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staging: comedi: adl_pci9118: tidy up pci9118_ai_setup_dma()

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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: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
H Hartley Sweeten 2015-10-19 13:13:05 -07:00 committed by Greg Kroah-Hartman
parent 45037a9569
commit eb96c7fc24
1 changed files with 31 additions and 36 deletions
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67
drivers/staging/comedi/drivers/adl_pci9118.c
View File

@ -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",
@ -855,45 +856,39 @@ 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) {
unsigned long long scanlen;
scanlen = (unsigned long long)scan_bytes *
cmd->stop_arg;
/* fits whole measure into one DMA buffer? */
if (dmalen0 >
((devpriv->ai_n_realscanlen << 1) *
cmd->stop_arg)) {
dmalen0 =
(devpriv->ai_n_realscanlen << 1) *
cmd->stop_arg;
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;
dmalen1 &= ~3L;
} else {
/* fits whole measure into two DMA buffer? */
if (dmalen1 > (scanlen - dmalen0)) {
dmalen1 = scanlen - dmalen0;
dmalen1 &= ~3L;
}
}
}
}