Messages in this thread Patch in this message | | | From | Coly Li <> | Subject | [PATCH 0/5] use BUG_ON correctly, v3 | Date | Sat, 29 Jan 2011 01:55:45 +0800 |
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Most of BUG_ON() implementations use unlikely() internally for better branch prediction results. The following method to use BUG_ON() with an explicit unlikely() doesn't make things better and is unwelcome: BUG_ON(unlikely(condition)); Source code should use BUG_ON() just with condition code.
For arch implementation of BUG_ON(), there are feed backs for v2 patch set from MIPS and PowerPC developers than neither explicit no implicit unlikely() does help anything.
Therefore using unlikely() explicit with BUG_ON() is always a bug. This patch set removes all incorrect BUG_ON() usage.
The difference between v3 and v2 patch set is 2 patches are removed from the patch set (since the modification is gratuitous): (1) [PATCH 1/7] MIPS: add unlikely() to BUG_ON() (2) [PATCH 2/7] PowerPC: add unlikely() to BUG_ON()
Signed-off-by: Coly Li <bosong.ly@taobao.com> Cc: Greg KH <gregkh@suse.de> Cc: Yong Zhang <yong.zhang0@gmail.com> Cc: Wang Cong <xiyou.wangcong@gmail.com> --- drivers/dma/iop-adma.c | 6 +++--- 1 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/dma/iop-adma.c b/drivers/dma/iop-adma.c index c6b01f5..e03f811 100644 --- a/drivers/dma/iop-adma.c +++ b/drivers/dma/iop-adma.c @@ -619,7 +619,7 @@ iop_adma_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dma_dest, if (unlikely(!len)) return NULL; - BUG_ON(unlikely(len > IOP_ADMA_MAX_BYTE_COUNT)); + BUG_ON(len > IOP_ADMA_MAX_BYTE_COUNT); dev_dbg(iop_chan->device->common.dev, "%s len: %u\n", __func__, len); @@ -652,7 +652,7 @@ iop_adma_prep_dma_memset(struct dma_chan *chan, dma_addr_t dma_dest, if (unlikely(!len)) return NULL; - BUG_ON(unlikely(len > IOP_ADMA_MAX_BYTE_COUNT)); + BUG_ON(len > IOP_ADMA_MAX_BYTE_COUNT); dev_dbg(iop_chan->device->common.dev, "%s len: %u\n", __func__, len); @@ -686,7 +686,7 @@ iop_adma_prep_dma_xor(struct dma_chan *chan, dma_addr_t dma_dest, if (unlikely(!len)) return NULL; - BUG_ON(unlikely(len > IOP_ADMA_XOR_MAX_BYTE_COUNT)); + BUG_ON(len > IOP_ADMA_XOR_MAX_BYTE_COUNT); dev_dbg(iop_chan->device->common.dev, "%s src_cnt: %d len: %u flags: %lx\n", -- 1.7.3.4
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