net: WQ_PERCPU added to alloc_workqueue users

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 consistentcy cannot be addressed without refactoring the API.

alloc_workqueue() treats all queues as per-CPU by default, while unbound
workqueues must opt-in via WQ_UNBOUND.

This default is suboptimal: most workloads benefit from unbound queues,
allowing the scheduler to place worker threads where they’re needed and
reducing noise when CPUs are isolated.

This change adds a new WQ_PERCPU flag at the network subsystem, to explicitly
request the use of the per-CPU behavior. Both flags coexist for one release
cycle to allow callers to transition their calls.

Once migration is complete, WQ_UNBOUND can be removed and unbound will
become the implicit default.

With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND),
any alloc_workqueue() caller that doesn’t explicitly specify WQ_UNBOUND
must now use WQ_PERCPU.

All existing users have been updated accordingly.

Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
Link: https://patch.msgid.link/20250918142427.309519-4-marco.crivellari@suse.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

5 files changed, 11 insertions, 7 deletions

diff --git a/drivers/net/ethernet/cavium/liquidio/lio_core.c b/drivers/net/ethernet/cavium/liquidio/lio_core.c
index 674c54831875..215dac201b4a 100644
--- a/drivers/net/ethernet/cavium/liquidio/lio_core.c
+++ b/drivers/net/ethernet/cavium/liquidio/lio_core.c
@@ -472,7 +472,7 @@ int setup_rx_oom_poll_fn(struct net_device *netdev)
 		q_no = lio->linfo.rxpciq[q].s.q_no;
 		wq = &lio->rxq_status_wq[q_no];
 		wq->wq = alloc_workqueue("rxq-oom-status",
-					 WQ_MEM_RECLAIM, 0);
+					 WQ_MEM_RECLAIM | WQ_PERCPU, 0);
 		if (!wq->wq) {
 			dev_err(&oct->pci_dev->dev, "unable to create cavium rxq oom status wq\n");
 			return -ENOMEM;
diff --git a/drivers/net/ethernet/cavium/liquidio/lio_main.c b/drivers/net/ethernet/cavium/liquidio/lio_main.c
index 1d79f6eaa41f..8e2fcec26ea1 100644
--- a/drivers/net/ethernet/cavium/liquidio/lio_main.c
+++ b/drivers/net/ethernet/cavium/liquidio/lio_main.c
@@ -526,7 +526,8 @@ static inline int setup_link_status_change_wq(struct net_device *netdev)
 	struct octeon_device *oct = lio->oct_dev;
 
 	lio->link_status_wq.wq = alloc_workqueue("link-status",
-						 WQ_MEM_RECLAIM, 0);
+						 WQ_MEM_RECLAIM | WQ_PERCPU,
+						 0);
 	if (!lio->link_status_wq.wq) {
 		dev_err(&oct->pci_dev->dev, "unable to create cavium link status wq\n");
 		return -1;
@@ -659,7 +660,8 @@ static inline int setup_sync_octeon_time_wq(struct net_device *netdev)
 	struct octeon_device *oct = lio->oct_dev;
 
 	lio->sync_octeon_time_wq.wq =
-		alloc_workqueue("update-octeon-time", WQ_MEM_RECLAIM, 0);
+		alloc_workqueue("update-octeon-time",
+				WQ_MEM_RECLAIM | WQ_PERCPU, 0);
 	if (!lio->sync_octeon_time_wq.wq) {
 		dev_err(&oct->pci_dev->dev, "Unable to create wq to update octeon time\n");
 		return -1;
@@ -1734,7 +1736,7 @@ static inline int setup_tx_poll_fn(struct net_device *netdev)
 	struct octeon_device *oct = lio->oct_dev;
 
 	lio->txq_status_wq.wq = alloc_workqueue("txq-status",
-						WQ_MEM_RECLAIM, 0);
+						WQ_MEM_RECLAIM | WQ_PERCPU, 0);
 	if (!lio->txq_status_wq.wq) {
 		dev_err(&oct->pci_dev->dev, "unable to create cavium txq status wq\n");
 		return -1;
diff --git a/drivers/net/ethernet/cavium/liquidio/lio_vf_main.c b/drivers/net/ethernet/cavium/liquidio/lio_vf_main.c
index 62c2eadc33e3..3230dff5ba05 100644
--- a/drivers/net/ethernet/cavium/liquidio/lio_vf_main.c
+++ b/drivers/net/ethernet/cavium/liquidio/lio_vf_main.c
@@ -304,7 +304,8 @@ static int setup_link_status_change_wq(struct net_device *netdev)
 	struct octeon_device *oct = lio->oct_dev;
 
 	lio->link_status_wq.wq = alloc_workqueue("link-status",
-						 WQ_MEM_RECLAIM, 0);
+						 WQ_MEM_RECLAIM | WQ_PERCPU,
+						 0);
 	if (!lio->link_status_wq.wq) {
 		dev_err(&oct->pci_dev->dev, "unable to create cavium link status wq\n");
 		return -1;
diff --git a/drivers/net/ethernet/cavium/liquidio/request_manager.c b/drivers/net/ethernet/cavium/liquidio/request_manager.c
index 12105ffb5dac..d7cfb20eea00 100644
--- a/drivers/net/ethernet/cavium/liquidio/request_manager.c
+++ b/drivers/net/ethernet/cavium/liquidio/request_manager.c
@@ -132,7 +132,7 @@ int octeon_init_instr_queue(struct octeon_device *oct,
 	oct->fn_list.setup_iq_regs(oct, iq_no);
 
 	oct->check_db_wq[iq_no].wq = alloc_workqueue("check_iq_db",
-						     WQ_MEM_RECLAIM,
+						     WQ_MEM_RECLAIM | WQ_PERCPU,
 						     0);
 	if (!oct->check_db_wq[iq_no].wq) {
 		vfree(iq->request_list);
diff --git a/drivers/net/ethernet/cavium/liquidio/response_manager.c b/drivers/net/ethernet/cavium/liquidio/response_manager.c
index 861050966e18..de1a8335b545 100644
--- a/drivers/net/ethernet/cavium/liquidio/response_manager.c
+++ b/drivers/net/ethernet/cavium/liquidio/response_manager.c
@@ -39,7 +39,8 @@ int octeon_setup_response_list(struct octeon_device *oct)
 	}
 	spin_lock_init(&oct->cmd_resp_wqlock);
 
-	oct->dma_comp_wq.wq = alloc_workqueue("dma-comp", WQ_MEM_RECLAIM, 0);
+	oct->dma_comp_wq.wq = alloc_workqueue("dma-comp",
+					      WQ_MEM_RECLAIM | WQ_PERCPU, 0);
 	if (!oct->dma_comp_wq.wq) {
 		dev_err(&oct->pci_dev->dev, "failed to create wq thread\n");
 		return -ENOMEM;