From 3c21cfc4babaf4d20384f6f70def308e9b945159 Mon Sep 17 00:00:00 2001 From: Daniel Drake Date: Wed, 18 Oct 2006 21:37:14 +0100 Subject: [PATCH] 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 Signed-off-by: Stefan Richter --- drivers/ieee1394/video1394.c | 18 ++++++++++-------- 1 file 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; -- 2.20.1