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Commit eb96c7fc authored by H Hartley Sweeten's avatar H Hartley Sweeten Committed by Greg Kroah-Hartman
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staging: comedi: adl_pci9118: tidy up pci9118_ai_setup_dma() 



For aesthetics, init the dmalen[01] local variables when they are declared.

Use a local variable, 'scan_bytes', for the (devpriv->ai_n_realscanlen << 1)
calculation. For aesthetics and clarification, use comedi_bytes_per_sample()
instead of the '<< 1' shift to calculate the value.

The local variable 'i' is badly named. Remove it and use a local variable
'tmp' where it is used.

When checking the DMA buffer lengths for non-neverending commands the
scan length calculation, (devpriv->ai_n_realscanlen << 1) * cmd->stop_arg,
could overflow. Use and unsigned long long local variable to hold the
calculation and avoid the overflow.

Signed-off-by: default avatarH Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: default avatarIan Abbott <abbotti@mev.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 45037a95

drivers/staging/comedi/drivers/adl_pci9118.c

+31 −36
Original line number Diff line number Diff line
@@ -801,10 +801,11 @@ static int pci9118_ai_setup_dma(struct comedi_device *dev, 
	struct comedi_cmd *cmd = &s->async->cmd;

	struct pci9118_dmabuf *dmabuf0 = &devpriv->dmabuf[0];

	struct pci9118_dmabuf *dmabuf1 = &devpriv->dmabuf[1];

	unsigned int dmalen0, dmalen1, i;

	unsigned int dmalen0 = dmabuf0->size;

	unsigned int dmalen1 = dmabuf1->size;

	unsigned int scan_bytes = devpriv->ai_n_realscanlen *

				  comedi_bytes_per_sample(s);



	dmalen0 = dmabuf0->size;

	dmalen1 = dmabuf1->size;

	/* isn't output buff smaller that our DMA buff? */

	if (dmalen0 > s->async->prealloc_bufsz) {

		/* align to 32bit down */
@@ -817,15 +818,15 @@ static int pci9118_ai_setup_dma(struct comedi_device *dev, 


	/* we want wake up every scan? */

	if (devpriv->ai_flags & CMDF_WAKE_EOS) {

		if (dmalen0 < (devpriv->ai_n_realscanlen << 1)) {

		if (dmalen0 < scan_bytes) {

			/* uff, too short DMA buffer, disable EOS support! */

			devpriv->ai_flags &= (~CMDF_WAKE_EOS);

			dev_info(dev->class_dev,

				 "WAR: DMA0 buf too short, can't support CMDF_WAKE_EOS (%d<%d)\n",

				  dmalen0, devpriv->ai_n_realscanlen << 1);

				  dmalen0, scan_bytes);

		} else {

			/* short first DMA buffer to one scan */

			dmalen0 = devpriv->ai_n_realscanlen << 1;

			dmalen0 = scan_bytes;

			if (dmalen0 < 4) {

				dev_info(dev->class_dev,

					 "ERR: DMA0 buf len bug? (%d<4)\n",
@@ -835,15 +836,15 @@ static int pci9118_ai_setup_dma(struct comedi_device *dev, 
		}

	}

	if (devpriv->ai_flags & CMDF_WAKE_EOS) {

		if (dmalen1 < (devpriv->ai_n_realscanlen << 1)) {

		if (dmalen1 < scan_bytes) {

			/* uff, too short DMA buffer, disable EOS support! */

			devpriv->ai_flags &= (~CMDF_WAKE_EOS);

			dev_info(dev->class_dev,

				 "WAR: DMA1 buf too short, can't support CMDF_WAKE_EOS (%d<%d)\n",

				 dmalen1, devpriv->ai_n_realscanlen << 1);

				 dmalen1, scan_bytes);

		} else {

			/* short second DMA buffer to one scan */

			dmalen1 = devpriv->ai_n_realscanlen << 1;

			dmalen1 = scan_bytes;

			if (dmalen1 < 4) {

				dev_info(dev->class_dev,

					 "ERR: DMA1 buf len bug? (%d<4)\n",
@@ -855,48 +856,42 @@ static int pci9118_ai_setup_dma(struct comedi_device *dev, 


	/* transfer without CMDF_WAKE_EOS */

	if (!(devpriv->ai_flags & CMDF_WAKE_EOS)) {

		unsigned int tmp;



		/* if it's possible then align DMA buffers to length of scan */

		i = dmalen0;

		dmalen0 =

		    (dmalen0 / (devpriv->ai_n_realscanlen << 1)) *

		    (devpriv->ai_n_realscanlen << 1);

		tmp = dmalen0;

		dmalen0 = (dmalen0 / scan_bytes) * scan_bytes;

		dmalen0 &= ~3L;

		if (!dmalen0)

			dmalen0 = i;	/* uff. very long scan? */

		i = dmalen1;

		dmalen1 =

		    (dmalen1 / (devpriv->ai_n_realscanlen << 1)) *

		    (devpriv->ai_n_realscanlen << 1);

			dmalen0 = tmp;	/* uff. very long scan? */

		tmp = dmalen1;

		dmalen1 = (dmalen1 / scan_bytes) * scan_bytes;

		dmalen1 &= ~3L;

		if (!dmalen1)

			dmalen1 = i;	/* uff. very long scan? */

			dmalen1 = tmp;	/* uff. very long scan? */

		/*

		 * if measure isn't neverending then test, if it fits whole

		 * into one or two DMA buffers

		 */

		if (!devpriv->ai_neverending) {

			/* fits whole measure into one DMA buffer? */

			if (dmalen0 >

			    ((devpriv->ai_n_realscanlen << 1) *

			     cmd->stop_arg)) {

				dmalen0 =

				    (devpriv->ai_n_realscanlen << 1) *

			unsigned long long scanlen;



			scanlen = (unsigned long long)scan_bytes *

				  cmd->stop_arg;



			/* fits whole measure into one DMA buffer? */

			if (dmalen0 > scanlen) {

				dmalen0 = scanlen;

				dmalen0 &= ~3L;

			} else {	/*

					 * fits whole measure into

					 * two DMA buffer?

					 */

				if (dmalen1 >

				    ((devpriv->ai_n_realscanlen << 1) *

				     cmd->stop_arg - dmalen0))

					dmalen1 =

					    (devpriv->ai_n_realscanlen << 1) *

					    cmd->stop_arg - dmalen0;

			} else {

				/* fits whole measure into two DMA buffer? */

				if (dmalen1 > (scanlen - dmalen0)) {

					dmalen1 = scanlen - dmalen0;

					dmalen1 &= ~3L;

				}

			}

		}

	}



	/* these DMA buffer size will be used */

	devpriv->dma_actbuf = 0;