[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Message-Id: <1296237350-6624-1-git-send-email-bosong.ly@taobao.com>
Date: Sat, 29 Jan 2011 01:55:45 +0800
From: Coly Li <bosong.ly@...bao.com>
To: linux-kernel@...r.kernel.org
Cc: Coly Li <bosong.ly@...bao.com>, Greg KH <gregkh@...e.de>,
Yong Zhang <yong.zhang0@...il.com>,
Wang Cong <xiyou.wangcong@...il.com>
Subject: [PATCH 0/5] use BUG_ON correctly, v3
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@...bao.com>
Cc: Greg KH <gregkh@...e.de>
Cc: Yong Zhang <yong.zhang0@...il.com>
Cc: Wang Cong <xiyou.wangcong@...il.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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists