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drivers: pmbus: core: Prevent calling pmbus_set_page with negative page

prefix=PATCH Eddie James 2 participants 4 messages Oct 25, 2017 Hardware monitoring

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Eddie James

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#0 lore raw

From: "Edward A. James" <[email protected]>

For devices with word data registers, the pmbus core may call read/write word data functions with a page value of -1, in order to perform the operation without setting the page. However, the read/write word data functions accept only unsigned 8-bit page numbers, resulting in setting a page of 0xFF in this situation. This may result in errors or undefined behavior of some devices (specifically the ir35221, which allows the page to be set to 0xFF, but some subsequent operations to read registers may fail).

Signed-off-by Edward A. James <[email protected]>
---
 drivers/hwmon/pmbus/pmbus.h      |  4 ++--
 drivers/hwmon/pmbus/pmbus_core.c | 29 ++++++++++++++++++-----------
 2 files changed, 20 insertions(+), 13 deletions(-)
drivers/hwmon/pmbus/pmbus.h +2 -2
index 4efa2bd..4a16da6 100644
@@ -405,8 +405,8 @@ struct pmbus_driver_info {
 
 void pmbus_clear_cache(struct i2c_client *client);
 int pmbus_set_page(struct i2c_client *client, u8 page);
-int pmbus_read_word_data(struct i2c_client *client, u8 page, u8 reg);
-int pmbus_write_word_data(struct i2c_client *client, u8 page, u8 reg, u16 word);
+int pmbus_read_word_data(struct i2c_client *client, int page, u8 reg);
+int pmbus_write_word_data(struct i2c_client *client, int page, u8 reg, u16 word);
 int pmbus_read_byte_data(struct i2c_client *client, int page, u8 reg);
 int pmbus_write_byte(struct i2c_client *client, int page, u8 value);
 int pmbus_write_byte_data(struct i2c_client *client, int page, u8 reg,
drivers/hwmon/pmbus/pmbus_core.c +18 -11
index 302f0ae..6d6e030 100644
@@ -186,13 +186,16 @@ static int _pmbus_write_byte(struct i2c_client *client, int page, u8 value)
 	return pmbus_write_byte(client, page, value);
 }
 
-int pmbus_write_word_data(struct i2c_client *client, u8 page, u8 reg, u16 word)
+int pmbus_write_word_data(struct i2c_client *client, int page, u8 reg,
+			  u16 word)
 {
 	int rv;
 
-	rv = pmbus_set_page(client, page);
-	if (rv < 0)
-		return rv;
+	if (page >= 0) {
+		rv = pmbus_set_page(client, page);
+		if (rv < 0)
+			return rv;
+	}
 
 	return i2c_smbus_write_word_data(client, reg, word);
 }

@@ -219,13 +222,15 @@ static int _pmbus_write_word_data(struct i2c_client *client, int page, int reg,
 	return pmbus_write_word_data(client, page, reg, word);
 }
 
-int pmbus_read_word_data(struct i2c_client *client, u8 page, u8 reg)
+int pmbus_read_word_data(struct i2c_client *client, int page, u8 reg)
 {
 	int rv;
 
-	rv = pmbus_set_page(client, page);
-	if (rv < 0)
-		return rv;
+	if (page >= 0) {
+		rv = pmbus_set_page(client, page);
+		if (rv < 0)
+			return rv;
+	}
 
 	return i2c_smbus_read_word_data(client, reg);
 }

@@ -269,9 +274,11 @@ int pmbus_write_byte_data(struct i2c_client *client, int page, u8 reg, u8 value)
 {
 	int rv;
 
-	rv = pmbus_set_page(client, page);
-	if (rv < 0)
-		return rv;
+	if (page >= 0) {
+		rv = pmbus_set_page(client, page);
+		if (rv < 0)
+			return rv;
+	}
 
 	return i2c_smbus_write_byte_data(client, reg, value);
 }
Signature · 1 line
1.8.3.1
maintainer
#1 lore raw
Quoted 11 lines · Eddie James

From: "Edward A. James" <[email protected]>

For devices with word data registers, the pmbus core may call read/write word data functions with a page value of -1, in order to perform the operation without setting the page. However, the read/write word data functions accept only unsigned 8-bit page numbers, resulting in setting a page of 0xFF in this situation. This may result in errors or undefined behavior of some devices (specifically the ir35221, which allows the page to be set to 0xFF, but some subsequent operations to read registers may fail).

Good catch.

Subject came off a bit odd.

[prefix=PATCH] drivers: pmbus: core: Prevent ...

Please use "[PATCH] hwmon: (pmbus/core) Prevent ..."

This me wonder if we should move the check into pmbus_set_page() instead.

int pmbus_set_page(struct i2c_client *client, int page)

{
	...
	if (page >= 0 && page != data->currpage) {
	...
}

What do you think ?

Thanks,
Guenter

Quoted 84 lines
Signed-off-by Edward A. James <[email protected]>
---
 drivers/hwmon/pmbus/pmbus.h      |  4 ++--
 drivers/hwmon/pmbus/pmbus_core.c | 29 ++++++++++++++++++-----------
 2 files changed, 20 insertions(+), 13 deletions(-)
drivers/hwmon/pmbus/pmbus.h +2 -2
index 4efa2bd..4a16da6 100644
@@ -405,8 +405,8 @@ struct pmbus_driver_info {
 
 void pmbus_clear_cache(struct i2c_client *client);
 int pmbus_set_page(struct i2c_client *client, u8 page);
-int pmbus_read_word_data(struct i2c_client *client, u8 page, u8 reg);
-int pmbus_write_word_data(struct i2c_client *client, u8 page, u8 reg, u16 word);
+int pmbus_read_word_data(struct i2c_client *client, int page, u8 reg);
+int pmbus_write_word_data(struct i2c_client *client, int page, u8 reg, u16 word);
 int pmbus_read_byte_data(struct i2c_client *client, int page, u8 reg);
 int pmbus_write_byte(struct i2c_client *client, int page, u8 value);
 int pmbus_write_byte_data(struct i2c_client *client, int page, u8 reg,
drivers/hwmon/pmbus/pmbus_core.c +18 -11
index 302f0ae..6d6e030 100644
@@ -186,13 +186,16 @@ static int _pmbus_write_byte(struct i2c_client *client, int page, u8 value)
 	return pmbus_write_byte(client, page, value);
 }
 
-int pmbus_write_word_data(struct i2c_client *client, u8 page, u8 reg, u16 word)
+int pmbus_write_word_data(struct i2c_client *client, int page, u8 reg,
+			  u16 word)
 {
 	int rv;
 
-	rv = pmbus_set_page(client, page);
-	if (rv < 0)
-		return rv;
+	if (page >= 0) {
+		rv = pmbus_set_page(client, page);
+		if (rv < 0)
+			return rv;
+	}
 
 	return i2c_smbus_write_word_data(client, reg, word);
 }

@@ -219,13 +222,15 @@ static int _pmbus_write_word_data(struct i2c_client *client, int page, int reg,
 	return pmbus_write_word_data(client, page, reg, word);
 }
 
-int pmbus_read_word_data(struct i2c_client *client, u8 page, u8 reg)
+int pmbus_read_word_data(struct i2c_client *client, int page, u8 reg)
 {
 	int rv;
 
-	rv = pmbus_set_page(client, page);
-	if (rv < 0)
-		return rv;
+	if (page >= 0) {
+		rv = pmbus_set_page(client, page);
+		if (rv < 0)
+			return rv;
+	}
 
 	return i2c_smbus_read_word_data(client, reg);
 }

@@ -269,9 +274,11 @@ int pmbus_write_byte_data(struct i2c_client *client, int page, u8 reg, u8 value)
 {
 	int rv;
 
-	rv = pmbus_set_page(client, page);
-	if (rv < 0)
-		return rv;
+	if (page >= 0) {
+		rv = pmbus_set_page(client, page);
+		if (rv < 0)
+			return rv;
+	}
 
 	return i2c_smbus_write_byte_data(client, reg, value);
 }
Signature · 1 line
1.8.3.1
author
#2 lore raw
Quoted 12 lines · Guenter Roeck
Quoted 11 lines · Eddie James

From: "Edward A. James" <[email protected]>

For devices with word data registers, the pmbus core may call read/write word data functions with a page value of -1, in order to perform the operation without setting the page. However, the read/write word data functions accept only unsigned 8-bit page numbers, resulting in setting a page of 0xFF in this situation. This may result in errors or undefined behavior of some devices (specifically the ir35221, which allows the page to be set to 0xFF, but some subsequent operations to read registers may fail).

Quoted 7 lines

Good catch.

Subject came off a bit odd.

[prefix=PATCH] drivers: pmbus: core: Prevent ...

Please use "[PATCH] hwmon: (pmbus/core) Prevent ..."

Yea I hit = instead of - in "--subject-prefix"...

Quoted 4 lines

This me wonder if we should move the check into pmbus_set_page() instead.

Quoted 8 lines

int pmbus_set_page(struct i2c_client *client, int page)

{
	...
	if (page >= 0 && page != data->currpage) {
	...
}

What do you think ?

Yea that works well too, and reduces the code size. Though I suppose it makes the interface slightly less intuitive, as someone might think they can pass a value larger than u8. At least for the read/write functions, a negative value has a meaning - "don't change the page."

Up to you, either way. I'm happy to change it.

Thanks,
Eddie

Quoted 88 lines

Thanks,
Guenter

Quoted 84 lines
Signed-off-by Edward A. James <[email protected]>
---
  drivers/hwmon/pmbus/pmbus.h      |  4 ++--
  drivers/hwmon/pmbus/pmbus_core.c | 29 ++++++++++++++++++-----------
  2 files changed, 20 insertions(+), 13 deletions(-)
drivers/hwmon/pmbus/pmbus.h +2 -2
index 4efa2bd..4a16da6 100644
@@ -405,8 +405,8 @@ struct pmbus_driver_info {
 
  void pmbus_clear_cache(struct i2c_client *client);
  int pmbus_set_page(struct i2c_client *client, u8 page);
-int pmbus_read_word_data(struct i2c_client *client, u8 page, u8 reg);
-int pmbus_write_word_data(struct i2c_client *client, u8 page, u8 reg, u16 word);
+int pmbus_read_word_data(struct i2c_client *client, int page, u8 reg);
+int pmbus_write_word_data(struct i2c_client *client, int page, u8 reg, u16 word);
  int pmbus_read_byte_data(struct i2c_client *client, int page, u8 reg);
  int pmbus_write_byte(struct i2c_client *client, int page, u8 value);
  int pmbus_write_byte_data(struct i2c_client *client, int page, u8 reg,
drivers/hwmon/pmbus/pmbus_core.c +18 -11
index 302f0ae..6d6e030 100644
@@ -186,13 +186,16 @@ static int _pmbus_write_byte(struct i2c_client *client, int page, u8 value)
  	return pmbus_write_byte(client, page, value);
  }
 
-int pmbus_write_word_data(struct i2c_client *client, u8 page, u8 reg, u16 word)
+int pmbus_write_word_data(struct i2c_client *client, int page, u8 reg,
+			  u16 word)
  {
  	int rv;
 
-	rv = pmbus_set_page(client, page);
-	if (rv < 0)
-		return rv;
+	if (page >= 0) {
+		rv = pmbus_set_page(client, page);
+		if (rv < 0)
+			return rv;
+	}
 
  	return i2c_smbus_write_word_data(client, reg, word);
  }

@@ -219,13 +222,15 @@ static int _pmbus_write_word_data(struct i2c_client *client, int page, int reg,
  	return pmbus_write_word_data(client, page, reg, word);
  }
 
-int pmbus_read_word_data(struct i2c_client *client, u8 page, u8 reg)
+int pmbus_read_word_data(struct i2c_client *client, int page, u8 reg)
  {
  	int rv;
 
-	rv = pmbus_set_page(client, page);
-	if (rv < 0)
-		return rv;
+	if (page >= 0) {
+		rv = pmbus_set_page(client, page);
+		if (rv < 0)
+			return rv;
+	}
 
  	return i2c_smbus_read_word_data(client, reg);
  }

@@ -269,9 +274,11 @@ int pmbus_write_byte_data(struct i2c_client *client, int page, u8 reg, u8 value)
  {
  	int rv;
 
-	rv = pmbus_set_page(client, page);
-	if (rv < 0)
-		return rv;
+	if (page >= 0) {
+		rv = pmbus_set_page(client, page);
+		if (rv < 0)
+			return rv;
+	}
 
  	return i2c_smbus_write_byte_data(client, reg, value);
  }
Signature · 1 line
1.8.3.1
maintainer
#3 lore raw
Quoted 36 lines · Eddie James
Quoted 12 lines · Guenter Roeck
Quoted 11 lines · Eddie James

From: "Edward A. James" <[email protected]>

For devices with word data registers, the pmbus core may call read/write word data functions with a page value of -1, in order to perform the operation without setting the page. However, the read/write word data functions accept only unsigned 8-bit page numbers, resulting in setting a page of 0xFF in this situation. This may result in errors or undefined behavior of some devices (specifically the ir35221, which allows the page to be set to 0xFF, but some subsequent operations to read registers may fail).

Quoted 7 lines

Good catch.

Subject came off a bit odd.

[prefix=PATCH] drivers: pmbus: core: Prevent ...

Please use "[PATCH] hwmon: (pmbus/core) Prevent ..."

Yea I hit = instead of - in "--subject-prefix"...

Quoted 11 lines

This me wonder if we should move the check into pmbus_set_page() instead.

int pmbus_set_page(struct i2c_client *client, int page)

{
	...
	if (page >= 0 && page != data->currpage) {
	...
}
Quoted 9 lines
Quoted 1 line

What do you think ?

Yea that works well too, and reduces the code size. Though I suppose it makes the interface slightly less intuitive, as someone might think they can pass a value larger than u8. At least for the read/write functions, a negative value has a meaning - "don't change the page."

Up to you, either way. I'm happy to change it.

Let's do it.

Thanks,
Guenter

Quoted 83 lines

Thanks,
Eddie

Quoted 79 lines

Thanks,
Guenter

Quoted 75 lines
Signed-off-by Edward A. James <[email protected]>
---
 drivers/hwmon/pmbus/pmbus.h      |  4 ++--
 drivers/hwmon/pmbus/pmbus_core.c | 29 ++++++++++++++++++-----------
 2 files changed, 20 insertions(+), 13 deletions(-)
drivers/hwmon/pmbus/pmbus.h +2 -2
index 4efa2bd..4a16da6 100644
@@ -405,8 +405,8 @@ struct pmbus_driver_info {
 void pmbus_clear_cache(struct i2c_client *client);
 int pmbus_set_page(struct i2c_client *client, u8 page);
-int pmbus_read_word_data(struct i2c_client *client, u8 page, u8 reg);
-int pmbus_write_word_data(struct i2c_client *client, u8 page, u8 reg, u16 word);
+int pmbus_read_word_data(struct i2c_client *client, int page, u8 reg);
+int pmbus_write_word_data(struct i2c_client *client, int page, u8 reg, u16 word);
 int pmbus_read_byte_data(struct i2c_client *client, int page, u8 reg);
 int pmbus_write_byte(struct i2c_client *client, int page, u8 value);
 int pmbus_write_byte_data(struct i2c_client *client, int page, u8 reg,
drivers/hwmon/pmbus/pmbus_core.c +18 -11
index 302f0ae..6d6e030 100644
@@ -186,13 +186,16 @@ static int _pmbus_write_byte(struct i2c_client *client, int page, u8 value)
 	return pmbus_write_byte(client, page, value);
 }
-int pmbus_write_word_data(struct i2c_client *client, u8 page, u8 reg, u16 word)
+int pmbus_write_word_data(struct i2c_client *client, int page, u8 reg,
+			  u16 word)
 {
 	int rv;
-	rv = pmbus_set_page(client, page);
-	if (rv < 0)
-		return rv;
+	if (page >= 0) {
+		rv = pmbus_set_page(client, page);
+		if (rv < 0)
+			return rv;
+	}
 	return i2c_smbus_write_word_data(client, reg, word);
 }

@@ -219,13 +222,15 @@ static int _pmbus_write_word_data(struct i2c_client *client, int page, int reg,
 	return pmbus_write_word_data(client, page, reg, word);
 }
-int pmbus_read_word_data(struct i2c_client *client, u8 page, u8 reg)
+int pmbus_read_word_data(struct i2c_client *client, int page, u8 reg)
 {
 	int rv;
-	rv = pmbus_set_page(client, page);
-	if (rv < 0)
-		return rv;
+	if (page >= 0) {
+		rv = pmbus_set_page(client, page);
+		if (rv < 0)
+			return rv;
+	}
 	return i2c_smbus_read_word_data(client, reg);
 }

@@ -269,9 +274,11 @@ int pmbus_write_byte_data(struct i2c_client *client, int page, u8 reg, u8 value)
 {
 	int rv;
-	rv = pmbus_set_page(client, page);
-	if (rv < 0)
-		return rv;
+	if (page >= 0) {
+		rv = pmbus_set_page(client, page);
+		if (rv < 0)
+			return rv;
+	}
 	return i2c_smbus_write_byte_data(client, reg, value);
 }
Signature · 1 line
1.8.3.1