diff mbox series

[v5,net-next,06/10] net: dsa: lantiq_gswip: serialize access to the PCE registers

Message ID 20211024171757.3753288-7-vladimir.oltean@nxp.com (mailing list archive)
State Accepted
Commit cf231b436f7ceaf0d87016eedf830677c0c1f7dc
Delegated to: Netdev Maintainers
Headers show
Series Drop rtnl_lock from DSA .port_fdb_{add,del} | expand

Checks

Context Check Description
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netdev/fixes_present success Fixes tag not required for -next series
netdev/patch_count success Link
netdev/tree_selection success Clearly marked for net-next
netdev/subject_prefix success Link
netdev/cc_maintainers warning 3 maintainers not CCed: linux-arm-kernel@lists.infradead.org linux-mediatek@lists.infradead.org matthias.bgg@gmail.com
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/verify_fixes success No Fixes tag
netdev/checkpatch warning CHECK: struct mutex definition without comment
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/header_inline success No static functions without inline keyword in header files

Commit Message

Vladimir Oltean Oct. 24, 2021, 5:17 p.m. UTC 
The GSWIP switch accesses various bridging layer tables (VLANs, FDBs,
forwarding rules) indirectly through PCE registers. These hardware
accesses are non-atomic, being comprised of several register reads and
writes.

These accesses are currently serialized by the rtnl_lock, but DSA is
changing its driver API and that lock will no longer be held when
calling ->port_fdb_add() and ->port_fdb_del().

So this driver needs to serialize the access to the PCE registers using
its own locking scheme. This patch adds that.

Note that the driver also uses the gswip_pce_load_microcode() function
to load a static configuration for the packet classification engine into
a table using the same registers. It is currently not protected, but
since that configuration is only done from the dsa_switch_ops :: setup
method, there is no risk of it being concurrent with other operations.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Acked-by: Hauke Mehrtens <hauke@hauke-m.de>
---
v3->v4: call mutex_init
v4->v5: slightly reword the commit message according to Hauke's indications

 drivers/net/dsa/lantiq_gswip.c | 28 +++++++++++++++++++++++-----
 1 file changed, 23 insertions(+), 5 deletions(-)
diff mbox series

Patch

diff --git a/drivers/net/dsa/lantiq_gswip.c b/drivers/net/dsa/lantiq_gswip.c
index dbd4486a173f..1a96df70d1e8 100644
--- a/drivers/net/dsa/lantiq_gswip.c
+++ b/drivers/net/dsa/lantiq_gswip.c
@@ -276,6 +276,7 @@  struct gswip_priv {
 	int num_gphy_fw;
 	struct gswip_gphy_fw *gphy_fw;
 	u32 port_vlan_filter;
+	struct mutex pce_table_lock;
 };
 
 struct gswip_pce_table_entry {
@@ -523,10 +524,14 @@  static int gswip_pce_table_entry_read(struct gswip_priv *priv,
 	u16 addr_mode = tbl->key_mode ? GSWIP_PCE_TBL_CTRL_OPMOD_KSRD :
 					GSWIP_PCE_TBL_CTRL_OPMOD_ADRD;
 
+	mutex_lock(&priv->pce_table_lock);
+
 	err = gswip_switch_r_timeout(priv, GSWIP_PCE_TBL_CTRL,
 				     GSWIP_PCE_TBL_CTRL_BAS);
-	if (err)
+	if (err) {
+		mutex_unlock(&priv->pce_table_lock);
 		return err;
+	}
 
 	gswip_switch_w(priv, tbl->index, GSWIP_PCE_TBL_ADDR);
 	gswip_switch_mask(priv, GSWIP_PCE_TBL_CTRL_ADDR_MASK |
@@ -536,8 +541,10 @@  static int gswip_pce_table_entry_read(struct gswip_priv *priv,
 
 	err = gswip_switch_r_timeout(priv, GSWIP_PCE_TBL_CTRL,
 				     GSWIP_PCE_TBL_CTRL_BAS);
-	if (err)
+	if (err) {
+		mutex_unlock(&priv->pce_table_lock);
 		return err;
+	}
 
 	for (i = 0; i < ARRAY_SIZE(tbl->key); i++)
 		tbl->key[i] = gswip_switch_r(priv, GSWIP_PCE_TBL_KEY(i));
@@ -553,6 +560,8 @@  static int gswip_pce_table_entry_read(struct gswip_priv *priv,
 	tbl->valid = !!(crtl & GSWIP_PCE_TBL_CTRL_VLD);
 	tbl->gmap = (crtl & GSWIP_PCE_TBL_CTRL_GMAP_MASK) >> 7;
 
+	mutex_unlock(&priv->pce_table_lock);
+
 	return 0;
 }
 
@@ -565,10 +574,14 @@  static int gswip_pce_table_entry_write(struct gswip_priv *priv,
 	u16 addr_mode = tbl->key_mode ? GSWIP_PCE_TBL_CTRL_OPMOD_KSWR :
 					GSWIP_PCE_TBL_CTRL_OPMOD_ADWR;
 
+	mutex_lock(&priv->pce_table_lock);
+
 	err = gswip_switch_r_timeout(priv, GSWIP_PCE_TBL_CTRL,
 				     GSWIP_PCE_TBL_CTRL_BAS);
-	if (err)
+	if (err) {
+		mutex_unlock(&priv->pce_table_lock);
 		return err;
+	}
 
 	gswip_switch_w(priv, tbl->index, GSWIP_PCE_TBL_ADDR);
 	gswip_switch_mask(priv, GSWIP_PCE_TBL_CTRL_ADDR_MASK |
@@ -600,8 +613,12 @@  static int gswip_pce_table_entry_write(struct gswip_priv *priv,
 	crtl |= GSWIP_PCE_TBL_CTRL_BAS;
 	gswip_switch_w(priv, crtl, GSWIP_PCE_TBL_CTRL);
 
-	return gswip_switch_r_timeout(priv, GSWIP_PCE_TBL_CTRL,
-				      GSWIP_PCE_TBL_CTRL_BAS);
+	err = gswip_switch_r_timeout(priv, GSWIP_PCE_TBL_CTRL,
+				     GSWIP_PCE_TBL_CTRL_BAS);
+
+	mutex_unlock(&priv->pce_table_lock);
+
+	return err;
 }
 
 /* Add the LAN port into a bridge with the CPU port by
@@ -2106,6 +2123,7 @@  static int gswip_probe(struct platform_device *pdev)
 	priv->ds->priv = priv;
 	priv->ds->ops = priv->hw_info->ops;
 	priv->dev = dev;
+	mutex_init(&priv->pce_table_lock);
 	version = gswip_switch_r(priv, GSWIP_VERSION);
 
 	np = dev->of_node;