-6-tj@kernel.org/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

Re: [PATCH 05/13] wifi: ath10/11/12k: Use alloc_ordered_workqueue() to create ordered workqueues

[Tejun Heo]

Applied to wq/for-6.5-cleanup-ordered.

Thanks.

-- 
tejun

[PATCH 06/13] net: wwan: t7xx: Use alloc_ordered_workqueue() to create ordered workqueues

[Tejun Heo]

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>
Cc: Chandrashekar Devegowda <chandrashekar.devegowda@intel.com>
Cc: Intel Corporation <linuxwwan@intel.com>
Cc: Chiranjeevi Rapolu <chiranjeevi.rapolu@linux.intel.com>
Cc: Liu Haijun <haijun.liu@mediatek.com>
Cc: M Chetan Kumar <m.chetan.kumar@linux.intel.com>
Cc: Ricardo Martinez <ricardo.martinez@linux.intel.com>
Cc: Loic Poulain <loic.poulain@linaro.org>
Cc: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: netdev@vger.kernel.org
---
 drivers/net/wwan/t7xx/t7xx_hif_cldma.c     | 13 +++++++------
 drivers/net/wwan/t7xx/t7xx_hif_dpmaif_tx.c |  5 +++--
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/net/wwan/t7xx/t7xx_hif_cldma.c b/drivers/net/wwan/t7xx/t7xx_hif_cldma.c
index aec3a18d44bd..7162bf38a8c9 100644
--- a/drivers/net/wwan/t7xx/t7xx_hif_cldma.c
+++ b/drivers/net/wwan/t7xx/t7xx_hif_cldma.c
@@ -1293,9 +1293,9 @@ int t7xx_cldma_init(struct cldma_ctrl *md_ctrl)
 	for (i = 0; i < CLDMA_TXQ_NUM; i++) {
 		md_cd_queue_struct_init(&md_ctrl->txq[i], md_ctrl, MTK_TX, i);
 		md_ctrl->txq[i].worker =
-			alloc_workqueue("md_hif%d_tx%d_worker",
-					WQ_UNBOUND | WQ_MEM_RECLAIM | (i ? 0 : WQ_HIGHPRI),
-					1, md_ctrl->hif_id, i);
+			alloc_ordered_workqueue("md_hif%d_tx%d_worker",
+					WQ_MEM_RECLAIM | (i ? 0 : WQ_HIGHPRI),
+					md_ctrl->hif_id, i);
 		if (!md_ctrl->txq[i].worker)
 			goto err_workqueue;
 
@@ -1306,9 +1306,10 @@ int t7xx_cldma_init(struct cldma_ctrl *md_ctrl)
 		md_cd_queue_struct_init(&md_ctrl->rxq[i], md_ctrl, MTK_RX, i);
 		INIT_WORK(&md_ctrl->rxq[i].cldma_work, t7xx_cldma_rx_done);
 
-		md_ctrl->rxq[i].worker = alloc_workqueue("md_hif%d_rx%d_worker",
-							 WQ_UNBOUND | WQ_MEM_RECLAIM,
-							 1, md_ctrl->hif_id, i);
+		md_ctrl->rxq[i].worker =
+			alloc_ordered_workqueue("md_hif%d_rx%d_worker",
+						WQ_MEM_RECLAIM,
+						md_ctrl->hif_id, i);
 		if (!md_ctrl->rxq[i].worker)
 			goto err_workqueue;
 	}
diff --git a/drivers/net/wwan/t7xx/t7xx_hif_dpmaif_tx.c b/drivers/net/wwan/t7xx/t7xx_hif_dpmaif_tx.c
index 46514208d4f9..8dab025a088a 100644
--- a/drivers/net/wwan/t7xx/t7xx_hif_dpmaif_tx.c
+++ b/drivers/net/wwan/t7xx/t7xx_hif_dpmaif_tx.c
@@ -618,8 +618,9 @@ int t7xx_dpmaif_txq_init(struct dpmaif_tx_queue *txq)
 		return ret;
 	}
 
-	txq->worker = alloc_workqueue("md_dpmaif_tx%d_worker", WQ_UNBOUND | WQ_MEM_RECLAIM |
-				      (txq->index ? 0 : WQ_HIGHPRI), 1, txq->index);
+	txq->worker = alloc_ordered_workqueue("md_dpmaif_tx%d_worker",
+				WQ_MEM_RECLAIM | (txq->index ? 0 : WQ_HIGHPRI),
+				txq->index);
 	if (!txq->worker)
 		return -ENOMEM;
 
-- 
2.40.1

Re: [PATCH 06/13] net: wwan: t7xx: Use alloc_ordered_workqueue() to create ordered workqueues

[Tejun Heo]

On Mon, May 08, 2023 at 03:50:25PM -1000, Tejun Heo wrote:
...
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Cc: Chandrashekar Devegowda <chandrashekar.devegowda@intel.com>
> Cc: Intel Corporation <linuxwwan@intel.com>
> Cc: Chiranjeevi Rapolu <chiranjeevi.rapolu@linux.intel.com>
> Cc: Liu Haijun <haijun.liu@mediatek.com>
> Cc: M Chetan Kumar <m.chetan.kumar@linux.intel.com>
> Cc: Ricardo Martinez <ricardo.martinez@linux.intel.com>
> Cc: Loic Poulain <loic.poulain@linaro.org>
> Cc: Sergey Ryazanov <ryazanov.s.a@gmail.com>
> Cc: Johannes Berg <johannes@sipsolutions.net>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: netdev@vger.kernel.org

Hey, I'm going to apply this to wq/for-6.5-cleanup-ordered. As it's an
identity conversion, it shouldn't break anything. Please holler if you have
any concerns.

Thanks.

-- 
tejun

[PATCH 09/13] net: qrtr: Use alloc_ordered_workqueue() to create ordered workqueues

[Tejun Heo]

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>
Cc: Manivannan Sadhasivam <mani@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: linux-arm-msm@vger.kernel.org
Cc: netdev@vger.kernel.org
---
 net/qrtr/ns.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/qrtr/ns.c b/net/qrtr/ns.c
index 0f25a386138c..0f7a729f1a1f 100644
--- a/net/qrtr/ns.c
+++ b/net/qrtr/ns.c
@@ -783,7 +783,7 @@ int qrtr_ns_init(void)
 		goto err_sock;
 	}
 
-	qrtr_ns.workqueue = alloc_workqueue("qrtr_ns_handler", WQ_UNBOUND, 1);
+	qrtr_ns.workqueue = alloc_ordered_workqueue("qrtr_ns_handler", 0);
 	if (!qrtr_ns.workqueue) {
 		ret = -ENOMEM;
 		goto err_sock;
-- 
2.40.1

Re: [PATCH 09/13] net: qrtr: Use alloc_ordered_workqueue() to create ordered workqueues

[Tejun Heo]

On Mon, May 08, 2023 at 03:50:28PM -1000, Tejun Heo wrote:
...
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Cc: Manivannan Sadhasivam <mani@kernel.org>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: linux-arm-msm@vger.kernel.org
> Cc: netdev@vger.kernel.org

Hey, I'm going to apply this to wq/for-6.5-cleanup-ordered. As it's an
identity conversion, it shouldn't break anything. Please holler if you have
any concerns.

Thanks.

-- 
tejun

[PATCH 10/13] rxrpc: Use alloc_ordered_workqueue() to create ordered workqueues

[Tejun Heo]

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>
Cc: David Howells <dhowells@redhat.com>
Cc: Marc Dionne <marc.dionne@auristor.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: linux-afs@lists.infradead.org
Cc: netdev@vger.kernel.org
---
 net/rxrpc/af_rxrpc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/rxrpc/af_rxrpc.c b/net/rxrpc/af_rxrpc.c
index 31f738d65f1c..7eb24c25c731 100644
--- a/net/rxrpc/af_rxrpc.c
+++ b/net/rxrpc/af_rxrpc.c
@@ -988,7 +988,7 @@ static int __init af_rxrpc_init(void)
 		goto error_call_jar;
 	}
 
-	rxrpc_workqueue = alloc_workqueue("krxrpcd", WQ_HIGHPRI | WQ_MEM_RECLAIM | WQ_UNBOUND, 1);
+	rxrpc_workqueue = alloc_ordered_workqueue("krxrpcd", WQ_HIGHPRI | WQ_MEM_RECLAIM);
 	if (!rxrpc_workqueue) {
 		pr_notice("Failed to allocate work queue\n");
 		goto error_work_queue;
-- 
2.40.1

Re: [PATCH 10/13] rxrpc: Use alloc_ordered_workqueue() to create ordered workqueues

[Tejun Heo]

On Mon, May 08, 2023 at 03:50:29PM -1000, Tejun Heo wrote:
...
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Cc: David Howells <dhowells@redhat.com>
> Cc: Marc Dionne <marc.dionne@auristor.com>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: linux-afs@lists.infradead.org
> Cc: netdev@vger.kernel.org

Hey, I'm going to apply this to wq/for-6.5-cleanup-ordered. As it's an
identity conversion, it shouldn't break anything. Please holler if you have
any concerns.

Thanks.

-- 
tejun