Patchwork i2c-scmi: remove some bogus NULL checks

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Submitter Dan Carpenter
Date Oct. 19, 2013, 8:46 a.m.
Message ID <20131019084622.GA9312@longonot.mountain>
Download mbox | patch
Permalink /patch/284857/
State Accepted
Headers show

Comments

Dan Carpenter - Oct. 19, 2013, 8:46 a.m.
"obj" can't be NULL here.

We already know that "pkg->package.elements" gives us a valid pointer
so the next pointer after that is also non-NULL.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

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Wolfram Sang - Oct. 30, 2013, 4:02 p.m.
On Sat, Oct 19, 2013 at 11:46:22AM +0300, Dan Carpenter wrote:
> "obj" can't be NULL here.
> 
> We already know that "pkg->package.elements" gives us a valid pointer
> so the next pointer after that is also non-NULL.

Why is that? Can't see it...

> 
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> 
> diff --git a/drivers/i2c/busses/i2c-scmi.c b/drivers/i2c/busses/i2c-scmi.c
> index c447e8d..5992355 100644
> --- a/drivers/i2c/busses/i2c-scmi.c
> +++ b/drivers/i2c/busses/i2c-scmi.c
> @@ -223,7 +223,7 @@ acpi_smbus_cmi_access(struct i2c_adapter *adap, u16 addr, unsigned short flags,
>  		goto out;
>  
>  	obj = pkg->package.elements + 1;
> -	if (obj == NULL || obj->type != ACPI_TYPE_INTEGER) {
> +	if (obj->type != ACPI_TYPE_INTEGER) {
>  		ACPI_ERROR((AE_INFO, "Invalid argument type"));
>  		result = -EIO;
>  		goto out;
> @@ -235,7 +235,7 @@ acpi_smbus_cmi_access(struct i2c_adapter *adap, u16 addr, unsigned short flags,
>  	case I2C_SMBUS_BYTE:
>  	case I2C_SMBUS_BYTE_DATA:
>  	case I2C_SMBUS_WORD_DATA:
> -		if (obj == NULL || obj->type != ACPI_TYPE_INTEGER) {
> +		if (obj->type != ACPI_TYPE_INTEGER) {
>  			ACPI_ERROR((AE_INFO, "Invalid argument type"));
>  			result = -EIO;
>  			goto out;
> @@ -246,7 +246,7 @@ acpi_smbus_cmi_access(struct i2c_adapter *adap, u16 addr, unsigned short flags,
>  			data->byte = obj->integer.value;
>  		break;
>  	case I2C_SMBUS_BLOCK_DATA:
> -		if (obj == NULL || obj->type != ACPI_TYPE_BUFFER) {
> +		if (obj->type != ACPI_TYPE_BUFFER) {
>  			ACPI_ERROR((AE_INFO, "Invalid argument type"));
>  			result = -EIO;
>  			goto out;
Dan Carpenter - Oct. 30, 2013, 4:39 p.m.
On Wed, Oct 30, 2013 at 05:02:58PM +0100, Wolfram Sang wrote:
> > --- a/drivers/i2c/busses/i2c-scmi.c
> > +++ b/drivers/i2c/busses/i2c-scmi.c
> > @@ -223,7 +223,7 @@ acpi_smbus_cmi_access(struct i2c_adapter *adap, u16 addr, unsigned short flags,
> >  		goto out;
> >  
> >  	obj = pkg->package.elements + 1;
> > -	if (obj == NULL || obj->type != ACPI_TYPE_INTEGER) {
> > +	if (obj->type != ACPI_TYPE_INTEGER) {
> >  		ACPI_ERROR((AE_INFO, "Invalid argument type"));
> >  		result = -EIO;
> >  		goto out;

For obj to be 0 then pkg->package.elements must be -1.  If we're getting
a pointer of -1 then we're already screwed.  Also we already used
pkg->elements without the "+ 1" so we know that's not -1.

The reason for this patch was that some compilers assume pointer math
can't overflow and my checker was complaining.  We use
-fno-strict-overflow in the kernel, but it still seemed worth cleaning.

regards,
dan carpenter

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Wolfram Sang - Oct. 31, 2013, 11:57 a.m.
On Sat, Oct 19, 2013 at 11:46:22AM +0300, Dan Carpenter wrote:
> "obj" can't be NULL here.
> 
> We already know that "pkg->package.elements" gives us a valid pointer
> so the next pointer after that is also non-NULL.
> 
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

Applied to for-next, thanks!

Patch

diff --git a/drivers/i2c/busses/i2c-scmi.c b/drivers/i2c/busses/i2c-scmi.c
index c447e8d..5992355 100644
--- a/drivers/i2c/busses/i2c-scmi.c
+++ b/drivers/i2c/busses/i2c-scmi.c
@@ -223,7 +223,7 @@  acpi_smbus_cmi_access(struct i2c_adapter *adap, u16 addr, unsigned short flags,
 		goto out;
 
 	obj = pkg->package.elements + 1;
-	if (obj == NULL || obj->type != ACPI_TYPE_INTEGER) {
+	if (obj->type != ACPI_TYPE_INTEGER) {
 		ACPI_ERROR((AE_INFO, "Invalid argument type"));
 		result = -EIO;
 		goto out;
@@ -235,7 +235,7 @@  acpi_smbus_cmi_access(struct i2c_adapter *adap, u16 addr, unsigned short flags,
 	case I2C_SMBUS_BYTE:
 	case I2C_SMBUS_BYTE_DATA:
 	case I2C_SMBUS_WORD_DATA:
-		if (obj == NULL || obj->type != ACPI_TYPE_INTEGER) {
+		if (obj->type != ACPI_TYPE_INTEGER) {
 			ACPI_ERROR((AE_INFO, "Invalid argument type"));
 			result = -EIO;
 			goto out;
@@ -246,7 +246,7 @@  acpi_smbus_cmi_access(struct i2c_adapter *adap, u16 addr, unsigned short flags,
 			data->byte = obj->integer.value;
 		break;
 	case I2C_SMBUS_BLOCK_DATA:
-		if (obj == NULL || obj->type != ACPI_TYPE_BUFFER) {
+		if (obj->type != ACPI_TYPE_BUFFER) {
 			ACPI_ERROR((AE_INFO, "Invalid argument type"));
 			result = -EIO;
 			goto out;