diff options
| author | Daniel Drake <ddrake@brontes3d.com> | 2006-10-18 21:37:14 +0100 |
|---|---|---|
| committer | Stefan Richter <stefanr@s5r6.in-berlin.de> | 2006-12-07 21:31:04 +0100 |
| commit | 3c21cfc4babaf4d20384f6f70def308e9b945159 (patch) | |
| tree | a5bedb18e8df5fd6349f35053d55b3701aa025bf /drivers/ieee1394/video1394.c | |
| parent | c1c9c7cd9f33ad6ff4407638060fe2730560bd56 (diff) | |
| download | lwn-3c21cfc4babaf4d20384f6f70def308e9b945159.tar.gz lwn-3c21cfc4babaf4d20384f6f70def308e9b945159.zip | |
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>
Diffstat (limited to 'drivers/ieee1394/video1394.c')
| -rw-r--r-- | drivers/ieee1394/video1394.c | 18 |
1 files changed, 10 insertions, 8 deletions
diff --git a/drivers/ieee1394/video1394.c b/drivers/ieee1394/video1394.c index 9bc65059cc69..776b6618e80e 100644 --- a/drivers/ieee1394/video1394.c +++ b/drivers/ieee1394/video1394.c @@ -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; |