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[RFC] net: mdio_bus: make check in mdiobus_prevent_c45_scan more granular

Message ID c379276f-2276-4c15-b483-7379b16031f7@gmail.com (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series [RFC] net: mdio_bus: make check in mdiobus_prevent_c45_scan more granular | expand

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netdev/series_format warning Single patches do not need cover letters; Target tree name not specified in the subject
netdev/tree_selection success Guessed tree name to be net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1113 this patch: 1113
netdev/cc_maintainers warning 3 maintainers not CCed: edumazet@google.com kuba@kernel.org pabeni@redhat.com
netdev/build_clang success Errors and warnings before: 1140 this patch: 1140
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 1140 this patch: 1140
netdev/checkpatch warning WARNING: line length of 82 exceeds 80 columns
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Heiner Kallweit Jan. 2, 2024, 2:38 p.m. UTC
Matching on OUI level is a quite big hammer. So let's make matching
more granular.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
This is what I'm thinking of. Maybe the problem of misbehaving
on c45 access affects certain groups of PHY's only.
Then we don't have to blacklist all PHY's from this vendor.
What do you think?
---
 drivers/net/phy/mdio_bus.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

Comments

Russell King (Oracle) Jan. 2, 2024, 3:18 p.m. UTC | #1
On Tue, Jan 02, 2024 at 03:38:05PM +0100, Heiner Kallweit wrote:
> Matching on OUI level is a quite big hammer. So let's make matching
> more granular.
> 
> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
> ---
> This is what I'm thinking of. Maybe the problem of misbehaving
> on c45 access affects certain groups of PHY's only.
> Then we don't have to blacklist all PHY's from this vendor.
> What do you think?
> ---
>  drivers/net/phy/mdio_bus.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
> index 6cf73c156..848d5d2d6 100644
> --- a/drivers/net/phy/mdio_bus.c
> +++ b/drivers/net/phy/mdio_bus.c
> @@ -621,19 +621,27 @@ static int mdiobus_scan_bus_c45(struct mii_bus *bus)
>   */
>  static bool mdiobus_prevent_c45_scan(struct mii_bus *bus)
>  {
> -	int i;
> +	const struct {
> +		u32 phy_id;
> +		u32 phy_id_mask;
> +	} id_list[] = {
> +		{ MICREL_OUI << 10, GENMASK(31, 10) },
> +	};

Do we need a new structure? Would struct mdio_device_id do (which
actually has exactly the same members with exactly the same names in
exactly the same order.)

Also, as this is not static, the compiler will need to generate code
to initialise the structure, possibly storing a copy of it in the
.data segment and memcpy()ing it onto the kernel stack. I suggest
marking it static to avoid that unnecessary hidden code complexity.

> +		for (j = 0; j < ARRAY_SIZE(id_list); j++) {
> +			u32 mask = id_list[j].phy_id_mask;
> +
> +			if ((phydev->phy_id & mask) == (id_list[j].phy_id & mask))

			if (phy_id_compare(phydev->phy_id, id_list[j].phy_id,
					   id_list[j].phy_id_mask))

Or it could be:

			const struct mdio_device_id *id = id_list + j;

			if (phy_id_compare(phydev->phy_id, id->phy_id,
					   id->phy_id_mask))
Heiner Kallweit Jan. 2, 2024, 3:47 p.m. UTC | #2
On 02.01.2024 16:18, Russell King (Oracle) wrote:
> On Tue, Jan 02, 2024 at 03:38:05PM +0100, Heiner Kallweit wrote:
>> Matching on OUI level is a quite big hammer. So let's make matching
>> more granular.
>>
>> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
>> ---
>> This is what I'm thinking of. Maybe the problem of misbehaving
>> on c45 access affects certain groups of PHY's only.
>> Then we don't have to blacklist all PHY's from this vendor.
>> What do you think?
>> ---
>>  drivers/net/phy/mdio_bus.c | 18 +++++++++++++-----
>>  1 file changed, 13 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
>> index 6cf73c156..848d5d2d6 100644
>> --- a/drivers/net/phy/mdio_bus.c
>> +++ b/drivers/net/phy/mdio_bus.c
>> @@ -621,19 +621,27 @@ static int mdiobus_scan_bus_c45(struct mii_bus *bus)
>>   */
>>  static bool mdiobus_prevent_c45_scan(struct mii_bus *bus)
>>  {
>> -	int i;
>> +	const struct {
>> +		u32 phy_id;
>> +		u32 phy_id_mask;
>> +	} id_list[] = {
>> +		{ MICREL_OUI << 10, GENMASK(31, 10) },
>> +	};
> 
> Do we need a new structure? Would struct mdio_device_id do (which
> actually has exactly the same members with exactly the same names in
> exactly the same order.)
> 
> Also, as this is not static, the compiler will need to generate code
> to initialise the structure, possibly storing a copy of it in the
> .data segment and memcpy()ing it onto the kernel stack. I suggest
> marking it static to avoid that unnecessary hidden code complexity.
> 
Both good points. I missed the static declaration.

>> +		for (j = 0; j < ARRAY_SIZE(id_list); j++) {
>> +			u32 mask = id_list[j].phy_id_mask;
>> +
>> +			if ((phydev->phy_id & mask) == (id_list[j].phy_id & mask))
> 
> 			if (phy_id_compare(phydev->phy_id, id_list[j].phy_id,
> 					   id_list[j].phy_id_mask))
> 
> Or it could be:
> 
> 			const struct mdio_device_id *id = id_list + j;
> 
> 			if (phy_id_compare(phydev->phy_id, id->phy_id,
> 					   id->phy_id_mask))
> 
This looks best to me.
diff mbox series

Patch

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 6cf73c156..848d5d2d6 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -621,19 +621,27 @@  static int mdiobus_scan_bus_c45(struct mii_bus *bus)
  */
 static bool mdiobus_prevent_c45_scan(struct mii_bus *bus)
 {
-	int i;
+	const struct {
+		u32 phy_id;
+		u32 phy_id_mask;
+	} id_list[] = {
+		{ MICREL_OUI << 10, GENMASK(31, 10) },
+	};
+	int i, j;
 
 	for (i = 0; i < PHY_MAX_ADDR; i++) {
 		struct phy_device *phydev;
-		u32 oui;
 
 		phydev = mdiobus_get_phy(bus, i);
 		if (!phydev)
 			continue;
-		oui = phydev->phy_id >> 10;
 
-		if (oui == MICREL_OUI)
-			return true;
+		for (j = 0; j < ARRAY_SIZE(id_list); j++) {
+			u32 mask = id_list[j].phy_id_mask;
+
+			if ((phydev->phy_id & mask) == (id_list[j].phy_id & mask))
+				return true;
+		}
 	}
 	return false;
 }