staging: comedi: have comedi_set_spriv() allocate the memory

As suggested by Ian Abbott, comedi_set_spriv() can only be used to
set the subdevice->private pointer to something that can be kfree()'d.
Rename the function to comedi_alloc_spriv() and have it kzalloc() the
memory as well as set the private pointer. This saves a function call
in the drivers and avoids the possibility of incorrectly calling
comedi_set_spriv() for some pointer that is not meant to be kfree()'d.
Signed-off-by: NH Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: NIan Abbott <abbotti@mev.co.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/comedi_fops.c

@@ -532,19 +532,21 @@ static bool comedi_is_subdevice_idle(struct comedi_subdevice *s)
 }
 
 /**
- * comedi_set_spriv() - Set the subdevice private data pointer.
+ * comedi_alloc_spriv() - Allocate memory for the subdevice private data.
  * @s: comedi_subdevice struct
- * @data: pointer to the private data
+ * @size: size of the memory to allocate
  *
  * This also sets the subdevice runflags to allow the core to automatically
  * free the private data during the detach.
  */
-void comedi_set_spriv(struct comedi_subdevice *s, void *data)
+void *comedi_alloc_spriv(struct comedi_subdevice *s, size_t size)
 {
-	s->private = data;
+	s->private = kzalloc(size, GFP_KERNEL);
+	if (s->private)
 		comedi_set_subdevice_runflags(s, ~0, SRF_FREE_SPRIV);
+	return s->private;
 }
-EXPORT_SYMBOL_GPL(comedi_set_spriv);
+EXPORT_SYMBOL_GPL(comedi_alloc_spriv);
 
 /*
    This function restores a subdevice to an idle state.

drivers/staging/comedi/comedidev.h

@@ -270,7 +270,8 @@ enum subdevice_runflags {
 };
 
 bool comedi_is_subdevice_running(struct comedi_subdevice *s);
-void comedi_set_spriv(struct comedi_subdevice *s, void *data);
+
+void *comedi_alloc_spriv(struct comedi_subdevice *s, size_t size);
 
 int comedi_check_chanlist(struct comedi_subdevice *s,
 			  int n,

drivers/staging/comedi/drivers/8255.c

@@ -76,7 +76,6 @@ I/O port base address can be found in the output of 'lspci -v'.
 #include "../comedidev.h"
 
 #include <linux/ioport.h>
-#include <linux/slab.h>
 
 #include "comedi_fc.h"
 #include "8255.h"
@@ -285,10 +284,9 @@ int subdev_8255_init(struct comedi_device *dev, struct comedi_subdevice *s,
 {
 	struct subdev_8255_private *spriv;
 
-	spriv = kzalloc(sizeof(*spriv), GFP_KERNEL);
+	spriv = comedi_alloc_spriv(s, sizeof(*spriv));
 	if (!spriv)
 		return -ENOMEM;
-	comedi_set_spriv(s, spriv);
 
 	spriv->iobase	= iobase;
 	spriv->io	= io ? io : subdev_8255_io;

drivers/staging/comedi/drivers/addi_watchdog.c

@@ -126,10 +126,9 @@ int addi_watchdog_init(struct comedi_subdevice *s, unsigned long iobase)
 {
 	struct addi_watchdog_private *spriv;
 
-	spriv = kzalloc(sizeof(*spriv), GFP_KERNEL);
+	spriv = comedi_alloc_spriv(s, sizeof(*spriv));
 	if (!spriv)
 		return -ENOMEM;
-	comedi_set_spriv(s, spriv);
 
 	spriv->iobase = iobase;
 

drivers/staging/comedi/drivers/amplc_dio200_common.c

@@ -556,10 +556,9 @@ dio200_subdev_intr_init(struct comedi_device *dev, struct comedi_subdevice *s,
 	const struct dio200_layout *layout = dio200_dev_layout(dev);
 	struct dio200_subdev_intr *subpriv;
 
-	subpriv = kzalloc(sizeof(*subpriv), GFP_KERNEL);
+	subpriv = comedi_alloc_spriv(s, sizeof(*subpriv));
 	if (!subpriv)
 		return -ENOMEM;
-	comedi_set_spriv(s, subpriv);
 
 	subpriv->ofs = offset;
 	subpriv->valid_isns = valid_isns;
@@ -883,10 +882,9 @@ dio200_subdev_8254_init(struct comedi_device *dev, struct comedi_subdevice *s,
 	struct dio200_subdev_8254 *subpriv;
 	unsigned int chan;
 
-	subpriv = kzalloc(sizeof(*subpriv), GFP_KERNEL);
+	subpriv = comedi_alloc_spriv(s, sizeof(*subpriv));
 	if (!subpriv)
 		return -ENOMEM;
-	comedi_set_spriv(s, subpriv);
 
 	s->type = COMEDI_SUBD_COUNTER;
 	s->subdev_flags = SDF_WRITABLE | SDF_READABLE;
@@ -1019,10 +1017,9 @@ static int dio200_subdev_8255_init(struct comedi_device *dev,
 {
 	struct dio200_subdev_8255 *subpriv;
 
-	subpriv = kzalloc(sizeof(*subpriv), GFP_KERNEL);
+	subpriv = comedi_alloc_spriv(s, sizeof(*subpriv));
 	if (!subpriv)
 		return -ENOMEM;
-	comedi_set_spriv(s, subpriv);
 
 	subpriv->ofs = offset;
 

drivers/staging/comedi/drivers/ni_65xx.c

@@ -281,18 +281,6 @@ static inline struct ni_65xx_subdevice_private *sprivate(struct comedi_subdevice
 	return subdev->private;
 }
 
-static int ni_65xx_alloc_subdevice_private(struct comedi_subdevice *s)
-{
-	struct ni_65xx_subdevice_private *spriv;
-
-	spriv = kzalloc(sizeof(*spriv), GFP_KERNEL);
-	if (!spriv)
-		return -ENOMEM;
-	comedi_set_spriv(s, spriv);
-
-	return 0;
-}
-
 static int ni_65xx_config_filter(struct comedi_device *dev,
 				 struct comedi_subdevice *s,
 				 struct comedi_insn *insn, unsigned int *data)
@@ -587,6 +575,7 @@ static int ni_65xx_auto_attach(struct comedi_device *dev,
 	struct pci_dev *pcidev = comedi_to_pci_dev(dev);
 	const struct ni_65xx_board *board = NULL;
 	struct ni_65xx_private *devpriv;
+	struct ni_65xx_subdevice_private *spriv;
 	struct comedi_subdevice *s;
 	unsigned i;
 	int ret;
@@ -635,10 +624,10 @@ static int ni_65xx_auto_attach(struct comedi_device *dev,
 		s->maxdata = 1;
 		s->insn_config = ni_65xx_dio_insn_config;
 		s->insn_bits = ni_65xx_dio_insn_bits;
-		ret = ni_65xx_alloc_subdevice_private(s);
-		if (ret)
-			return ret;
-		sprivate(s)->base_port = 0;
+		spriv = comedi_alloc_spriv(s, sizeof(*spriv));
+		if (!spriv)
+			return -ENOMEM;
+		spriv->base_port = 0;
 	} else {
 		s->type = COMEDI_SUBD_UNUSED;
 	}
@@ -652,10 +641,10 @@ static int ni_65xx_auto_attach(struct comedi_device *dev,
 		s->range_table = &range_digital;
 		s->maxdata = 1;
 		s->insn_bits = ni_65xx_dio_insn_bits;
-		ret = ni_65xx_alloc_subdevice_private(s);
-		if (ret)
-			return ret;
-		sprivate(s)->base_port = board->num_di_ports;
+		spriv = comedi_alloc_spriv(s, sizeof(*spriv));
+		if (!spriv)
+			return -ENOMEM;
+		spriv->base_port = board->num_di_ports;
 	} else {
 		s->type = COMEDI_SUBD_UNUSED;
 	}
@@ -670,10 +659,10 @@ static int ni_65xx_auto_attach(struct comedi_device *dev,
 		s->maxdata = 1;
 		s->insn_config = ni_65xx_dio_insn_config;
 		s->insn_bits = ni_65xx_dio_insn_bits;
-		ret = ni_65xx_alloc_subdevice_private(s);
-		if (ret)
-			return ret;
-		sprivate(s)->base_port = 0;
+		spriv = comedi_alloc_spriv(s, sizeof(*spriv));
+		if (!spriv)
+			return -ENOMEM;
+		spriv->base_port = 0;
 		for (i = 0; i < board->num_dio_ports; ++i) {
 			/*  configure all ports for input */
 			writeb(0x1,