diff mbox

block: precedence bug in bio_set_op_attrs() macro

Message ID 20161110200438.GA22854@mwanda (mailing list archive)
State New, archived
Headers show

Commit Message

Dan Carpenter Nov. 10, 2016, 8:04 p.m. UTC
This code causes a problem for flush_epd_write_bio() because | has
higher precedence than ?: so it basically turns into:

	((bio)->bi_opf |= REQ_SYNC;

Which is wrong.

Fixes: ef295ecf090d ("block: better op and flags encoding")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

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Comments

Christoph Hellwig Nov. 10, 2016, 8:07 p.m. UTC | #1
On Thu, Nov 10, 2016 at 11:04:38PM +0300, Dan Carpenter wrote:
> This code causes a problem for flush_epd_write_bio() because | has
> higher precedence than ?: so it basically turns into:
> 
> 	((bio)->bi_opf |= REQ_SYNC;
> 
> Which is wrong.

Its is.  And while we're at it the macro should really be doing a
= instead of |=.

And we really should stop using it, at least in the block core even
ASAP.
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diff mbox

Patch

diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 562ac46..67fae32 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -208,7 +208,7 @@  enum req_flag_bits {
 
 /* obsolete, don't use in new code */
 #define bio_set_op_attrs(bio, op, op_flags) \
-	((bio)->bi_opf |= (op | op_flags))
+	((bio)->bi_opf |= ((op) | (op_flags)))
 
 static inline bool op_is_write(unsigned int op)
 {