[PATCH net-next v3 0/2] net: phy: sfp/mdio-i2c: defer RollBall probe + fix mii_bus leak

[PATCH net-next v3 0/2] net: phy: sfp/mdio-i2c: defer RollBall probe + fix mii_bus leak

[Petr Wozniak]

This series resends the RollBall bridge probe deferral (a fix for the
regression in commit 8fe125892f40) and adds a related mii_bus leak fix.

Patch 1 fixes a pre-existing mii_bus leak in sfp_i2c_mdiobus_destroy()
that has been present since the helper was introduced in 2022. Patch 2's
new -ENODEV path destroys the MDIO bus via sfp_i2c_mdiobus_destroy(), so
patch 1 is a prerequisite to avoid leaking the bus on that path.

The v2 deferral patch was corrupted in transit and failed to apply; it is
regenerated here against current net-next with no functional change.

v3:
 - Resend: v2 defer patch was corrupted in transit and failed to apply
   (netdev/apply); regenerated against current net-next.
 - Fixed block comment style flagged by checkpatch. No functional change.
 - Added patch 1/2 (sfp: free mii_bus in sfp_i2c_mdiobus_destroy).
v2 (defer):
 - Generalized scope: regression affects boot-inserted and hotplugged
   modules where bridge init exceeds 200 ms; Aleksander Bajkowski
   confirmed FLYPRO SFP-10GT-CS-30M / AQR113C broken when hotplugged.
 - Corrected state machine description (probe runs in SFP_S_INIT after
   SFP_S_WAIT) - Jan Hoffmann.
 - No code changes from v1.
v1: initial submission.

Petr Wozniak (2):
  net: phy: sfp: free mii_bus in sfp_i2c_mdiobus_destroy
  net: phy: mdio-i2c: defer RollBall bridge probe to PHY discovery

 drivers/net/mdio/mdio-i2c.c   | 15 +++++++++------
 drivers/net/phy/sfp.c         | 23 ++++++++++++++---------
 include/linux/mdio/mdio-i2c.h |  1 +
 3 files changed, 24 insertions(+), 15 deletions(-)


base-commit: b85966adbf5de0668a815c6e3527f87e0c387fb4
-- 
2.51.0

[PATCH net-next v3 1/2] net: phy: sfp: free mii_bus in sfp_i2c_mdiobus_destroy

[Petr Wozniak]

sfp_i2c_mdiobus_create() allocates the I2C MDIO bus with mdio_i2c_alloc(),
a plain (non-devm) allocation, and registers it. sfp_i2c_mdiobus_destroy()
only unregisters the bus and clears sfp->i2c_mii without calling
mdiobus_free(). As the only reference to the bus is then cleared, the
struct mii_bus is leaked.

This is hit whenever a copper/RollBall SFP module that instantiated an MDIO
bus is removed: sfp_sm_main() takes the global teardown path and calls
sfp_i2c_mdiobus_destroy(). sfp_cleanup(), on driver unbind, frees
sfp->i2c_mii directly, which is why the leak only triggered on module
hot-removal and not on unbind.

Free the bus in sfp_i2c_mdiobus_destroy() to match the allocation done in
sfp_i2c_mdiobus_create().

Fixes: e85b1347ace6 ("net: sfp: create/destroy I2C mdiobus before PHY probe/after PHY release")
Signed-off-by: Petr Wozniak <petr.wozniak@gmail.com>
---
 drivers/net/phy/sfp.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/phy/sfp.c b/drivers/net/phy/sfp.c
index 03bfd8640db9..c4d274ab651e 100644
--- a/drivers/net/phy/sfp.c
+++ b/drivers/net/phy/sfp.c
@@ -963,6 +963,7 @@ static int sfp_i2c_mdiobus_create(struct sfp *sfp)
 static void sfp_i2c_mdiobus_destroy(struct sfp *sfp)
 {
 	mdiobus_unregister(sfp->i2c_mii);
+	mdiobus_free(sfp->i2c_mii);
 	sfp->i2c_mii = NULL;
 }
 
-- 
2.51.0

Re: [PATCH net-next v3 1/2] net: phy: sfp: free mii_bus in sfp_i2c_mdiobus_destroy

[Maxime Chevallier]

On 6/23/26 10:05, Petr Wozniak wrote:
> sfp_i2c_mdiobus_create() allocates the I2C MDIO bus with mdio_i2c_alloc(),
> a plain (non-devm) allocation, and registers it. sfp_i2c_mdiobus_destroy()
> only unregisters the bus and clears sfp->i2c_mii without calling
> mdiobus_free(). As the only reference to the bus is then cleared, the
> struct mii_bus is leaked.
> 
> This is hit whenever a copper/RollBall SFP module that instantiated an MDIO
> bus is removed: sfp_sm_main() takes the global teardown path and calls
> sfp_i2c_mdiobus_destroy(). sfp_cleanup(), on driver unbind, frees
> sfp->i2c_mii directly, which is why the leak only triggered on module
> hot-removal and not on unbind.

which is worse, this can happen many times in a row :)

> 
> Free the bus in sfp_i2c_mdiobus_destroy() to match the allocation done in
> sfp_i2c_mdiobus_create().
> 
> Fixes: e85b1347ace6 ("net: sfp: create/destroy I2C mdiobus before PHY probe/after PHY release")
> Signed-off-by: Petr Wozniak <petr.wozniak@gmail.com>

With this patch sent towards the -net tree,

Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>

Maxime

> ---
>  drivers/net/phy/sfp.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/net/phy/sfp.c b/drivers/net/phy/sfp.c
> index 03bfd8640db9..c4d274ab651e 100644
> --- a/drivers/net/phy/sfp.c
> +++ b/drivers/net/phy/sfp.c
> @@ -963,6 +963,7 @@ static int sfp_i2c_mdiobus_create(struct sfp *sfp)
>  static void sfp_i2c_mdiobus_destroy(struct sfp *sfp)
>  {
>  	mdiobus_unregister(sfp->i2c_mii);
> +	mdiobus_free(sfp->i2c_mii);
>  	sfp->i2c_mii = NULL;
>  }
>  

[PATCH net-next v3 2/2] net: phy: mdio-i2c: defer RollBall bridge probe to PHY discovery

[Petr Wozniak]

commit 8fe125892f40 ("net: phy: sfp: probe for RollBall I2C-to-MDIO
bridge in mdio-i2c") introduced a regression: the RollBall I2C-to-MDIO
bridge is not yet ready to respond to CMD_READ/CMD_DONE cycles when
sfp_sm_add_mdio_bus() runs in SFP_S_INIT.  The 200 ms probe times out,
i2c_mii_probe_rollball() returns -ENODEV, and sfp_sm_add_mdio_bus()
sets mdio_protocol = MDIO_I2C_NONE.  By the time sfp_sm_probe_for_phy()
runs (up to ~17 s later on affected hardware), the bridge is fully
initialized but PHY probing is skipped because the protocol has already
been changed to NONE.

This affects both modules inserted before boot and hotplugged modules on
hardware where bridge initialization exceeds the 200 ms probe window
(confirmed: FLYPRO SFP-10GT-CS-30M with Aquantia AQR113C, hotplugged).

Move the probe from i2c_mii_init_rollball(), called at bus-creation time,
to sfp_sm_probe_for_phy() in sfp.c, where it runs after the SFP state
machine module initialization delays.  Export the probe function as
mdio_i2c_probe_rollball() so sfp.c can call it.

For RTL8261BE-based modules the probe correctly returns -ENODEV at PHY
discovery time, causing sfp_sm_probe_for_phy() to destroy the MDIO bus
and set MDIO_I2C_NONE, eliminating the 5+ minute PHY probe retry loop.

For genuine RollBall modules (e.g. FLYPRO SFP-10GT-CS-30M with Aquantia
AQR113C) the probe now runs after initialization is complete and
correctly returns 0, so PHY detection proceeds normally.

Reported-by: Aleksander Bajkowski <olek2@wp.pl>
Fixes: 8fe125892f40 ("net: phy: sfp: probe for RollBall I2C-to-MDIO bridge in mdio-i2c")
Signed-off-by: Petr Wozniak <petr.wozniak@gmail.com>
---
v3: regenerated against net-next (v2 failed to apply due to transit
    corruption); fixed block comment style (checkpatch); no functional
    change.
v2: commit message only - generalized scope (Aleksander Bajkowski);
    corrected SM description (Jan Hoffmann); no code change from v1.
v1: initial.
 drivers/net/mdio/mdio-i2c.c   | 15 +++++++++------
 drivers/net/phy/sfp.c         | 22 +++++++++++++---------
 include/linux/mdio/mdio-i2c.h |  1 +
 3 files changed, 23 insertions(+), 15 deletions(-)

diff --git a/drivers/net/mdio/mdio-i2c.c b/drivers/net/mdio/mdio-i2c.c
index b88f63234b4e..2a3a418c1369 100644
--- a/drivers/net/mdio/mdio-i2c.c
+++ b/drivers/net/mdio/mdio-i2c.c
@@ -419,7 +419,7 @@ static int i2c_mii_write_rollball(struct mii_bus *bus, int phy_id, int devad,
 	return 0;
 }
 
-static int i2c_mii_probe_rollball(struct i2c_adapter *i2c)
+int mdio_i2c_probe_rollball(struct i2c_adapter *i2c)
 {
 	u8 data_buf[] = { ROLLBALL_DATA_ADDR, 0x01, 0x00, 0x00 };
 	u8 cmd_buf[]  = { ROLLBALL_CMD_ADDR, ROLLBALL_CMD_READ };
@@ -462,9 +462,13 @@ static int i2c_mii_probe_rollball(struct i2c_adapter *i2c)
 
 	return -ENODEV;
 }
+EXPORT_SYMBOL_GPL(mdio_i2c_probe_rollball);
 
 static int i2c_mii_init_rollball(struct i2c_adapter *i2c)
 {
+	/* Send the RollBall unlock password; bridge presence is verified
+	 * later, in sfp_sm_probe_for_phy(), after module initialization.
+	 */
 	struct i2c_msg msg;
 	u8 pw[5];
 	int ret;
@@ -486,7 +490,7 @@ static int i2c_mii_init_rollball(struct i2c_adapter *i2c)
 	if (ret != 1)
 		return -EIO;
 
-	return i2c_mii_probe_rollball(i2c);
+	return 0;
 }
 
 static bool mdio_i2c_check_functionality(struct i2c_adapter *i2c,
@@ -531,10 +535,9 @@ struct mii_bus *mdio_i2c_alloc(struct device *parent, struct i2c_adapter *i2c,
 	case MDIO_I2C_ROLLBALL:
 		ret = i2c_mii_init_rollball(i2c);
 		if (ret < 0) {
-			if (ret != -ENODEV)
-				dev_err(parent,
-					"Cannot initialize RollBall MDIO I2C protocol: %d\n",
-					ret);
+			dev_err(parent,
+				"Cannot initialize RollBall MDIO I2C protocol: %d\n",
+				ret);
 			mdiobus_free(mii);
 			return ERR_PTR(ret);
 		}
diff --git a/drivers/net/phy/sfp.c b/drivers/net/phy/sfp.c
index c4d274ab651e..bbfaa0450798 100644
--- a/drivers/net/phy/sfp.c
+++ b/drivers/net/phy/sfp.c
@@ -2174,17 +2174,10 @@ static void sfp_sm_fault(struct sfp *sfp, unsigned int next_state, bool warn)
 
 static int sfp_sm_add_mdio_bus(struct sfp *sfp)
 {
-	int ret;
-
 	if (sfp->mdio_protocol == MDIO_I2C_NONE)
 		return 0;
 
-	ret = sfp_i2c_mdiobus_create(sfp);
-	if (ret == -ENODEV) {
-		sfp->mdio_protocol = MDIO_I2C_NONE;
-		return 0;
-	}
-	return ret;
+	return sfp_i2c_mdiobus_create(sfp);
 }
 
 /* Probe a SFP for a PHY device if the module supports copper - the PHY
@@ -2215,7 +2208,18 @@ static int sfp_sm_probe_for_phy(struct sfp *sfp)
 		break;
 
 	case MDIO_I2C_ROLLBALL:
-		err = sfp_sm_probe_phy(sfp, SFP_PHY_ADDR_ROLLBALL, true);
+		/* Probe here, after module initialization delays, so that
+		 * genuine RollBall bridges have had time to start up.
+		 * Modules without a bridge (e.g. RTL8261BE) return -ENODEV.
+		 */
+		err = mdio_i2c_probe_rollball(sfp->i2c);
+		if (err == -ENODEV) {
+			sfp_i2c_mdiobus_destroy(sfp);
+			sfp->mdio_protocol = MDIO_I2C_NONE;
+			break;
+		}
+		if (!err)
+			err = sfp_sm_probe_phy(sfp, SFP_PHY_ADDR_ROLLBALL, true);
 		break;
 	}
 
diff --git a/include/linux/mdio/mdio-i2c.h b/include/linux/mdio/mdio-i2c.h
index 65b550a6fc32..5cf14f45c94b 100644
--- a/include/linux/mdio/mdio-i2c.h
+++ b/include/linux/mdio/mdio-i2c.h
@@ -20,5 +20,6 @@ enum mdio_i2c_proto {
 
 struct mii_bus *mdio_i2c_alloc(struct device *parent, struct i2c_adapter *i2c,
 			       enum mdio_i2c_proto protocol);
+int mdio_i2c_probe_rollball(struct i2c_adapter *i2c);
 
 #endif
-- 
2.51.0

Re: [PATCH net-next v3 2/2] net: phy: mdio-i2c: defer RollBall bridge probe to PHY discovery

[Maxime Chevallier]

Hi Petr,

On 6/23/26 10:05, Petr Wozniak wrote:
> commit 8fe125892f40 ("net: phy: sfp: probe for RollBall I2C-to-MDIO
> bridge in mdio-i2c") introduced a regression: the RollBall I2C-to-MDIO
> bridge is not yet ready to respond to CMD_READ/CMD_DONE cycles when
> sfp_sm_add_mdio_bus() runs in SFP_S_INIT.  The 200 ms probe times out,
> i2c_mii_probe_rollball() returns -ENODEV, and sfp_sm_add_mdio_bus()
> sets mdio_protocol = MDIO_I2C_NONE.  By the time sfp_sm_probe_for_phy()
> runs (up to ~17 s later on affected hardware), the bridge is fully
> initialized but PHY probing is skipped because the protocol has already
> been changed to NONE.
> 
> This affects both modules inserted before boot and hotplugged modules on
> hardware where bridge initialization exceeds the 200 ms probe window
> (confirmed: FLYPRO SFP-10GT-CS-30M with Aquantia AQR113C, hotplugged).
> 
> Move the probe from i2c_mii_init_rollball(), called at bus-creation time,
> to sfp_sm_probe_for_phy() in sfp.c, where it runs after the SFP state
> machine module initialization delays.  Export the probe function as
> mdio_i2c_probe_rollball() so sfp.c can call it.
> 
> For RTL8261BE-based modules the probe correctly returns -ENODEV at PHY
> discovery time, causing sfp_sm_probe_for_phy() to destroy the MDIO bus
> and set MDIO_I2C_NONE, eliminating the 5+ minute PHY probe retry loop.
> 
> For genuine RollBall modules (e.g. FLYPRO SFP-10GT-CS-30M with Aquantia
> AQR113C) the probe now runs after initialization is complete and
> correctly returns 0, so PHY detection proceeds normally.
> 
> Reported-by: Aleksander Bajkowski <olek2@wp.pl>
> Fixes: 8fe125892f40 ("net: phy: sfp: probe for RollBall I2C-to-MDIO bridge in mdio-i2c")
> Signed-off-by: Petr Wozniak <petr.wozniak@gmail.com>

I'm not currently at home so I can't test that on my side, but as you'll
have to resend to the net tree, can you CC me for the next round so that
I can test with the few odd-ball modules I have ?

I expect to be able to test this on friday :(

Maxime

> ---
> v3: regenerated against net-next (v2 failed to apply due to transit
>     corruption); fixed block comment style (checkpatch); no functional
>     change.
> v2: commit message only - generalized scope (Aleksander Bajkowski);
>     corrected SM description (Jan Hoffmann); no code change from v1.
> v1: initial.
>  drivers/net/mdio/mdio-i2c.c   | 15 +++++++++------
>  drivers/net/phy/sfp.c         | 22 +++++++++++++---------
>  include/linux/mdio/mdio-i2c.h |  1 +
>  3 files changed, 23 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/net/mdio/mdio-i2c.c b/drivers/net/mdio/mdio-i2c.c
> index b88f63234b4e..2a3a418c1369 100644
> --- a/drivers/net/mdio/mdio-i2c.c
> +++ b/drivers/net/mdio/mdio-i2c.c
> @@ -419,7 +419,7 @@ static int i2c_mii_write_rollball(struct mii_bus *bus, int phy_id, int devad,
>  	return 0;
>  }
>  
> -static int i2c_mii_probe_rollball(struct i2c_adapter *i2c)
> +int mdio_i2c_probe_rollball(struct i2c_adapter *i2c)
>  {
>  	u8 data_buf[] = { ROLLBALL_DATA_ADDR, 0x01, 0x00, 0x00 };
>  	u8 cmd_buf[]  = { ROLLBALL_CMD_ADDR, ROLLBALL_CMD_READ };
> @@ -462,9 +462,13 @@ static int i2c_mii_probe_rollball(struct i2c_adapter *i2c)
>  
>  	return -ENODEV;
>  }
> +EXPORT_SYMBOL_GPL(mdio_i2c_probe_rollball);
>  
>  static int i2c_mii_init_rollball(struct i2c_adapter *i2c)
>  {
> +	/* Send the RollBall unlock password; bridge presence is verified
> +	 * later, in sfp_sm_probe_for_phy(), after module initialization.
> +	 */
>  	struct i2c_msg msg;
>  	u8 pw[5];
>  	int ret;
> @@ -486,7 +490,7 @@ static int i2c_mii_init_rollball(struct i2c_adapter *i2c)
>  	if (ret != 1)
>  		return -EIO;
>  
> -	return i2c_mii_probe_rollball(i2c);
> +	return 0;
>  }
>  
>  static bool mdio_i2c_check_functionality(struct i2c_adapter *i2c,
> @@ -531,10 +535,9 @@ struct mii_bus *mdio_i2c_alloc(struct device *parent, struct i2c_adapter *i2c,
>  	case MDIO_I2C_ROLLBALL:
>  		ret = i2c_mii_init_rollball(i2c);
>  		if (ret < 0) {
> -			if (ret != -ENODEV)
> -				dev_err(parent,
> -					"Cannot initialize RollBall MDIO I2C protocol: %d\n",
> -					ret);
> +			dev_err(parent,
> +				"Cannot initialize RollBall MDIO I2C protocol: %d\n",
> +				ret);
>  			mdiobus_free(mii);
>  			return ERR_PTR(ret);
>  		}
> diff --git a/drivers/net/phy/sfp.c b/drivers/net/phy/sfp.c
> index c4d274ab651e..bbfaa0450798 100644
> --- a/drivers/net/phy/sfp.c
> +++ b/drivers/net/phy/sfp.c
> @@ -2174,17 +2174,10 @@ static void sfp_sm_fault(struct sfp *sfp, unsigned int next_state, bool warn)
>  
>  static int sfp_sm_add_mdio_bus(struct sfp *sfp)
>  {
> -	int ret;
> -
>  	if (sfp->mdio_protocol == MDIO_I2C_NONE)
>  		return 0;
>  
> -	ret = sfp_i2c_mdiobus_create(sfp);
> -	if (ret == -ENODEV) {
> -		sfp->mdio_protocol = MDIO_I2C_NONE;
> -		return 0;
> -	}
> -	return ret;
> +	return sfp_i2c_mdiobus_create(sfp);
>  }
>  
>  /* Probe a SFP for a PHY device if the module supports copper - the PHY
> @@ -2215,7 +2208,18 @@ static int sfp_sm_probe_for_phy(struct sfp *sfp)
>  		break;
>  
>  	case MDIO_I2C_ROLLBALL:
> -		err = sfp_sm_probe_phy(sfp, SFP_PHY_ADDR_ROLLBALL, true);
> +		/* Probe here, after module initialization delays, so that
> +		 * genuine RollBall bridges have had time to start up.
> +		 * Modules without a bridge (e.g. RTL8261BE) return -ENODEV.
> +		 */
> +		err = mdio_i2c_probe_rollball(sfp->i2c);
> +		if (err == -ENODEV) {
> +			sfp_i2c_mdiobus_destroy(sfp);
> +			sfp->mdio_protocol = MDIO_I2C_NONE;
> +			break;
> +		}
> +		if (!err)
> +			err = sfp_sm_probe_phy(sfp, SFP_PHY_ADDR_ROLLBALL, true);
>  		break;
>  	}
>  
> diff --git a/include/linux/mdio/mdio-i2c.h b/include/linux/mdio/mdio-i2c.h
> index 65b550a6fc32..5cf14f45c94b 100644
> --- a/include/linux/mdio/mdio-i2c.h
> +++ b/include/linux/mdio/mdio-i2c.h
> @@ -20,5 +20,6 @@ enum mdio_i2c_proto {
>  
>  struct mii_bus *mdio_i2c_alloc(struct device *parent, struct i2c_adapter *i2c,
>  			       enum mdio_i2c_proto protocol);
> +int mdio_i2c_probe_rollball(struct i2c_adapter *i2c);
>  
>  #endif

Re: [PATCH net-next v3 0/2] net: phy: sfp/mdio-i2c: defer RollBall probe + fix mii_bus leak

[Maxime Chevallier]

Hi Petr,

On 6/23/26 10:05, Petr Wozniak wrote:
> This series resends the RollBall bridge probe deferral (a fix for the
> regression in commit 8fe125892f40) and adds a related mii_bus leak fix.

These are bugfixes, you need to target the 'net' tree as explained here :

https://docs.kernel.org/process/maintainer-netdev.html

Thanks :)

Maxime
> 
> Patch 1 fixes a pre-existing mii_bus leak in sfp_i2c_mdiobus_destroy()
> that has been present since the helper was introduced in 2022. Patch 2's
> new -ENODEV path destroys the MDIO bus via sfp_i2c_mdiobus_destroy(), so
> patch 1 is a prerequisite to avoid leaking the bus on that path.
> 
> The v2 deferral patch was corrupted in transit and failed to apply; it is
> regenerated here against current net-next with no functional change.
> 
> v3:
>  - Resend: v2 defer patch was corrupted in transit and failed to apply
>    (netdev/apply); regenerated against current net-next.
>  - Fixed block comment style flagged by checkpatch. No functional change.
>  - Added patch 1/2 (sfp: free mii_bus in sfp_i2c_mdiobus_destroy).
> v2 (defer):
>  - Generalized scope: regression affects boot-inserted and hotplugged
>    modules where bridge init exceeds 200 ms; Aleksander Bajkowski
>    confirmed FLYPRO SFP-10GT-CS-30M / AQR113C broken when hotplugged.
>  - Corrected state machine description (probe runs in SFP_S_INIT after
>    SFP_S_WAIT) - Jan Hoffmann.
>  - No code changes from v1.
> v1: initial submission.
> 
> Petr Wozniak (2):
>   net: phy: sfp: free mii_bus in sfp_i2c_mdiobus_destroy
>   net: phy: mdio-i2c: defer RollBall bridge probe to PHY discovery
> 
>  drivers/net/mdio/mdio-i2c.c   | 15 +++++++++------
>  drivers/net/phy/sfp.c         | 23 ++++++++++++++---------
>  include/linux/mdio/mdio-i2c.h |  1 +
>  3 files changed, 24 insertions(+), 15 deletions(-)
> 
> 
> base-commit: b85966adbf5de0668a815c6e3527f87e0c387fb4