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 <[email protected]>
Cc: Amitkumar Karwar <[email protected]>
Cc: Ganapathi Bhat <[email protected]>
Cc: Sharvari Harisangam <[email protected]>
Cc: Xinming Hu <[email protected]>
Cc: Kalle Valo <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Paolo Abeni <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
---
.../net/wireless/marvell/mwifiex/cfg80211.c | 13 +++++------
drivers/net/wireless/marvell/mwifiex/main.c | 22 +++++++++----------
2 files changed, 16 insertions(+), 19 deletions(-)
diff --git a/drivers/net/wireless/marvell/mwifiex/cfg80211.c b/drivers/net/wireless/marvell/mwifiex/cfg80211.c
index bcd564dc3554..5a7be57ed78a 100644
--- a/drivers/net/wireless/marvell/mwifiex/cfg80211.c
+++ b/drivers/net/wireless/marvell/mwifiex/cfg80211.c
@@ -3124,10 +3124,9 @@ struct wireless_dev *mwifiex_add_virtual_intf(struct wiphy *wiphy,
SET_NETDEV_DEV(dev, adapter->dev);
- priv->dfs_cac_workqueue = alloc_workqueue("MWIFIEX_DFS_CAC%s",
- WQ_HIGHPRI |
- WQ_MEM_RECLAIM |
- WQ_UNBOUND, 1, name);
+ priv->dfs_cac_workqueue =
+ alloc_ordered_workqueue("MWIFIEX_DFS_CAC%s",
+ WQ_HIGHPRI | WQ_MEM_RECLAIM, name);
if (!priv->dfs_cac_workqueue) {
mwifiex_dbg(adapter, ERROR, "cannot alloc DFS CAC queue\n");
ret = -ENOMEM;
@@ -3136,9 +3135,9 @@ struct wireless_dev *mwifiex_add_virtual_intf(struct wiphy *wiphy,
INIT_DELAYED_WORK(&priv->dfs_cac_work, mwifiex_dfs_cac_work_queue);
- priv->dfs_chan_sw_workqueue = alloc_workqueue("MWIFIEX_DFS_CHSW%s",
- WQ_HIGHPRI | WQ_UNBOUND |
- WQ_MEM_RECLAIM, 1, name);
+ priv->dfs_chan_sw_workqueue =
+ alloc_ordered_workqueue("MWIFIEX_DFS_CHSW%s",
+ WQ_HIGHPRI | WQ_MEM_RECLAIM, 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..19a6107d115c 100644
--- a/drivers/net/wireless/marvell/mwifiex/main.c
+++ b/drivers/net/wireless/marvell/mwifiex/main.c
@@ -1546,18 +1546,17 @@ mwifiex_reinit_sw(struct mwifiex_adapter *adapter)
adapter->rx_work_enabled = true;
adapter->workqueue =
- alloc_workqueue("MWIFIEX_WORK_QUEUE",
- WQ_HIGHPRI | WQ_MEM_RECLAIM | WQ_UNBOUND, 1);
+ alloc_ordered_workqueue("MWIFIEX_WORK_QUEUE",
+ WQ_HIGHPRI | WQ_MEM_RECLAIM);
if (!adapter->workqueue)
goto err_kmalloc;
INIT_WORK(&adapter->main_work, mwifiex_main_work_queue);
if (adapter->rx_work_enabled) {
- adapter->rx_workqueue = alloc_workqueue("MWIFIEX_RX_WORK_QUEUE",
- WQ_HIGHPRI |
- WQ_MEM_RECLAIM |
- WQ_UNBOUND, 1);
+ adapter->rx_workqueue =
+ alloc_ordered_workqueue("MWIFIEX_RX_WORK_QUEUE",
+ WQ_HIGHPRI | WQ_MEM_RECLAIM);
if (!adapter->rx_workqueue)
goto err_kmalloc;
INIT_WORK(&adapter->rx_work, mwifiex_rx_work_queue);
@@ -1701,18 +1700,17 @@ mwifiex_add_card(void *card, struct completion *fw_done,
adapter->rx_work_enabled = true;
adapter->workqueue =
- alloc_workqueue("MWIFIEX_WORK_QUEUE",
- WQ_HIGHPRI | WQ_MEM_RECLAIM | WQ_UNBOUND, 1);
+ alloc_ordered_workqueue("MWIFIEX_WORK_QUEUE",
+ WQ_HIGHPRI | WQ_MEM_RECLAIM);
if (!adapter->workqueue)
goto err_kmalloc;
INIT_WORK(&adapter->main_work, mwifiex_main_work_queue);
if (adapter->rx_work_enabled) {
- adapter->rx_workqueue = alloc_workqueue("MWIFIEX_RX_WORK_QUEUE",
- WQ_HIGHPRI |
- WQ_MEM_RECLAIM |
- WQ_UNBOUND, 1);
+ adapter->rx_workqueue =
+ alloc_ordered_workqueue("MWIFIEX_RX_WORK_QUEUE",
+ WQ_HIGHPRI | WQ_MEM_RECLAIM);
if (!adapter->rx_workqueue)
goto err_kmalloc;
--
2.40.0
On Thu, Apr 20, 2023 at 04:50:34PM -1000, Tejun Heo wrote:
> 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 <[email protected]>
> Cc: Amitkumar Karwar <[email protected]>
> Cc: Ganapathi Bhat <[email protected]>
> Cc: Sharvari Harisangam <[email protected]>
> Cc: Xinming Hu <[email protected]>
> Cc: Kalle Valo <[email protected]>
> Cc: "David S. Miller" <[email protected]>
> Cc: Eric Dumazet <[email protected]>
> Cc: Jakub Kicinski <[email protected]>
> Cc: Paolo Abeni <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
> ---
> .../net/wireless/marvell/mwifiex/cfg80211.c | 13 +++++------
> drivers/net/wireless/marvell/mwifiex/main.c | 22 +++++++++----------
> 2 files changed, 16 insertions(+), 19 deletions(-)
These work queues only ever get a single work item on them, so
"ordering" can't really matter. This could go either way -- a comment or
the current patch; so:
Reviewed-by: Brian Norris <[email protected]>
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 <[email protected]>
Cc: Amitkumar Karwar <[email protected]>
Cc: Ganapathi Bhat <[email protected]>
Cc: Sharvari Harisangam <[email protected]>
Cc: Xinming Hu <[email protected]>
Cc: Kalle Valo <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Paolo Abeni <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
---
Hello, Brian.
Do you mind acking this patch instead?
Thanks.
drivers/net/wireless/marvell/mwifiex/cfg80211.c | 4 ++--
drivers/net/wireless/marvell/mwifiex/main.c | 8 ++++----
2 files changed, 6 insertions(+), 6 deletions(-)
--- 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
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
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;
--- 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->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->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 comp
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 comp
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;