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video1394: small optimizations to frame retrieval codepath 

Add some GCC branch prediction optimizations to unlikely error/safety
conditions in the ioctl handling code commonly called during an application's
capture loop.

Signed-off-by: Daniel Drake <ddrake@brontes3d.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
This commit is contained in:
Daniel Drake 2006-10-18 21:37:14 +01:00 committed by Stefan Richter
parent c1c9c7cd9f
commit 3c21cfc4ba
1 changed files with 10 additions and 8 deletions
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18
drivers/ieee1394/video1394.c
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@ -884,13 +884,14 @@ static int __video1394_ioctl(struct file *file,
struct dma_iso_ctx *d;
int next_prg;
if (copy_from_user(&v, argp, sizeof(v)))
if (unlikely(copy_from_user(&v, argp, sizeof(v))))
return -EFAULT;
d = find_ctx(&ctx->context_list, OHCI_ISO_RECEIVE, v.channel);
if (d == NULL) return -EFAULT;
if (unlikely(d == NULL))
return -EFAULT;
if ((v.buffer<0) || (v.buffer>=d->num_desc - 1)) {
if (unlikely((v.buffer<0) || (v.buffer>=d->num_desc - 1))) {
PRINT(KERN_ERR, ohci->host->id,
"Buffer %d out of range",v.buffer);
return -EINVAL;
@ -898,7 +899,7 @@ static int __video1394_ioctl(struct file *file,
spin_lock_irqsave(&d->lock,flags);
if (d->buffer_status[v.buffer]==VIDEO1394_BUFFER_QUEUED) {
if (unlikely(d->buffer_status[v.buffer]==VIDEO1394_BUFFER_QUEUED)) {
PRINT(KERN_ERR, ohci->host->id,
"Buffer %d is already used",v.buffer);
spin_unlock_irqrestore(&d->lock,flags);
@ -949,13 +950,14 @@ static int __video1394_ioctl(struct file *file,
struct dma_iso_ctx *d;
int i = 0;
if (copy_from_user(&v, argp, sizeof(v)))
if (unlikely(copy_from_user(&v, argp, sizeof(v))))
return -EFAULT;
d = find_ctx(&ctx->context_list, OHCI_ISO_RECEIVE, v.channel);
if (d == NULL) return -EFAULT;
if (unlikely(d == NULL))
return -EFAULT;
if ((v.buffer<0) || (v.buffer>d->num_desc - 1)) {
if (unlikely((v.buffer<0) || (v.buffer>d->num_desc - 1))) {
PRINT(KERN_ERR, ohci->host->id,
"Buffer %d out of range",v.buffer);
return -EINVAL;
@ -1008,7 +1010,7 @@ static int __video1394_ioctl(struct file *file,
spin_unlock_irqrestore(&d->lock, flags);
v.buffer=i;
if (copy_to_user(argp, &v, sizeof(v)))
if (unlikely(copy_to_user(argp, &v, sizeof(v))))
return -EFAULT;
return 0;