[PATCH net-next v5 0/6] net: napi: add CPU affinity to napi->config

[PATCH net-next v5 0/6] net: napi: add CPU affinity to napi->config

[Ahmed Zaki]

Drivers usually need to re-apply the user-set IRQ affinity to their IRQs
after reset. However, since there can be only one IRQ affinity notifier
for each IRQ, registering IRQ notifiers conflicts with the ARFS rmap
management in the core (which also registers separate IRQ affinity
notifiers).   

Move the IRQ affinity management to the napi struct. This way we can have
a unified IRQ notifier to re-apply the user-set affinity and also manage
the ARFS rmaps. Patches 1 and 2 move the ARFS rmap management to CORE.
Patch 3 adds the IRQ affinity mask to napi_config and re-applies the mask
after reset. Patches 4-6 use the new API for bnxt, ice and idpf drivers.

Tested on bnxt, ice and idpf.

V5:
    - Add kernel doc for new netdev flags (Simon).
    - Remove defensive (if !napi) check in napi_irq_cpu_rmap_add()
      (patch 2) since caller is already dereferencing the pointer (Simon).
    - Fix build error when CONFIG_ARFS_ACCEL is not defined (patch 3).

v4:
    - https://lore.kernel.org/netdev/20250109233107.17519-1-ahmed.zaki@intel.com/
    - Better introduction in the cover letter.
    - Fix Kernel build errors in ena_init_rx_cpu_rmap() (Patch 1)
    - Fix kernel test robot warnings reported by Dan Carpenter:
      https://lore.kernel.org/all/202501050625.nY1c97EX-lkp@intel.com/
    - Remove unrelated empty line in patch 4 (Kalesh Anakkur Purayil)
    - Fix a memleak (rmap was not freed) by calling cpu_rmap_put() in
      netif_napi_affinity_release() (patch 2).

v3:
    - https://lore.kernel.org/netdev/20250104004314.208259-1-ahmed.zaki@intel.com/
    - Assign one cpu per mask starting from local NUMA node (Shay Drori).
    - Keep the new ARFS and Affinity flags per nedev (Jakub).

v2:
    - https://lore.kernel.org/netdev/202412190454.nwvp3hU2-lkp@intel.com/T/
    - Also move the ARFS IRQ affinity management from drivers to core. Via
      netif_napi_set_irq(), drivers can ask the core to add the IRQ to the
      ARFS rmap (already allocated by the driver).

RFC -> v1:
    - https://lore.kernel.org/netdev/20241210002626.366878-1-ahmed.zaki@intel.com/
    - move static inline affinity functions to net/dev/core.c
    - add the new napi->irq_flags (patch 1)
    - add code changes to bnxt, mlx4 and ice.

Ahmed Zaki (6):
  net: move ARFS rmap management to core
  net: napi: add internal ARFS rmap management
  net: napi: add CPU affinity to napi_config
  bnxt: use napi's irq affinity
  ice: use napi's irq affinity
  idpf: use napi's irq affinity

 drivers/net/ethernet/amazon/ena/ena_netdev.c |  38 +----
 drivers/net/ethernet/broadcom/bnxt/bnxt.c    |  52 +------
 drivers/net/ethernet/broadcom/bnxt/bnxt.h    |   2 -
 drivers/net/ethernet/intel/ice/ice.h         |   3 -
 drivers/net/ethernet/intel/ice/ice_arfs.c    |  17 +--
 drivers/net/ethernet/intel/ice/ice_base.c    |   7 +-
 drivers/net/ethernet/intel/ice/ice_lib.c     |   6 -
 drivers/net/ethernet/intel/ice/ice_main.c    |  47 +-----
 drivers/net/ethernet/intel/idpf/idpf_lib.c   |   1 +
 drivers/net/ethernet/intel/idpf/idpf_txrx.c  |  22 +--
 drivers/net/ethernet/intel/idpf/idpf_txrx.h  |   6 +-
 include/linux/cpu_rmap.h                     |   1 +
 include/linux/netdevice.h                    |  31 +++-
 lib/cpu_rmap.c                               |   2 +-
 net/core/dev.c                               | 151 ++++++++++++++++++-
 15 files changed, 205 insertions(+), 181 deletions(-)

-- 
2.43.0

[PATCH net-next v5 1/6] net: move ARFS rmap management to core

[Ahmed Zaki]

Add a new netdev flag "rx_cpu_rmap_auto". Drivers supporting ARFS should
set the flag via netif_enable_cpu_rmap() and core will allocate and manage
the ARFS rmap. Freeing the rmap is also done by core when the netdev is
freed.

Signed-off-by: Ahmed Zaki <ahmed.zaki@intel.com>
---
 drivers/net/ethernet/amazon/ena/ena_netdev.c | 38 ++---------------
 drivers/net/ethernet/broadcom/bnxt/bnxt.c    | 27 ++----------
 drivers/net/ethernet/intel/ice/ice_arfs.c    | 17 +-------
 include/linux/netdevice.h                    | 15 +++++--
 net/core/dev.c                               | 44 ++++++++++++++++++++
 5 files changed, 63 insertions(+), 78 deletions(-)

diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.c b/drivers/net/ethernet/amazon/ena/ena_netdev.c
index c1295dfad0d0..a3fceaa83cd5 100644
--- a/drivers/net/ethernet/amazon/ena/ena_netdev.c
+++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c
@@ -5,9 +5,6 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
-#ifdef CONFIG_RFS_ACCEL
-#include <linux/cpu_rmap.h>
-#endif /* CONFIG_RFS_ACCEL */
 #include <linux/ethtool.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
@@ -165,25 +162,10 @@ int ena_xmit_common(struct ena_adapter *adapter,
 static int ena_init_rx_cpu_rmap(struct ena_adapter *adapter)
 {
 #ifdef CONFIG_RFS_ACCEL
-	u32 i;
-	int rc;
-
-	adapter->netdev->rx_cpu_rmap = alloc_irq_cpu_rmap(adapter->num_io_queues);
-	if (!adapter->netdev->rx_cpu_rmap)
-		return -ENOMEM;
-	for (i = 0; i < adapter->num_io_queues; i++) {
-		int irq_idx = ENA_IO_IRQ_IDX(i);
-
-		rc = irq_cpu_rmap_add(adapter->netdev->rx_cpu_rmap,
-				      pci_irq_vector(adapter->pdev, irq_idx));
-		if (rc) {
-			free_irq_cpu_rmap(adapter->netdev->rx_cpu_rmap);
-			adapter->netdev->rx_cpu_rmap = NULL;
-			return rc;
-		}
-	}
-#endif /* CONFIG_RFS_ACCEL */
+	return netif_enable_cpu_rmap(adapter->netdev, adapter->num_io_queues);
+#else
 	return 0;
+#endif /* CONFIG_RFS_ACCEL */
 }
 
 static void ena_init_io_rings_common(struct ena_adapter *adapter,
@@ -1742,13 +1724,6 @@ static void ena_free_io_irq(struct ena_adapter *adapter)
 	struct ena_irq *irq;
 	int i;
 
-#ifdef CONFIG_RFS_ACCEL
-	if (adapter->msix_vecs >= 1) {
-		free_irq_cpu_rmap(adapter->netdev->rx_cpu_rmap);
-		adapter->netdev->rx_cpu_rmap = NULL;
-	}
-#endif /* CONFIG_RFS_ACCEL */
-
 	for (i = ENA_IO_IRQ_FIRST_IDX; i < ENA_MAX_MSIX_VEC(io_queue_count); i++) {
 		irq = &adapter->irq_tbl[i];
 		irq_set_affinity_hint(irq->vector, NULL);
@@ -4131,13 +4106,6 @@ static void __ena_shutoff(struct pci_dev *pdev, bool shutdown)
 	ena_dev = adapter->ena_dev;
 	netdev = adapter->netdev;
 
-#ifdef CONFIG_RFS_ACCEL
-	if ((adapter->msix_vecs >= 1) && (netdev->rx_cpu_rmap)) {
-		free_irq_cpu_rmap(netdev->rx_cpu_rmap);
-		netdev->rx_cpu_rmap = NULL;
-	}
-
-#endif /* CONFIG_RFS_ACCEL */
 	/* Make sure timer and reset routine won't be called after
 	 * freeing device resources.
 	 */
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 884d42db5554..1f50bc715038 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -49,7 +49,6 @@
 #include <linux/cache.h>
 #include <linux/log2.h>
 #include <linux/bitmap.h>
-#include <linux/cpu_rmap.h>
 #include <linux/cpumask.h>
 #include <net/pkt_cls.h>
 #include <net/page_pool/helpers.h>
@@ -10861,7 +10860,7 @@ static int bnxt_set_real_num_queues(struct bnxt *bp)
 
 #ifdef CONFIG_RFS_ACCEL
 	if (bp->flags & BNXT_FLAG_RFS)
-		dev->rx_cpu_rmap = alloc_irq_cpu_rmap(bp->rx_nr_rings);
+		return netif_enable_cpu_rmap(dev, bp->rx_nr_rings);
 #endif
 
 	return rc;
@@ -11215,10 +11214,6 @@ static void bnxt_free_irq(struct bnxt *bp)
 	struct bnxt_irq *irq;
 	int i;
 
-#ifdef CONFIG_RFS_ACCEL
-	free_irq_cpu_rmap(bp->dev->rx_cpu_rmap);
-	bp->dev->rx_cpu_rmap = NULL;
-#endif
 	if (!bp->irq_tbl || !bp->bnapi)
 		return;
 
@@ -11241,11 +11236,8 @@ static void bnxt_free_irq(struct bnxt *bp)
 
 static int bnxt_request_irq(struct bnxt *bp)
 {
-	int i, j, rc = 0;
+	int i, rc = 0;
 	unsigned long flags = 0;
-#ifdef CONFIG_RFS_ACCEL
-	struct cpu_rmap *rmap;
-#endif
 
 	rc = bnxt_setup_int_mode(bp);
 	if (rc) {
@@ -11253,22 +11245,11 @@ static int bnxt_request_irq(struct bnxt *bp)
 			   rc);
 		return rc;
 	}
-#ifdef CONFIG_RFS_ACCEL
-	rmap = bp->dev->rx_cpu_rmap;
-#endif
-	for (i = 0, j = 0; i < bp->cp_nr_rings; i++) {
+
+	for (i = 0; i < bp->cp_nr_rings; i++) {
 		int map_idx = bnxt_cp_num_to_irq_num(bp, i);
 		struct bnxt_irq *irq = &bp->irq_tbl[map_idx];
 
-#ifdef CONFIG_RFS_ACCEL
-		if (rmap && bp->bnapi[i]->rx_ring) {
-			rc = irq_cpu_rmap_add(rmap, irq->vector);
-			if (rc)
-				netdev_warn(bp->dev, "failed adding irq rmap for ring %d\n",
-					    j);
-			j++;
-		}
-#endif
 		rc = request_irq(irq->vector, irq->handler, flags, irq->name,
 				 bp->bnapi[i]);
 		if (rc)
diff --git a/drivers/net/ethernet/intel/ice/ice_arfs.c b/drivers/net/ethernet/intel/ice/ice_arfs.c
index 7cee365cc7d1..3b1b892e6958 100644
--- a/drivers/net/ethernet/intel/ice/ice_arfs.c
+++ b/drivers/net/ethernet/intel/ice/ice_arfs.c
@@ -584,9 +584,6 @@ void ice_free_cpu_rx_rmap(struct ice_vsi *vsi)
 	netdev = vsi->netdev;
 	if (!netdev || !netdev->rx_cpu_rmap)
 		return;
-
-	free_irq_cpu_rmap(netdev->rx_cpu_rmap);
-	netdev->rx_cpu_rmap = NULL;
 }
 
 /**
@@ -597,7 +594,6 @@ int ice_set_cpu_rx_rmap(struct ice_vsi *vsi)
 {
 	struct net_device *netdev;
 	struct ice_pf *pf;
-	int i;
 
 	if (!vsi || vsi->type != ICE_VSI_PF)
 		return 0;
@@ -610,18 +606,7 @@ int ice_set_cpu_rx_rmap(struct ice_vsi *vsi)
 	netdev_dbg(netdev, "Setup CPU RMAP: vsi type 0x%x, ifname %s, q_vectors %d\n",
 		   vsi->type, netdev->name, vsi->num_q_vectors);
 
-	netdev->rx_cpu_rmap = alloc_irq_cpu_rmap(vsi->num_q_vectors);
-	if (unlikely(!netdev->rx_cpu_rmap))
-		return -EINVAL;
-
-	ice_for_each_q_vector(vsi, i)
-		if (irq_cpu_rmap_add(netdev->rx_cpu_rmap,
-				     vsi->q_vectors[i]->irq.virq)) {
-			ice_free_cpu_rx_rmap(vsi);
-			return -EINVAL;
-		}
-
-	return 0;
+	return netif_enable_cpu_rmap(netdev, vsi->num_q_vectors);
 }
 
 /**
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index aeb4a6cff171..7e95e9ee36dd 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1991,6 +1991,9 @@ enum netdev_reg_state {
  *
  *	@threaded:	napi threaded mode is enabled
  *
+ *	@rx_cpu_rmap_auto: driver wants the core to manage the ARFS rmap.
+ *	                   Set by calling netif_enable_cpu_rmap().
+ *
  *	@see_all_hwtstamp_requests: device wants to see calls to
  *			ndo_hwtstamp_set() for all timestamp requests
  *			regardless of source, even if those aren't
@@ -2398,6 +2401,9 @@ struct net_device {
 	struct lock_class_key	*qdisc_tx_busylock;
 	bool			proto_down;
 	bool			threaded;
+#ifdef CONFIG_RFS_ACCEL
+	bool			rx_cpu_rmap_auto;
+#endif
 
 	/* priv_flags_slow, ungrouped to save space */
 	unsigned long		see_all_hwtstamp_requests:1;
@@ -2671,10 +2677,7 @@ void netif_queue_set_napi(struct net_device *dev, unsigned int queue_index,
 			  enum netdev_queue_type type,
 			  struct napi_struct *napi);
 
-static inline void netif_napi_set_irq(struct napi_struct *napi, int irq)
-{
-	napi->irq = irq;
-}
+void netif_napi_set_irq(struct napi_struct *napi, int irq);
 
 /* Default NAPI poll() weight
  * Device drivers are strongly advised to not use bigger value
@@ -2765,6 +2768,10 @@ static inline void netif_napi_del(struct napi_struct *napi)
 	synchronize_net();
 }
 
+#ifdef CONFIG_RFS_ACCEL
+int netif_enable_cpu_rmap(struct net_device *dev, unsigned int num_irqs);
+
+#endif
 struct packet_type {
 	__be16			type;	/* This is really htons(ether_type). */
 	bool			ignore_outgoing;
diff --git a/net/core/dev.c b/net/core/dev.c
index 1a90ed8cc6cc..3ee7a514dca8 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6745,6 +6745,46 @@ void netif_queue_set_napi(struct net_device *dev, unsigned int queue_index,
 }
 EXPORT_SYMBOL(netif_queue_set_napi);
 
+#ifdef CONFIG_RFS_ACCEL
+static void netif_disable_cpu_rmap(struct net_device *dev)
+{
+	free_irq_cpu_rmap(dev->rx_cpu_rmap);
+	dev->rx_cpu_rmap = NULL;
+	dev->rx_cpu_rmap_auto = false;
+}
+
+int netif_enable_cpu_rmap(struct net_device *dev, unsigned int num_irqs)
+{
+	dev->rx_cpu_rmap = alloc_irq_cpu_rmap(num_irqs);
+	if (!dev->rx_cpu_rmap)
+		return -ENOMEM;
+
+	dev->rx_cpu_rmap_auto = true;
+	return 0;
+}
+EXPORT_SYMBOL(netif_enable_cpu_rmap);
+#endif
+
+void netif_napi_set_irq(struct napi_struct *napi, int irq)
+{
+#ifdef CONFIG_RFS_ACCEL
+	int rc;
+#endif
+	napi->irq = irq;
+
+#ifdef CONFIG_RFS_ACCEL
+	if (napi->dev->rx_cpu_rmap && napi->dev->rx_cpu_rmap_auto) {
+		rc = irq_cpu_rmap_add(napi->dev->rx_cpu_rmap, irq);
+		if (rc) {
+			netdev_warn(napi->dev, "Unable to update ARFS map (%d)\n",
+				    rc);
+			netif_disable_cpu_rmap(napi->dev);
+		}
+	}
+#endif
+}
+EXPORT_SYMBOL(netif_napi_set_irq);
+
 static void napi_restore_config(struct napi_struct *n)
 {
 	n->defer_hard_irqs = n->config->defer_hard_irqs;
@@ -11421,6 +11461,10 @@ void free_netdev(struct net_device *dev)
 	/* Flush device addresses */
 	dev_addr_flush(dev);
 
+#ifdef CONFIG_RFS_ACCEL
+	if (dev->rx_cpu_rmap && dev->rx_cpu_rmap_auto)
+		netif_disable_cpu_rmap(dev);
+#endif
 	list_for_each_entry_safe(p, n, &dev->napi_list, dev_list)
 		netif_napi_del(p);
 
-- 
2.43.0

[PATCH net-next v5 2/6] net: napi: add internal ARFS rmap management

[Ahmed Zaki]

For drivers using the netif_enable_cpu_rmap(), move the IRQ rmap notifier
inside the napi_struct.

Signed-off-by: Ahmed Zaki <ahmed.zaki@intel.com>
---
 include/linux/cpu_rmap.h  |  1 +
 include/linux/netdevice.h |  4 ++
 lib/cpu_rmap.c            |  2 +-
 net/core/dev.c            | 77 ++++++++++++++++++++++++++++++++++++++-
 4 files changed, 81 insertions(+), 3 deletions(-)

diff --git a/include/linux/cpu_rmap.h b/include/linux/cpu_rmap.h
index 20b5729903d7..2fd7ba75362a 100644
--- a/include/linux/cpu_rmap.h
+++ b/include/linux/cpu_rmap.h
@@ -32,6 +32,7 @@ struct cpu_rmap {
 #define CPU_RMAP_DIST_INF 0xffff
 
 extern struct cpu_rmap *alloc_cpu_rmap(unsigned int size, gfp_t flags);
+extern void cpu_rmap_get(struct cpu_rmap *rmap);
 extern int cpu_rmap_put(struct cpu_rmap *rmap);
 
 extern int cpu_rmap_add(struct cpu_rmap *rmap, void *obj);
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 7e95e9ee36dd..6f8b416aa32b 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -392,6 +392,10 @@ struct napi_struct {
 	struct list_head	dev_list;
 	struct hlist_node	napi_hash_node;
 	int			irq;
+#ifdef CONFIG_RFS_ACCEL
+	struct irq_affinity_notify notify;
+	int			napi_rmap_idx;
+#endif
 	int			index;
 	struct napi_config	*config;
 };
diff --git a/lib/cpu_rmap.c b/lib/cpu_rmap.c
index 4c348670da31..f03d9be3f06b 100644
--- a/lib/cpu_rmap.c
+++ b/lib/cpu_rmap.c
@@ -73,7 +73,7 @@ static void cpu_rmap_release(struct kref *ref)
  * cpu_rmap_get - internal helper to get new ref on a cpu_rmap
  * @rmap: reverse-map allocated with alloc_cpu_rmap()
  */
-static inline void cpu_rmap_get(struct cpu_rmap *rmap)
+void cpu_rmap_get(struct cpu_rmap *rmap)
 {
 	kref_get(&rmap->refcount);
 }
diff --git a/net/core/dev.c b/net/core/dev.c
index 3ee7a514dca8..c965d947b33d 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6748,7 +6748,20 @@ EXPORT_SYMBOL(netif_queue_set_napi);
 #ifdef CONFIG_RFS_ACCEL
 static void netif_disable_cpu_rmap(struct net_device *dev)
 {
-	free_irq_cpu_rmap(dev->rx_cpu_rmap);
+	struct cpu_rmap *rmap = dev->rx_cpu_rmap;
+	struct napi_struct *napi;
+	u16 index;
+
+	if (!rmap || !dev->rx_cpu_rmap_auto)
+		return;
+
+	for (index = 0; index < rmap->size; index++) {
+		napi = rmap->obj[index];
+		if (napi && napi->irq > 0)
+			irq_set_affinity_notifier(napi->irq, NULL);
+	}
+
+	cpu_rmap_put(rmap);
 	dev->rx_cpu_rmap = NULL;
 	dev->rx_cpu_rmap_auto = false;
 }
@@ -6763,6 +6776,66 @@ int netif_enable_cpu_rmap(struct net_device *dev, unsigned int num_irqs)
 	return 0;
 }
 EXPORT_SYMBOL(netif_enable_cpu_rmap);
+
+static void
+netif_irq_cpu_rmap_notify(struct irq_affinity_notify *notify,
+			  const cpumask_t *mask)
+{
+	struct napi_struct *napi =
+		container_of(notify, struct napi_struct, notify);
+	struct cpu_rmap *rmap = napi->dev->rx_cpu_rmap;
+	int err;
+
+	if (rmap && napi->dev->rx_cpu_rmap_auto) {
+		err = cpu_rmap_update(rmap, napi->napi_rmap_idx, mask);
+		if (err)
+			pr_warn("%s: RMAP update failed (%d)\n",
+				__func__, err);
+	}
+}
+
+static void
+netif_napi_affinity_release(struct kref *ref)
+{
+	struct napi_struct *napi =
+		container_of(ref, struct napi_struct, notify.kref);
+	struct cpu_rmap *rmap = napi->dev->rx_cpu_rmap;
+
+	if (!rmap || !napi->dev->rx_cpu_rmap_auto)
+		return;
+
+	rmap->obj[napi->napi_rmap_idx] = NULL;
+	cpu_rmap_put(rmap);
+}
+
+static int napi_irq_cpu_rmap_add(struct napi_struct *napi, int irq)
+{
+	struct cpu_rmap *rmap = napi->dev->rx_cpu_rmap;
+	int rc;
+
+	if (!rmap)
+		return -EINVAL;
+
+	napi->notify.notify = netif_irq_cpu_rmap_notify;
+	napi->notify.release = netif_napi_affinity_release;
+	cpu_rmap_get(rmap);
+	rc = cpu_rmap_add(rmap, napi);
+	if (rc < 0)
+		goto err_add;
+
+	napi->napi_rmap_idx = rc;
+	rc = irq_set_affinity_notifier(irq, &napi->notify);
+	if (rc)
+		goto err_set;
+
+	return 0;
+
+err_set:
+	rmap->obj[napi->napi_rmap_idx] = NULL;
+err_add:
+	cpu_rmap_put(rmap);
+	return rc;
+}
 #endif
 
 void netif_napi_set_irq(struct napi_struct *napi, int irq)
@@ -6774,7 +6847,7 @@ void netif_napi_set_irq(struct napi_struct *napi, int irq)
 
 #ifdef CONFIG_RFS_ACCEL
 	if (napi->dev->rx_cpu_rmap && napi->dev->rx_cpu_rmap_auto) {
-		rc = irq_cpu_rmap_add(napi->dev->rx_cpu_rmap, irq);
+		rc = napi_irq_cpu_rmap_add(napi, irq);
 		if (rc) {
 			netdev_warn(napi->dev, "Unable to update ARFS map (%d)\n",
 				    rc);
-- 
2.43.0

[PATCH net-next v5 3/6] net: napi: add CPU affinity to napi_config

[Ahmed Zaki]

A common task for most drivers is to remember the user-set CPU affinity
to its IRQs. On each netdev reset, the driver should re-assign the
user's settings to the IRQs.

Add CPU affinity mask to napi_config. To delegate the CPU affinity
management to the core, drivers must:
 1 - set the new netdev flag "irq_affinity_auto":
                                       netif_enable_irq_affinity(netdev)
 2 - create the napi with persistent config:
                                       netif_napi_add_config()
 3 - bind an IRQ to the napi instance: netif_napi_set_irq()

the core will then make sure to use re-assign affinity to the napi's
IRQ.

The default IRQ mask is set to one cpu starting from the closest NUMA.

Signed-off-by: Ahmed Zaki <ahmed.zaki@intel.com>
---
 include/linux/netdevice.h | 14 +++++++++++-
 net/core/dev.c            | 46 +++++++++++++++++++++++++++++++++------
 2 files changed, 52 insertions(+), 8 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 6f8b416aa32b..8b31fff8affa 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -351,6 +351,7 @@ struct napi_config {
 	u64 gro_flush_timeout;
 	u64 irq_suspend_timeout;
 	u32 defer_hard_irqs;
+	cpumask_t affinity_mask;
 	unsigned int napi_id;
 };
 
@@ -392,8 +393,8 @@ struct napi_struct {
 	struct list_head	dev_list;
 	struct hlist_node	napi_hash_node;
 	int			irq;
-#ifdef CONFIG_RFS_ACCEL
 	struct irq_affinity_notify notify;
+#ifdef CONFIG_RFS_ACCEL
 	int			napi_rmap_idx;
 #endif
 	int			index;
@@ -1995,6 +1996,11 @@ enum netdev_reg_state {
  *
  *	@threaded:	napi threaded mode is enabled
  *
+ *	@irq_affinity_auto: driver wants the core to manage the IRQ affinity.
+ *			    Set by netif_napi_set_irq(), then driver must
+ *			    create persistent napi by netif_napi_add_config()
+ *			    and finally bind napi to IRQ (netif_napi_set_irq).
+ *
  *	@rx_cpu_rmap_auto: driver wants the core to manage the ARFS rmap.
  *	                   Set by calling netif_enable_cpu_rmap().
  *
@@ -2405,6 +2411,7 @@ struct net_device {
 	struct lock_class_key	*qdisc_tx_busylock;
 	bool			proto_down;
 	bool			threaded;
+	bool			irq_affinity_auto;
 #ifdef CONFIG_RFS_ACCEL
 	bool			rx_cpu_rmap_auto;
 #endif
@@ -2640,6 +2647,11 @@ static inline void netdev_set_ml_priv(struct net_device *dev,
 	dev->ml_priv_type = type;
 }
 
+static inline void netif_enable_irq_affinity(struct net_device *dev)
+{
+	dev->irq_affinity_auto = true;
+}
+
 /*
  * Net namespace inlines
  */
diff --git a/net/core/dev.c b/net/core/dev.c
index c965d947b33d..1fb850322868 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6776,27 +6776,36 @@ int netif_enable_cpu_rmap(struct net_device *dev, unsigned int num_irqs)
 	return 0;
 }
 EXPORT_SYMBOL(netif_enable_cpu_rmap);
+#endif
 
 static void
-netif_irq_cpu_rmap_notify(struct irq_affinity_notify *notify,
-			  const cpumask_t *mask)
+netif_napi_irq_notify(struct irq_affinity_notify *notify,
+		      const cpumask_t *mask)
 {
 	struct napi_struct *napi =
 		container_of(notify, struct napi_struct, notify);
+#ifdef CONFIG_RFS_ACCEL
 	struct cpu_rmap *rmap = napi->dev->rx_cpu_rmap;
 	int err;
+#endif
 
+	if (napi->config && napi->dev->irq_affinity_auto)
+		cpumask_copy(&napi->config->affinity_mask, mask);
+
+#ifdef CONFIG_RFS_ACCEL
 	if (rmap && napi->dev->rx_cpu_rmap_auto) {
 		err = cpu_rmap_update(rmap, napi->napi_rmap_idx, mask);
 		if (err)
 			pr_warn("%s: RMAP update failed (%d)\n",
 				__func__, err);
 	}
+#endif
 }
 
 static void
 netif_napi_affinity_release(struct kref *ref)
 {
+#ifdef CONFIG_RFS_ACCEL
 	struct napi_struct *napi =
 		container_of(ref, struct napi_struct, notify.kref);
 	struct cpu_rmap *rmap = napi->dev->rx_cpu_rmap;
@@ -6806,8 +6815,10 @@ netif_napi_affinity_release(struct kref *ref)
 
 	rmap->obj[napi->napi_rmap_idx] = NULL;
 	cpu_rmap_put(rmap);
+#endif
 }
 
+#ifdef CONFIG_RFS_ACCEL
 static int napi_irq_cpu_rmap_add(struct napi_struct *napi, int irq)
 {
 	struct cpu_rmap *rmap = napi->dev->rx_cpu_rmap;
@@ -6816,7 +6827,7 @@ static int napi_irq_cpu_rmap_add(struct napi_struct *napi, int irq)
 	if (!rmap)
 		return -EINVAL;
 
-	napi->notify.notify = netif_irq_cpu_rmap_notify;
+	napi->notify.notify = netif_napi_irq_notify;
 	napi->notify.release = netif_napi_affinity_release;
 	cpu_rmap_get(rmap);
 	rc = cpu_rmap_add(rmap, napi);
@@ -6840,9 +6851,8 @@ static int napi_irq_cpu_rmap_add(struct napi_struct *napi, int irq)
 
 void netif_napi_set_irq(struct napi_struct *napi, int irq)
 {
-#ifdef CONFIG_RFS_ACCEL
 	int rc;
-#endif
+
 	napi->irq = irq;
 
 #ifdef CONFIG_RFS_ACCEL
@@ -6853,8 +6863,18 @@ void netif_napi_set_irq(struct napi_struct *napi, int irq)
 				    rc);
 			netif_disable_cpu_rmap(napi->dev);
 		}
-	}
+	} else if (irq > 0 && napi->config && napi->dev->irq_affinity_auto) {
+#else
+	if (irq > 0 && napi->config && napi->dev->irq_affinity_auto) {
 #endif
+		napi->notify.notify = netif_napi_irq_notify;
+		napi->notify.release = netif_napi_affinity_release;
+
+		rc = irq_set_affinity_notifier(irq, &napi->notify);
+		if (rc)
+			netdev_warn(napi->dev, "Unable to set IRQ notifier (%d)\n",
+				    rc);
+	}
 }
 EXPORT_SYMBOL(netif_napi_set_irq);
 
@@ -6863,6 +6883,10 @@ static void napi_restore_config(struct napi_struct *n)
 	n->defer_hard_irqs = n->config->defer_hard_irqs;
 	n->gro_flush_timeout = n->config->gro_flush_timeout;
 	n->irq_suspend_timeout = n->config->irq_suspend_timeout;
+
+	if (n->irq > 0 && n->dev->irq_affinity_auto)
+		irq_set_affinity(n->irq, &n->config->affinity_mask);
+
 	/* a NAPI ID might be stored in the config, if so use it. if not, use
 	 * napi_hash_add to generate one for us.
 	 */
@@ -6879,6 +6903,10 @@ static void napi_save_config(struct napi_struct *n)
 	n->config->defer_hard_irqs = n->defer_hard_irqs;
 	n->config->gro_flush_timeout = n->gro_flush_timeout;
 	n->config->irq_suspend_timeout = n->irq_suspend_timeout;
+
+	if (n->irq > 0 && n->dev->irq_affinity_auto)
+		irq_set_affinity_notifier(n->irq, NULL);
+
 	napi_hash_del(n);
 }
 
@@ -11377,7 +11405,7 @@ struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
 {
 	struct net_device *dev;
 	size_t napi_config_sz;
-	unsigned int maxqs;
+	unsigned int maxqs, i, numa;
 
 	BUG_ON(strlen(name) >= sizeof(dev->name));
 
@@ -11473,6 +11501,10 @@ struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
 	dev->napi_config = kvzalloc(napi_config_sz, GFP_KERNEL_ACCOUNT);
 	if (!dev->napi_config)
 		goto free_all;
+	numa = dev_to_node(&dev->dev);
+	for (i = 0; i < maxqs; i++)
+		cpumask_set_cpu(cpumask_local_spread(i, numa),
+				&dev->napi_config[i].affinity_mask);
 
 	strscpy(dev->name, name);
 	dev->name_assign_type = name_assign_type;
-- 
2.43.0

[PATCH net-next v5 4/6] bnxt: use napi's irq affinity

[Ahmed Zaki]

Delete the driver CPU affinity info and use the core's napi config
instead.

Signed-off-by: Ahmed Zaki <ahmed.zaki@intel.com>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt.c | 25 +++--------------------
 drivers/net/ethernet/broadcom/bnxt/bnxt.h |  2 --
 2 files changed, 3 insertions(+), 24 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 1f50bc715038..7b8b42adc76d 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -11221,14 +11221,8 @@ static void bnxt_free_irq(struct bnxt *bp)
 		int map_idx = bnxt_cp_num_to_irq_num(bp, i);
 
 		irq = &bp->irq_tbl[map_idx];
-		if (irq->requested) {
-			if (irq->have_cpumask) {
-				irq_update_affinity_hint(irq->vector, NULL);
-				free_cpumask_var(irq->cpu_mask);
-				irq->have_cpumask = 0;
-			}
+		if (irq->requested)
 			free_irq(irq->vector, bp->bnapi[i]);
-		}
 
 		irq->requested = 0;
 	}
@@ -11257,21 +11251,6 @@ static int bnxt_request_irq(struct bnxt *bp)
 
 		netif_napi_set_irq(&bp->bnapi[i]->napi, irq->vector);
 		irq->requested = 1;
-
-		if (zalloc_cpumask_var(&irq->cpu_mask, GFP_KERNEL)) {
-			int numa_node = dev_to_node(&bp->pdev->dev);
-
-			irq->have_cpumask = 1;
-			cpumask_set_cpu(cpumask_local_spread(i, numa_node),
-					irq->cpu_mask);
-			rc = irq_update_affinity_hint(irq->vector, irq->cpu_mask);
-			if (rc) {
-				netdev_warn(bp->dev,
-					    "Update affinity hint failed, IRQ = %d\n",
-					    irq->vector);
-				break;
-			}
-		}
 	}
 	return rc;
 }
@@ -16200,6 +16179,8 @@ static int bnxt_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 	dev->xdp_features = NETDEV_XDP_ACT_BASIC | NETDEV_XDP_ACT_REDIRECT |
 			    NETDEV_XDP_ACT_RX_SG;
 
+	netif_enable_irq_affinity(dev);
+
 #ifdef CONFIG_BNXT_SRIOV
 	init_waitqueue_head(&bp->sriov_cfg_wait);
 #endif
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.h b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
index 094c9e95b463..7be2f90d0c05 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.h
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
@@ -1228,9 +1228,7 @@ struct bnxt_irq {
 	irq_handler_t	handler;
 	unsigned int	vector;
 	u8		requested:1;
-	u8		have_cpumask:1;
 	char		name[IFNAMSIZ + BNXT_IRQ_NAME_EXTRA];
-	cpumask_var_t	cpu_mask;
 };
 
 #define HWRM_RING_ALLOC_TX	0x1
-- 
2.43.0

[PATCH net-next v5 5/6] ice: use napi's irq affinity

[Ahmed Zaki]

Delete the driver CPU affinity info and use the core's napi config
instead.

Signed-off-by: Ahmed Zaki <ahmed.zaki@intel.com>
---
 drivers/net/ethernet/intel/ice/ice.h      |  3 --
 drivers/net/ethernet/intel/ice/ice_base.c |  7 +---
 drivers/net/ethernet/intel/ice/ice_lib.c  |  6 ---
 drivers/net/ethernet/intel/ice/ice_main.c | 47 ++---------------------
 4 files changed, 5 insertions(+), 58 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice.h b/drivers/net/ethernet/intel/ice/ice.h
index 71e05d30f0fd..a6e6c9e1edc1 100644
--- a/drivers/net/ethernet/intel/ice/ice.h
+++ b/drivers/net/ethernet/intel/ice/ice.h
@@ -478,9 +478,6 @@ struct ice_q_vector {
 	struct ice_ring_container rx;
 	struct ice_ring_container tx;
 
-	cpumask_t affinity_mask;
-	struct irq_affinity_notify affinity_notify;
-
 	struct ice_channel *ch;
 
 	char name[ICE_INT_NAME_STR_LEN];
diff --git a/drivers/net/ethernet/intel/ice/ice_base.c b/drivers/net/ethernet/intel/ice/ice_base.c
index b2af8e3586f7..86cf715de00f 100644
--- a/drivers/net/ethernet/intel/ice/ice_base.c
+++ b/drivers/net/ethernet/intel/ice/ice_base.c
@@ -147,10 +147,6 @@ static int ice_vsi_alloc_q_vector(struct ice_vsi *vsi, u16 v_idx)
 	q_vector->reg_idx = q_vector->irq.index;
 	q_vector->vf_reg_idx = q_vector->irq.index;
 
-	/* only set affinity_mask if the CPU is online */
-	if (cpu_online(v_idx))
-		cpumask_set_cpu(v_idx, &q_vector->affinity_mask);
-
 	/* This will not be called in the driver load path because the netdev
 	 * will not be created yet. All other cases with register the NAPI
 	 * handler here (i.e. resume, reset/rebuild, etc.)
@@ -276,7 +272,8 @@ static void ice_cfg_xps_tx_ring(struct ice_tx_ring *ring)
 	if (test_and_set_bit(ICE_TX_XPS_INIT_DONE, ring->xps_state))
 		return;
 
-	netif_set_xps_queue(ring->netdev, &ring->q_vector->affinity_mask,
+	netif_set_xps_queue(ring->netdev,
+			    &ring->q_vector->napi.config->affinity_mask,
 			    ring->q_index);
 }
 
diff --git a/drivers/net/ethernet/intel/ice/ice_lib.c b/drivers/net/ethernet/intel/ice/ice_lib.c
index a7d45a8ce7ac..b5b93a426933 100644
--- a/drivers/net/ethernet/intel/ice/ice_lib.c
+++ b/drivers/net/ethernet/intel/ice/ice_lib.c
@@ -2589,12 +2589,6 @@ void ice_vsi_free_irq(struct ice_vsi *vsi)
 		      vsi->q_vectors[i]->num_ring_rx))
 			continue;
 
-		/* clear the affinity notifier in the IRQ descriptor */
-		if (!IS_ENABLED(CONFIG_RFS_ACCEL))
-			irq_set_affinity_notifier(irq_num, NULL);
-
-		/* clear the affinity_hint in the IRQ descriptor */
-		irq_update_affinity_hint(irq_num, NULL);
 		synchronize_irq(irq_num);
 		devm_free_irq(ice_pf_to_dev(pf), irq_num, vsi->q_vectors[i]);
 	}
diff --git a/drivers/net/ethernet/intel/ice/ice_main.c b/drivers/net/ethernet/intel/ice/ice_main.c
index 1701f7143f24..8df7332fcbbb 100644
--- a/drivers/net/ethernet/intel/ice/ice_main.c
+++ b/drivers/net/ethernet/intel/ice/ice_main.c
@@ -2512,34 +2512,6 @@ int ice_schedule_reset(struct ice_pf *pf, enum ice_reset_req reset)
 	return 0;
 }
 
-/**
- * ice_irq_affinity_notify - Callback for affinity changes
- * @notify: context as to what irq was changed
- * @mask: the new affinity mask
- *
- * This is a callback function used by the irq_set_affinity_notifier function
- * so that we may register to receive changes to the irq affinity masks.
- */
-static void
-ice_irq_affinity_notify(struct irq_affinity_notify *notify,
-			const cpumask_t *mask)
-{
-	struct ice_q_vector *q_vector =
-		container_of(notify, struct ice_q_vector, affinity_notify);
-
-	cpumask_copy(&q_vector->affinity_mask, mask);
-}
-
-/**
- * ice_irq_affinity_release - Callback for affinity notifier release
- * @ref: internal core kernel usage
- *
- * This is a callback function used by the irq_set_affinity_notifier function
- * to inform the current notification subscriber that they will no longer
- * receive notifications.
- */
-static void ice_irq_affinity_release(struct kref __always_unused *ref) {}
-
 /**
  * ice_vsi_ena_irq - Enable IRQ for the given VSI
  * @vsi: the VSI being configured
@@ -2603,19 +2575,6 @@ static int ice_vsi_req_irq_msix(struct ice_vsi *vsi, char *basename)
 				   err);
 			goto free_q_irqs;
 		}
-
-		/* register for affinity change notifications */
-		if (!IS_ENABLED(CONFIG_RFS_ACCEL)) {
-			struct irq_affinity_notify *affinity_notify;
-
-			affinity_notify = &q_vector->affinity_notify;
-			affinity_notify->notify = ice_irq_affinity_notify;
-			affinity_notify->release = ice_irq_affinity_release;
-			irq_set_affinity_notifier(irq_num, affinity_notify);
-		}
-
-		/* assign the mask for this irq */
-		irq_update_affinity_hint(irq_num, &q_vector->affinity_mask);
 	}
 
 	err = ice_set_cpu_rx_rmap(vsi);
@@ -2631,9 +2590,6 @@ static int ice_vsi_req_irq_msix(struct ice_vsi *vsi, char *basename)
 free_q_irqs:
 	while (vector--) {
 		irq_num = vsi->q_vectors[vector]->irq.virq;
-		if (!IS_ENABLED(CONFIG_RFS_ACCEL))
-			irq_set_affinity_notifier(irq_num, NULL);
-		irq_update_affinity_hint(irq_num, NULL);
 		devm_free_irq(dev, irq_num, &vsi->q_vectors[vector]);
 	}
 	return err;
@@ -3674,6 +3630,9 @@ void ice_set_netdev_features(struct net_device *netdev)
 	 */
 	netdev->hw_features |= NETIF_F_RXFCS;
 
+	/* Allow core to manage IRQs affinity */
+	netif_enable_irq_affinity(netdev);
+
 	netif_set_tso_max_size(netdev, ICE_MAX_TSO_SIZE);
 }
 
-- 
2.43.0

[PATCH net-next v5 6/6] idpf: use napi's irq affinity

[Ahmed Zaki]

Delete the driver CPU affinity info and use the core's napi config
instead.

Signed-off-by: Ahmed Zaki <ahmed.zaki@intel.com>
---
 drivers/net/ethernet/intel/idpf/idpf_lib.c  |  1 +
 drivers/net/ethernet/intel/idpf/idpf_txrx.c | 22 +++++++--------------
 drivers/net/ethernet/intel/idpf/idpf_txrx.h |  6 ++----
 3 files changed, 10 insertions(+), 19 deletions(-)

diff --git a/drivers/net/ethernet/intel/idpf/idpf_lib.c b/drivers/net/ethernet/intel/idpf/idpf_lib.c
index b4fbb99bfad2..d54be068f53f 100644
--- a/drivers/net/ethernet/intel/idpf/idpf_lib.c
+++ b/drivers/net/ethernet/intel/idpf/idpf_lib.c
@@ -814,6 +814,7 @@ static int idpf_cfg_netdev(struct idpf_vport *vport)
 	netdev->hw_features |= dflt_features | offloads;
 	netdev->hw_enc_features |= dflt_features | offloads;
 	idpf_set_ethtool_ops(netdev);
+	netif_enable_irq_affinity(netdev);
 	SET_NETDEV_DEV(netdev, &adapter->pdev->dev);
 
 	/* carrier off on init to avoid Tx hangs */
diff --git a/drivers/net/ethernet/intel/idpf/idpf_txrx.c b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
index 2fa9c36e33c9..f6b5b45a061c 100644
--- a/drivers/net/ethernet/intel/idpf/idpf_txrx.c
+++ b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
@@ -3554,8 +3554,6 @@ void idpf_vport_intr_rel(struct idpf_vport *vport)
 		q_vector->tx = NULL;
 		kfree(q_vector->rx);
 		q_vector->rx = NULL;
-
-		free_cpumask_var(q_vector->affinity_mask);
 	}
 
 	kfree(vport->q_vectors);
@@ -3582,8 +3580,6 @@ static void idpf_vport_intr_rel_irq(struct idpf_vport *vport)
 		vidx = vport->q_vector_idxs[vector];
 		irq_num = adapter->msix_entries[vidx].vector;
 
-		/* clear the affinity_mask in the IRQ descriptor */
-		irq_set_affinity_hint(irq_num, NULL);
 		kfree(free_irq(irq_num, q_vector));
 	}
 }
@@ -3771,8 +3767,6 @@ static int idpf_vport_intr_req_irq(struct idpf_vport *vport)
 				   "Request_irq failed, error: %d\n", err);
 			goto free_q_irqs;
 		}
-		/* assign the mask for this irq */
-		irq_set_affinity_hint(irq_num, q_vector->affinity_mask);
 	}
 
 	return 0;
@@ -4184,7 +4178,8 @@ static int idpf_vport_intr_init_vec_idx(struct idpf_vport *vport)
 static void idpf_vport_intr_napi_add_all(struct idpf_vport *vport)
 {
 	int (*napi_poll)(struct napi_struct *napi, int budget);
-	u16 v_idx;
+	u16 v_idx, qv_idx;
+	int irq_num;
 
 	if (idpf_is_queue_model_split(vport->txq_model))
 		napi_poll = idpf_vport_splitq_napi_poll;
@@ -4193,12 +4188,12 @@ static void idpf_vport_intr_napi_add_all(struct idpf_vport *vport)
 
 	for (v_idx = 0; v_idx < vport->num_q_vectors; v_idx++) {
 		struct idpf_q_vector *q_vector = &vport->q_vectors[v_idx];
+		qv_idx = vport->q_vector_idxs[v_idx];
+		irq_num = vport->adapter->msix_entries[qv_idx].vector;
 
-		netif_napi_add(vport->netdev, &q_vector->napi, napi_poll);
-
-		/* only set affinity_mask if the CPU is online */
-		if (cpu_online(v_idx))
-			cpumask_set_cpu(v_idx, q_vector->affinity_mask);
+		netif_napi_add_config(vport->netdev, &q_vector->napi,
+				      napi_poll, v_idx);
+		netif_napi_set_irq(&q_vector->napi, irq_num);
 	}
 }
 
@@ -4242,9 +4237,6 @@ int idpf_vport_intr_alloc(struct idpf_vport *vport)
 		q_vector->rx_intr_mode = IDPF_ITR_DYNAMIC;
 		q_vector->rx_itr_idx = VIRTCHNL2_ITR_IDX_0;
 
-		if (!zalloc_cpumask_var(&q_vector->affinity_mask, GFP_KERNEL))
-			goto error;
-
 		q_vector->tx = kcalloc(txqs_per_vector, sizeof(*q_vector->tx),
 				       GFP_KERNEL);
 		if (!q_vector->tx)
diff --git a/drivers/net/ethernet/intel/idpf/idpf_txrx.h b/drivers/net/ethernet/intel/idpf/idpf_txrx.h
index 0f71a6f5557b..13251f63c7c3 100644
--- a/drivers/net/ethernet/intel/idpf/idpf_txrx.h
+++ b/drivers/net/ethernet/intel/idpf/idpf_txrx.h
@@ -401,7 +401,6 @@ struct idpf_intr_reg {
  * @rx_intr_mode: Dynamic ITR or not
  * @rx_itr_idx: RX ITR index
  * @v_idx: Vector index
- * @affinity_mask: CPU affinity mask
  */
 struct idpf_q_vector {
 	__cacheline_group_begin_aligned(read_mostly);
@@ -438,13 +437,12 @@ struct idpf_q_vector {
 	__cacheline_group_begin_aligned(cold);
 	u16 v_idx;
 
-	cpumask_var_t affinity_mask;
 	__cacheline_group_end_aligned(cold);
 };
 libeth_cacheline_set_assert(struct idpf_q_vector, 120,
 			    24 + sizeof(struct napi_struct) +
 			    2 * sizeof(struct dim),
-			    8 + sizeof(cpumask_var_t));
+			    8);
 
 struct idpf_rx_queue_stats {
 	u64_stats_t packets;
@@ -940,7 +938,7 @@ static inline int idpf_q_vector_to_mem(const struct idpf_q_vector *q_vector)
 	if (!q_vector)
 		return NUMA_NO_NODE;
 
-	cpu = cpumask_first(q_vector->affinity_mask);
+	cpu = cpumask_first(&q_vector->napi.config->affinity_mask);
 
 	return cpu < nr_cpu_ids ? cpu_to_mem(cpu) : NUMA_NO_NODE;
 }
-- 
2.43.0

RE: [PATCH net-next v5 1/6] net: move ARFS rmap management to core

[Arinzon, David]

> Add a new netdev flag "rx_cpu_rmap_auto". Drivers supporting ARFS should
> set the flag via netif_enable_cpu_rmap() and core will allocate and manage
> the ARFS rmap. Freeing the rmap is also done by core when the netdev is
> freed.
> 
> Signed-off-by: Ahmed Zaki <ahmed.zaki@intel.com>
> ---
>  drivers/net/ethernet/amazon/ena/ena_netdev.c | 38 ++---------------
>  drivers/net/ethernet/broadcom/bnxt/bnxt.c    | 27 ++----------
>  drivers/net/ethernet/intel/ice/ice_arfs.c    | 17 +-------
>  include/linux/netdevice.h                    | 15 +++++--
>  net/core/dev.c                               | 44 ++++++++++++++++++++
>  5 files changed, 63 insertions(+), 78 deletions(-)
> 
> diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.c
> b/drivers/net/ethernet/amazon/ena/ena_netdev.c
> index c1295dfad0d0..a3fceaa83cd5 100644
> --- a/drivers/net/ethernet/amazon/ena/ena_netdev.c
> +++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c
> @@ -5,9 +5,6 @@
> 
>  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> 
> -#ifdef CONFIG_RFS_ACCEL
> -#include <linux/cpu_rmap.h>
> -#endif /* CONFIG_RFS_ACCEL */
>  #include <linux/ethtool.h>
>  #include <linux/kernel.h>
>  #include <linux/module.h>
> @@ -165,25 +162,10 @@ int ena_xmit_common(struct ena_adapter
> *adapter,  static int ena_init_rx_cpu_rmap(struct ena_adapter *adapter)  {
> #ifdef CONFIG_RFS_ACCEL
> -       u32 i;
> -       int rc;
> -
> -       adapter->netdev->rx_cpu_rmap = alloc_irq_cpu_rmap(adapter-
> >num_io_queues);
> -       if (!adapter->netdev->rx_cpu_rmap)
> -               return -ENOMEM;
> -       for (i = 0; i < adapter->num_io_queues; i++) {
> -               int irq_idx = ENA_IO_IRQ_IDX(i);
> -
> -               rc = irq_cpu_rmap_add(adapter->netdev->rx_cpu_rmap,
> -                                     pci_irq_vector(adapter->pdev, irq_idx));
> -               if (rc) {
> -                       free_irq_cpu_rmap(adapter->netdev->rx_cpu_rmap);
> -                       adapter->netdev->rx_cpu_rmap = NULL;
> -                       return rc;
> -               }
> -       }
> -#endif /* CONFIG_RFS_ACCEL */
> +       return netif_enable_cpu_rmap(adapter->netdev,
> +adapter->num_io_queues); #else
>         return 0;
> +#endif /* CONFIG_RFS_ACCEL */
>  }
> 
>  static void ena_init_io_rings_common(struct ena_adapter *adapter, @@ -
> 1742,13 +1724,6 @@ static void ena_free_io_irq(struct ena_adapter
> *adapter)
>         struct ena_irq *irq;
>         int i;
> 
> -#ifdef CONFIG_RFS_ACCEL
> -       if (adapter->msix_vecs >= 1) {
> -               free_irq_cpu_rmap(adapter->netdev->rx_cpu_rmap);
> -               adapter->netdev->rx_cpu_rmap = NULL;
> -       }
> -#endif /* CONFIG_RFS_ACCEL */
> -
>         for (i = ENA_IO_IRQ_FIRST_IDX; i <
> ENA_MAX_MSIX_VEC(io_queue_count); i++) {
>                 irq = &adapter->irq_tbl[i];
>                 irq_set_affinity_hint(irq->vector, NULL); @@ -4131,13 +4106,6 @@
> static void __ena_shutoff(struct pci_dev *pdev, bool shutdown)
>         ena_dev = adapter->ena_dev;
>         netdev = adapter->netdev;
> 
> -#ifdef CONFIG_RFS_ACCEL
> -       if ((adapter->msix_vecs >= 1) && (netdev->rx_cpu_rmap)) {
> -               free_irq_cpu_rmap(netdev->rx_cpu_rmap);
> -               netdev->rx_cpu_rmap = NULL;
> -       }
> -
> -#endif /* CONFIG_RFS_ACCEL */
>         /* Make sure timer and reset routine won't be called after
>          * freeing device resources.
>          */
> diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> index 884d42db5554..1f50bc715038 100644
> --- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> @@ -49,7 +49,6 @@
>  #include <linux/cache.h>
>  #include <linux/log2.h>
>  #include <linux/bitmap.h>
> -#include <linux/cpu_rmap.h>
>  #include <linux/cpumask.h>
>  #include <net/pkt_cls.h>
>  #include <net/page_pool/helpers.h>
> @@ -10861,7 +10860,7 @@ static int bnxt_set_real_num_queues(struct bnxt
> *bp)
> 
>  #ifdef CONFIG_RFS_ACCEL
>         if (bp->flags & BNXT_FLAG_RFS)
> -               dev->rx_cpu_rmap = alloc_irq_cpu_rmap(bp->rx_nr_rings);
> +               return netif_enable_cpu_rmap(dev, bp->rx_nr_rings);
>  #endif
> 
>         return rc;
> @@ -11215,10 +11214,6 @@ static void bnxt_free_irq(struct bnxt *bp)
>         struct bnxt_irq *irq;
>         int i;
> 
> -#ifdef CONFIG_RFS_ACCEL
> -       free_irq_cpu_rmap(bp->dev->rx_cpu_rmap);
> -       bp->dev->rx_cpu_rmap = NULL;
> -#endif
>         if (!bp->irq_tbl || !bp->bnapi)
>                 return;
> 
> @@ -11241,11 +11236,8 @@ static void bnxt_free_irq(struct bnxt *bp)
> 
>  static int bnxt_request_irq(struct bnxt *bp)  {
> -       int i, j, rc = 0;
> +       int i, rc = 0;
>         unsigned long flags = 0;
> -#ifdef CONFIG_RFS_ACCEL
> -       struct cpu_rmap *rmap;
> -#endif
> 
>         rc = bnxt_setup_int_mode(bp);
>         if (rc) {
> @@ -11253,22 +11245,11 @@ static int bnxt_request_irq(struct bnxt *bp)
>                            rc);
>                 return rc;
>         }
> -#ifdef CONFIG_RFS_ACCEL
> -       rmap = bp->dev->rx_cpu_rmap;
> -#endif
> -       for (i = 0, j = 0; i < bp->cp_nr_rings; i++) {
> +
> +       for (i = 0; i < bp->cp_nr_rings; i++) {
>                 int map_idx = bnxt_cp_num_to_irq_num(bp, i);
>                 struct bnxt_irq *irq = &bp->irq_tbl[map_idx];
> 
> -#ifdef CONFIG_RFS_ACCEL
> -               if (rmap && bp->bnapi[i]->rx_ring) {
> -                       rc = irq_cpu_rmap_add(rmap, irq->vector);
> -                       if (rc)
> -                               netdev_warn(bp->dev, "failed adding irq rmap for ring
> %d\n",
> -                                           j);
> -                       j++;
> -               }
> -#endif
>                 rc = request_irq(irq->vector, irq->handler, flags, irq->name,
>                                  bp->bnapi[i]);
>                 if (rc)
> diff --git a/drivers/net/ethernet/intel/ice/ice_arfs.c
> b/drivers/net/ethernet/intel/ice/ice_arfs.c
> index 7cee365cc7d1..3b1b892e6958 100644
> --- a/drivers/net/ethernet/intel/ice/ice_arfs.c
> +++ b/drivers/net/ethernet/intel/ice/ice_arfs.c
> @@ -584,9 +584,6 @@ void ice_free_cpu_rx_rmap(struct ice_vsi *vsi)
>         netdev = vsi->netdev;
>         if (!netdev || !netdev->rx_cpu_rmap)
>                 return;
> -
> -       free_irq_cpu_rmap(netdev->rx_cpu_rmap);
> -       netdev->rx_cpu_rmap = NULL;
>  }
> 
>  /**
> @@ -597,7 +594,6 @@ int ice_set_cpu_rx_rmap(struct ice_vsi *vsi)  {
>         struct net_device *netdev;
>         struct ice_pf *pf;
> -       int i;
> 
>         if (!vsi || vsi->type != ICE_VSI_PF)
>                 return 0;
> @@ -610,18 +606,7 @@ int ice_set_cpu_rx_rmap(struct ice_vsi *vsi)
>         netdev_dbg(netdev, "Setup CPU RMAP: vsi type 0x%x, ifname %s,
> q_vectors %d\n",
>                    vsi->type, netdev->name, vsi->num_q_vectors);
> 
> -       netdev->rx_cpu_rmap = alloc_irq_cpu_rmap(vsi->num_q_vectors);
> -       if (unlikely(!netdev->rx_cpu_rmap))
> -               return -EINVAL;
> -
> -       ice_for_each_q_vector(vsi, i)
> -               if (irq_cpu_rmap_add(netdev->rx_cpu_rmap,
> -                                    vsi->q_vectors[i]->irq.virq)) {
> -                       ice_free_cpu_rx_rmap(vsi);
> -                       return -EINVAL;
> -               }
> -
> -       return 0;
> +       return netif_enable_cpu_rmap(netdev, vsi->num_q_vectors);
>  }
> 
>  /**
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index
> aeb4a6cff171..7e95e9ee36dd 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -1991,6 +1991,9 @@ enum netdev_reg_state {
>   *
>   *     @threaded:      napi threaded mode is enabled
>   *
> + *     @rx_cpu_rmap_auto: driver wants the core to manage the ARFS rmap.
> + *                        Set by calling netif_enable_cpu_rmap().
> + *
>   *     @see_all_hwtstamp_requests: device wants to see calls to
>   *                     ndo_hwtstamp_set() for all timestamp requests
>   *                     regardless of source, even if those aren't
> @@ -2398,6 +2401,9 @@ struct net_device {
>         struct lock_class_key   *qdisc_tx_busylock;
>         bool                    proto_down;
>         bool                    threaded;
> +#ifdef CONFIG_RFS_ACCEL
> +       bool                    rx_cpu_rmap_auto;
> +#endif
> 
>         /* priv_flags_slow, ungrouped to save space */
>         unsigned long           see_all_hwtstamp_requests:1;
> @@ -2671,10 +2677,7 @@ void netif_queue_set_napi(struct net_device
> *dev, unsigned int queue_index,
>                           enum netdev_queue_type type,
>                           struct napi_struct *napi);
> 
> -static inline void netif_napi_set_irq(struct napi_struct *napi, int irq) -{
> -       napi->irq = irq;
> -}
> +void netif_napi_set_irq(struct napi_struct *napi, int irq);
> 
>  /* Default NAPI poll() weight
>   * Device drivers are strongly advised to not use bigger value @@ -2765,6
> +2768,10 @@ static inline void netif_napi_del(struct napi_struct *napi)
>         synchronize_net();
>  }
> 
> +#ifdef CONFIG_RFS_ACCEL
> +int netif_enable_cpu_rmap(struct net_device *dev, unsigned int
> +num_irqs);
> +
> +#endif
>  struct packet_type {
>         __be16                  type;   /* This is really htons(ether_type). */
>         bool                    ignore_outgoing;
> diff --git a/net/core/dev.c b/net/core/dev.c index
> 1a90ed8cc6cc..3ee7a514dca8 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -6745,6 +6745,46 @@ void netif_queue_set_napi(struct net_device
> *dev, unsigned int queue_index,  }
> EXPORT_SYMBOL(netif_queue_set_napi);
> 
> +#ifdef CONFIG_RFS_ACCEL
> +static void netif_disable_cpu_rmap(struct net_device *dev) {
> +       free_irq_cpu_rmap(dev->rx_cpu_rmap);
> +       dev->rx_cpu_rmap = NULL;
> +       dev->rx_cpu_rmap_auto = false;
> +}
> +
> +int netif_enable_cpu_rmap(struct net_device *dev, unsigned int
> +num_irqs) {
> +       dev->rx_cpu_rmap = alloc_irq_cpu_rmap(num_irqs);
> +       if (!dev->rx_cpu_rmap)
> +               return -ENOMEM;
> +
> +       dev->rx_cpu_rmap_auto = true;
> +       return 0;
> +}
> +EXPORT_SYMBOL(netif_enable_cpu_rmap);
> +#endif
> +
> +void netif_napi_set_irq(struct napi_struct *napi, int irq) { #ifdef
> +CONFIG_RFS_ACCEL
> +       int rc;
> +#endif
> +       napi->irq = irq;
> +
> +#ifdef CONFIG_RFS_ACCEL
> +       if (napi->dev->rx_cpu_rmap && napi->dev->rx_cpu_rmap_auto) {
> +               rc = irq_cpu_rmap_add(napi->dev->rx_cpu_rmap, irq);
> +               if (rc) {
> +                       netdev_warn(napi->dev, "Unable to update ARFS map (%d)\n",
> +                                   rc);
> +                       netif_disable_cpu_rmap(napi->dev);
> +               }
> +       }
> +#endif
> +}
> +EXPORT_SYMBOL(netif_napi_set_irq);
> +
>  static void napi_restore_config(struct napi_struct *n)  {
>         n->defer_hard_irqs = n->config->defer_hard_irqs; @@ -11421,6
> +11461,10 @@ void free_netdev(struct net_device *dev)
>         /* Flush device addresses */
>         dev_addr_flush(dev);
> 
> +#ifdef CONFIG_RFS_ACCEL
> +       if (dev->rx_cpu_rmap && dev->rx_cpu_rmap_auto)
> +               netif_disable_cpu_rmap(dev); #endif
>         list_for_each_entry_safe(p, n, &dev->napi_list, dev_list)
>                 netif_napi_del(p);
> 
> --
> 2.43.0

Thanks for making the change in the ENA driver.

Acked-by: David Arinzon <darinzon@amazon.com>

Re: [PATCH net-next v5 1/6] net: move ARFS rmap management to core

[Jakub Kicinski]

On Mon, 13 Jan 2025 10:10:37 -0700 Ahmed Zaki wrote:
> -#endif /* CONFIG_RFS_ACCEL */
> +	return netif_enable_cpu_rmap(adapter->netdev, adapter->num_io_queues);
> +#else
>  	return 0;
> +#endif /* CONFIG_RFS_ACCEL */

Let's try to eliminate some of the ifdef-ery on the driver side.
netif_enable_cpu_rmap() should simply do nothing if !CONFIG_RFS_ACCEL

> @@ -2398,6 +2401,9 @@ struct net_device {
> 	struct lock_class_key	*qdisc_tx_busylock;
> 	bool			proto_down;
> 	bool			threaded;
> +#ifdef CONFIG_RFS_ACCEL
> +	bool			rx_cpu_rmap_auto;
> +#endif

similar point, don't hide it, it's just one byte and we can just leave
it as false if !CONFIG_RFS_ACCEL. It can save us a bunch of other ifdefs

> +#ifdef CONFIG_RFS_ACCEL
> +static void netif_disable_cpu_rmap(struct net_device *dev)
> +{
> +	free_irq_cpu_rmap(dev->rx_cpu_rmap);
> +	dev->rx_cpu_rmap = NULL;
> +	dev->rx_cpu_rmap_auto = false;
> +}

Better do do:

static void netif_disable_cpu_rmap(struct net_device *dev)
{
#ifdef CONFIG_RFS_ACCEL
	free_irq_cpu_rmap(dev->rx_cpu_rmap);
	dev->rx_cpu_rmap = NULL;
	dev->rx_cpu_rmap_auto = false;
#endif
}

IOW if not relevant the function should do nothing

> +int netif_enable_cpu_rmap(struct net_device *dev, unsigned int num_irqs)
> +{
> +	dev->rx_cpu_rmap = alloc_irq_cpu_rmap(num_irqs);
> +	if (!dev->rx_cpu_rmap)
> +		return -ENOMEM;
> +
> +	dev->rx_cpu_rmap_auto = true;
> +	return 0;
> +}
> +EXPORT_SYMBOL(netif_enable_cpu_rmap);

here you can depend on dead code elimination:

int netif_enable_cpu_rmap(struct net_device *dev, unsigned int num_irqs)
{
	if (!IS_ENABLED(CONFIG_RFS_ACCEL))
		return 0;

	...
}

> +#endif
> +
> +void netif_napi_set_irq(struct napi_struct *napi, int irq)
> +{
> +#ifdef CONFIG_RFS_ACCEL
> +	int rc;
> +#endif
> +	napi->irq = irq;
> +
> +#ifdef CONFIG_RFS_ACCEL
> +	if (napi->dev->rx_cpu_rmap && napi->dev->rx_cpu_rmap_auto) {
> +		rc = irq_cpu_rmap_add(napi->dev->rx_cpu_rmap, irq);
> +		if (rc) {
> +			netdev_warn(napi->dev, "Unable to update ARFS map (%d)\n",
> +				    rc);
> +			netif_disable_cpu_rmap(napi->dev);
> +		}
> +	}
> +#endif

Declare rc inside the if to avoid the extra ifdef on variable decl

> +}
> +EXPORT_SYMBOL(netif_napi_set_irq);
> +
>  static void napi_restore_config(struct napi_struct *n)
>  {
>  	n->defer_hard_irqs = n->config->defer_hard_irqs;
> @@ -11421,6 +11461,10 @@ void free_netdev(struct net_device *dev)
>  	/* Flush device addresses */
>  	dev_addr_flush(dev);
>  
> +#ifdef CONFIG_RFS_ACCEL
> +	if (dev->rx_cpu_rmap && dev->rx_cpu_rmap_auto)

don't check dev->rx_cpu_rmap, dev->rx_cpu_rmap_auto is enough

> +		netif_disable_cpu_rmap(dev);
> +#endif
>  	list_for_each_entry_safe(p, n, &dev->napi_list, dev_list)
>  		netif_napi_del(p);
>  

IRQs are often allocated in ndo_open and freed in ndo_stop, so
you need to catch netif_napi_del or napi_disable and remove
the IRQ from the map.

Similarly netif_napi_set_irq() may get called with -1 to clear
the IRQ number, which you currently treat at a real IRQ id, AFAICT.
-- 
pw-bot: cr

Re: [PATCH net-next v5 1/6] net: move ARFS rmap management to core

[Ahmed Zaki]

On 2025-01-14 3:08 p.m., Jakub Kicinski wrote:
> On Mon, 13 Jan 2025 10:10:37 -0700 Ahmed Zaki wrote:
>> -#endif /* CONFIG_RFS_ACCEL */
>> +	return netif_enable_cpu_rmap(adapter->netdev, adapter->num_io_queues);
>> +#else
>>   	return 0;
>> +#endif /* CONFIG_RFS_ACCEL */
> 
> Let's try to eliminate some of the ifdef-ery on the driver side.
> netif_enable_cpu_rmap() should simply do nothing if !CONFIG_RFS_ACCEL
> 
>> @@ -2398,6 +2401,9 @@ struct net_device {
>> 	struct lock_class_key	*qdisc_tx_busylock;
>> 	bool			proto_down;
>> 	bool			threaded;
>> +#ifdef CONFIG_RFS_ACCEL
>> +	bool			rx_cpu_rmap_auto;
>> +#endif
> 
> similar point, don't hide it, it's just one byte and we can just leave
> it as false if !CONFIG_RFS_ACCEL. It can save us a bunch of other ifdefs

Ok, makes sense.

> 
>> +#ifdef CONFIG_RFS_ACCEL
>> +static void netif_disable_cpu_rmap(struct net_device *dev)
>> +{
>> +	free_irq_cpu_rmap(dev->rx_cpu_rmap);
>> +	dev->rx_cpu_rmap = NULL;
>> +	dev->rx_cpu_rmap_auto = false;
>> +}
> 
> Better do do:
> 
> static void netif_disable_cpu_rmap(struct net_device *dev)
> {
> #ifdef CONFIG_RFS_ACCEL
> 	free_irq_cpu_rmap(dev->rx_cpu_rmap);
> 	dev->rx_cpu_rmap = NULL;
> 	dev->rx_cpu_rmap_auto = false;
> #endif
> }

Sure.

> 
> IOW if not relevant the function should do nothing
> 
>> +int netif_enable_cpu_rmap(struct net_device *dev, unsigned int num_irqs)
>> +{
>> +	dev->rx_cpu_rmap = alloc_irq_cpu_rmap(num_irqs);
>> +	if (!dev->rx_cpu_rmap)
>> +		return -ENOMEM;
>> +
>> +	dev->rx_cpu_rmap_auto = true;
>> +	return 0;
>> +}
>> +EXPORT_SYMBOL(netif_enable_cpu_rmap);
> 
> here you can depend on dead code elimination:
> 
> int netif_enable_cpu_rmap(struct net_device *dev, unsigned int num_irqs)
> {
> 	if (!IS_ENABLED(CONFIG_RFS_ACCEL))
> 		return 0;
> 
> 	...
> }
> 

netdev->rx_cpu_rmap is declared inside #ifdef CONFIG_RFS_ACCEL, so I 
still need #ifdef inside netif_enable_cpu_rmap(). I will do the same as
in netif_disable_cpu_rmap() though, that will keep the function visible.

>> +#endif
>> +
>> +void netif_napi_set_irq(struct napi_struct *napi, int irq)
>> +{
>> +#ifdef CONFIG_RFS_ACCEL
>> +	int rc;
>> +#endif
>> +	napi->irq = irq;
>> +
>> +#ifdef CONFIG_RFS_ACCEL
>> +	if (napi->dev->rx_cpu_rmap && napi->dev->rx_cpu_rmap_auto) {
>> +		rc = irq_cpu_rmap_add(napi->dev->rx_cpu_rmap, irq);
>> +		if (rc) {
>> +			netdev_warn(napi->dev, "Unable to update ARFS map (%d)\n",
>> +				    rc);
>> +			netif_disable_cpu_rmap(napi->dev);
>> +		}
>> +	}
>> +#endif
> 
> Declare rc inside the if to avoid the extra ifdef on variable decl

The CONFIG_RFS_ACCEL is removed in a later patch (3) when the 
irq_affinity_auto is introduced and rc is re-used.

Instead, I will move "napi->irq = irq;" to the end and merge the 2 
RFS_ACCL blocks.

> 
>> +}
>> +EXPORT_SYMBOL(netif_napi_set_irq);
>> +
>>   static void napi_restore_config(struct napi_struct *n)
>>   {
>>   	n->defer_hard_irqs = n->config->defer_hard_irqs;
>> @@ -11421,6 +11461,10 @@ void free_netdev(struct net_device *dev)
>>   	/* Flush device addresses */
>>   	dev_addr_flush(dev);
>>   
>> +#ifdef CONFIG_RFS_ACCEL
>> +	if (dev->rx_cpu_rmap && dev->rx_cpu_rmap_auto)
> 
> don't check dev->rx_cpu_rmap, dev->rx_cpu_rmap_auto is enough

yes, also a good point.


> 
>> +		netif_disable_cpu_rmap(dev);
>> +#endif
>>   	list_for_each_entry_safe(p, n, &dev->napi_list, dev_list)
>>   		netif_napi_del(p);
>>   
> 
> IRQs are often allocated in ndo_open and freed in ndo_stop, so
> you need to catch netif_napi_del or napi_disable and remove
> the IRQ from the map.

Ok, I will look into that too.

> 
> Similarly netif_napi_set_irq() may get called with -1 to clear
> the IRQ number, which you currently treat at a real IRQ id, AFAICT.

correct there is no handling for irq = -1. So netif_napi_set_irq() needs 
to add the irq to the rmap only if it is > 0.

I need to clarify expectation of netif_napi_set_irq() because I only see 
it called with irq = -1 in napi_add_weight. But you say it can be called 
with irq = -1 to "clear" the IRQ.

Does this mean that, if irq = -1, we need to "delete" the irq from rmap 
if a valid irq already existed (which means this can happen as an 
alternative to napi_del()/napi_diable())? or just skip adding irq to 
rmap is enough?

Thanks,
Ahmed

Re: [PATCH net-next v5 1/6] net: move ARFS rmap management to core

[Jakub Kicinski]

On Tue, 14 Jan 2025 18:00:30 -0700 Ahmed Zaki wrote:
> > Similarly netif_napi_set_irq() may get called with -1 to clear
> > the IRQ number, which you currently treat at a real IRQ id, AFAICT.  
> 
> correct there is no handling for irq = -1. So netif_napi_set_irq() needs 
> to add the irq to the rmap only if it is > 0.
> 
> I need to clarify expectation of netif_napi_set_irq() because I only see 
> it called with irq = -1 in napi_add_weight. But you say it can be called 
> with irq = -1 to "clear" the IRQ.

I _think_ that's what Amritha had in mind. For queue <> NAPI linking
similarly we are expected to call the same helper with a NULL param.

> Does this mean that, if irq = -1, we need to "delete" the irq from rmap 
> if a valid irq already existed (which means this can happen as an 
> alternative to napi_del()/napi_diable())? or just skip adding irq to 
> rmap is enough?

I'm afraid we need both. Most drivers today simply never clear the IRQ,
they will just delete the NAPI and kfree() its memory. So we need to
"catch" NAPIs with IRQs assigned getting deleted and clean up the IRQ.

In the future some drivers may explicitly call the set with -1,
especially now that the IRQ has more implications than just getting
reported via netlink. We need to support that, too.

And for a good measure we should also throw in a warning if a driver
tries to set the IRQ but the IRQ is already set in the NAPI (not -1).