Add a cached FID bitmap. This mitigates the need to walk all VTU entries
to find the next free FID.

When flushing the VTU (during init), zero the FID bitmap. Use and
manipulate this bitmap from now on, instead of reading HW for the FID
map.

The repeated VTU walks are costly and can take ~40 mins if ~4000 vlans
are added. Caching the FID map reduces this time to <2 mins.

Signed-off-by: Aryan Srivastava <aryan.srivastava@alliedtelesis.co.nz>
---
Changes in v1:
- Moved initial HW walk to setup

Changes in v2:
- Removed inital HW walk
- Purge cached FID when VTU is flushed

 drivers/net/dsa/mv88e6xxx/chip.c        | 35 +++++--------------------
 drivers/net/dsa/mv88e6xxx/chip.h        |  5 ++--
 drivers/net/dsa/mv88e6xxx/devlink.c     |  9 +------
 drivers/net/dsa/mv88e6xxx/global1_vtu.c |  3 +++
 4 files changed, 14 insertions(+), 38 deletions(-)

diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index ddc832e33f4b..f68233d24f32 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c
@@ -1930,36 +1930,9 @@ static int mv88e6xxx_vtu_loadpurge(struct mv88e6xxx_chip *chip,
 	return chip->info->ops->vtu_loadpurge(chip, entry);
 }
 
-static int mv88e6xxx_fid_map_vlan(struct mv88e6xxx_chip *chip,
-				  const struct mv88e6xxx_vtu_entry *entry,
-				  void *_fid_bitmap)
-{
-	unsigned long *fid_bitmap = _fid_bitmap;
-
-	set_bit(entry->fid, fid_bitmap);
-	return 0;
-}
-
-int mv88e6xxx_fid_map(struct mv88e6xxx_chip *chip, unsigned long *fid_bitmap)
-{
-	bitmap_zero(fid_bitmap, MV88E6XXX_N_FID);
-
-	/* Every FID has an associated VID, so walking the VTU
-	 * will discover the full set of FIDs in use.
-	 */
-	return mv88e6xxx_vtu_walk(chip, mv88e6xxx_fid_map_vlan, fid_bitmap);
-}
-
 static int mv88e6xxx_atu_new(struct mv88e6xxx_chip *chip, u16 *fid)
 {
-	DECLARE_BITMAP(fid_bitmap, MV88E6XXX_N_FID);
-	int err;
-
-	err = mv88e6xxx_fid_map(chip, fid_bitmap);
-	if (err)
-		return err;
-
-	*fid = find_first_zero_bit(fid_bitmap, MV88E6XXX_N_FID);
+	*fid = find_first_zero_bit(chip->fid_bitmap, MV88E6XXX_N_FID);
 	if (unlikely(*fid >= mv88e6xxx_num_databases(chip)))
 		return -ENOSPC;
 
@@ -2666,6 +2639,9 @@ static int mv88e6xxx_port_vlan_join(struct mv88e6xxx_chip *chip, int port,
 			 port, vid);
 	}
 
+	/* Record FID used in SW FID map */
+	bitmap_set(chip->fid_bitmap, vlan.fid, 1);
+
 	return 0;
 }
 
@@ -2771,6 +2747,9 @@ static int mv88e6xxx_port_vlan_leave(struct mv88e6xxx_chip *chip,
 		err = mv88e6xxx_mst_put(chip, vlan.sid);
 		if (err)
 			return err;
+
+		/* Record FID freed in SW FID map */
+		bitmap_clear(chip->fid_bitmap, vlan.fid, 1);
 	}
 
 	return mv88e6xxx_g1_atu_remove(chip, vlan.fid, port, false);
diff --git a/drivers/net/dsa/mv88e6xxx/chip.h b/drivers/net/dsa/mv88e6xxx/chip.h
index 8b07e7d83589..00aa59857b64 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.h
+++ b/drivers/net/dsa/mv88e6xxx/chip.h
@@ -440,6 +440,9 @@ struct mv88e6xxx_chip {
 
 	/* Bridge MST to SID mappings */
 	struct list_head msts;
+
+	/* FID map */
+	DECLARE_BITMAP(fid_bitmap, MV88E6XXX_N_FID);
 };
 
 struct mv88e6xxx_bus_ops {
@@ -843,6 +846,4 @@ int mv88e6xxx_vtu_walk(struct mv88e6xxx_chip *chip,
 				 void *priv),
 		       void *priv);
 
-int mv88e6xxx_fid_map(struct mv88e6xxx_chip *chip, unsigned long *bitmap);
-
 #endif /* _MV88E6XXX_CHIP_H */
diff --git a/drivers/net/dsa/mv88e6xxx/devlink.c b/drivers/net/dsa/mv88e6xxx/devlink.c
index a08dab75e0c0..ef3643bc43db 100644
--- a/drivers/net/dsa/mv88e6xxx/devlink.c
+++ b/drivers/net/dsa/mv88e6xxx/devlink.c
@@ -374,7 +374,6 @@ static int mv88e6xxx_region_atu_snapshot(struct devlink *dl,
 					 u8 **data)
 {
 	struct dsa_switch *ds = dsa_devlink_to_ds(dl);
-	DECLARE_BITMAP(fid_bitmap, MV88E6XXX_N_FID);
 	struct mv88e6xxx_devlink_atu_entry *table;
 	struct mv88e6xxx_chip *chip = ds->priv;
 	int fid = -1, count, err;
@@ -392,14 +391,8 @@ static int mv88e6xxx_region_atu_snapshot(struct devlink *dl,
 
 	mv88e6xxx_reg_lock(chip);
 
-	err = mv88e6xxx_fid_map(chip, fid_bitmap);
-	if (err) {
-		kfree(table);
-		goto out;
-	}
-
 	while (1) {
-		fid = find_next_bit(fid_bitmap, MV88E6XXX_N_FID, fid + 1);
+		fid = find_next_bit(chip->fid_bitmap, MV88E6XXX_N_FID, fid + 1);
 		if (fid == MV88E6XXX_N_FID)
 			break;
 
diff --git a/drivers/net/dsa/mv88e6xxx/global1_vtu.c b/drivers/net/dsa/mv88e6xxx/global1_vtu.c
index bcfb4a812055..b524f27a2f0d 100644
--- a/drivers/net/dsa/mv88e6xxx/global1_vtu.c
+++ b/drivers/net/dsa/mv88e6xxx/global1_vtu.c
@@ -471,6 +471,9 @@ int mv88e6xxx_g1_vtu_flush(struct mv88e6xxx_chip *chip)
 {
 	int err;
 
+	/* As part of the VTU flush, refresh FID map */
+	bitmap_zero(chip->fid_bitmap, MV88E6XXX_N_FID);
+
 	err = mv88e6xxx_g1_vtu_op_wait(chip);
 	if (err)
 		return err;
-- 
2.46.0

On Mon, Oct 07, 2024 at 10:29:05AM +1300, Aryan Srivastava wrote:
> Add a cached FID bitmap. This mitigates the need to walk all VTU entries
> to find the next free FID.
> 
> When flushing the VTU (during init), zero the FID bitmap. Use and
> manipulate this bitmap from now on, instead of reading HW for the FID
> map.
> 
> The repeated VTU walks are costly and can take ~40 mins if ~4000 vlans
> are added. Caching the FID map reduces this time to <2 mins.
> 
> Signed-off-by: Aryan Srivastava <aryan.srivastava@alliedtelesis.co.nz>

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew