diff mbox series

[4.4,091/100] ext2: fix empty body warnings when -Wextra is used

Message ID 20200422095039.371486451@linuxfoundation.org
State Not Applicable
Headers show
Series None | expand

Commit Message

gregkh@linuxfoundation.org April 22, 2020, 9:57 a.m. UTC 
From: Randy Dunlap <rdunlap@infradead.org>

[ Upstream commit 44a52022e7f15cbaab957df1c14f7a4f527ef7cf ]

When EXT2_ATTR_DEBUG is not defined, modify the 2 debug macros
to use the no_printk() macro instead of <nothing>.
This fixes gcc warnings when -Wextra is used:

../fs/ext2/xattr.c:252:42: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
../fs/ext2/xattr.c:258:42: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
../fs/ext2/xattr.c:330:42: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
../fs/ext2/xattr.c:872:45: warning: suggest braces around empty body in an ‘else’ statement [-Wempty-body]

I have verified that the only object code change (with gcc 7.5.0) is
the reversal of some instructions from 'cmp a,b' to 'cmp b,a'.

Link: https://lore.kernel.org/r/e18a7395-61fb-2093-18e8-ed4f8cf56248@infradead.org
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Jan Kara <jack@suse.com>
Cc: linux-ext4@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/ext2/xattr.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Comments

Joe Perches April 25, 2020, 11:43 a.m. UTC | #1 
On Wed, 2020-04-22 at 11:57 +0200, Greg Kroah-Hartman wrote:
> From: Randy Dunlap <rdunlap@infradead.org>
> 
> [ Upstream commit 44a52022e7f15cbaab957df1c14f7a4f527ef7cf ]
> 
> When EXT2_ATTR_DEBUG is not defined, modify the 2 debug macros
> to use the no_printk() macro instead of <nothing>.
> This fixes gcc warnings when -Wextra is used:
> 
> ../fs/ext2/xattr.c:252:42: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
> ../fs/ext2/xattr.c:258:42: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
> ../fs/ext2/xattr.c:330:42: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
> ../fs/ext2/xattr.c:872:45: warning: suggest braces around empty body in an ‘else’ statement [-Wempty-body]
> 
> I have verified that the only object code change (with gcc 7.5.0) is
> the reversal of some instructions from 'cmp a,b' to 'cmp b,a'.

It'd be better to use the ext4 style defines:

fs/ext4/xattr.c:# define ea_idebug(inode, fmt, ...)                                     \
fs/ext4/xattr.c-        printk(KERN_DEBUG "inode %s:%lu: " fmt "\n",                    \
fs/ext4/xattr.c-               inode->i_sb->s_id, inode->i_ino, ##__VA_ARGS__)
fs/ext4/xattr.c:# define ea_bdebug(bh, fmt, ...)                                        \
fs/ext4/xattr.c-        printk(KERN_DEBUG "block %pg:%lu: " fmt "\n",                   \
fs/ext4/xattr.c-               bh->b_bdev, (unsigned long)bh->b_blocknr, ##__VA_ARGS__)
--
fs/ext4/xattr.c:# define ea_idebug(inode, fmt, ...)     no_printk(fmt, ##__VA_ARGS__)
fs/ext4/xattr.c:# define ea_bdebug(bh, fmt, ...)        no_printk(fmt, ##__VA_ARGS__)

So the output logging won't be split across multiple lines.

> diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c
[]
> @@ -55,6 +55,7 @@
>  
>  #include <linux/buffer_head.h>
>  #include <linux/init.h>
> +#include <linux/printk.h>
>  #include <linux/slab.h>
>  #include <linux/mbcache.h>
>  #include <linux/quotaops.h>
> @@ -85,8 +86,8 @@
>  		printk("\n"); \
>  	} while (0)
>  #else
> -# define ea_idebug(f...)
> -# define ea_bdebug(f...)
> +# define ea_idebug(inode, f...)	no_printk(f)
> +# define ea_bdebug(bh, f...)	no_printk(f)
>  #endif
>  
>  static int ext2_xattr_set2(struct inode *, struct buffer_head *,

---
 fs/ext2/xattr.c | 22 ++++++++--------------
 1 file changed, 8 insertions(+), 14 deletions(-)

diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c
index 943cc46..7740582 100644
--- a/fs/ext2/xattr.c
+++ b/fs/ext2/xattr.c
@@ -72,21 +72,15 @@
 #define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
 
 #ifdef EXT2_XATTR_DEBUG
-# define ea_idebug(inode, f...) do { \
-		printk(KERN_DEBUG "inode %s:%ld: ", \
-			inode->i_sb->s_id, inode->i_ino); \
-		printk(f); \
-		printk("\n"); \
-	} while (0)
-# define ea_bdebug(bh, f...) do { \
-		printk(KERN_DEBUG "block %pg:%lu: ", \
-			bh->b_bdev, (unsigned long) bh->b_blocknr); \
-		printk(f); \
-		printk("\n"); \
-	} while (0)
+# define ea_idebug(inode, fmt, ...)					\
+	printk(KERN_DEBUG "inode %s:%lu: " fmt "\n",			\
+	       inode->i_sb->s_id, inode->i_ino, ##__VA_ARGS__)
+# define ea_bdebug(bh, fmt, ...)					\
+	printk(KERN_DEBUG "block %pg:%lu: " fmt "\n",			\
+	       bh->b_bdev, (unsigned long)bh->b_blocknr, ##__VA_ARGS__)
 #else
-# define ea_idebug(inode, f...)	no_printk(f)
-# define ea_bdebug(bh, f...)	no_printk(f)
+# define ea_idebug(inode, fmt, ...)	no_printk(fmt, ##__VA_ARGS__)
+# define ea_bdebug(bh, fmt, ...)	no_printk(fmt, ##__VA_ARGS__)
 #endif
 
 static int ext2_xattr_set2(struct inode *, struct buffer_head *,
Joe Perches April 25, 2020, 11:47 a.m. UTC | #2 
On Sat, 2020-04-25 at 04:43 -0700, Joe Perches wrote:
> On Wed, 2020-04-22 at 11:57 +0200, Greg Kroah-Hartman wrote:
> > From: Randy Dunlap <rdunlap@infradead.org>
> > 
> > [ Upstream commit 44a52022e7f15cbaab957df1c14f7a4f527ef7cf ]
> > 
> > When EXT2_ATTR_DEBUG is not defined, modify the 2 debug macros
> > to use the no_printk() macro instead of <nothing>.
> > This fixes gcc warnings when -Wextra is used:
> > 
> > ../fs/ext2/xattr.c:252:42: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
> > ../fs/ext2/xattr.c:258:42: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
> > ../fs/ext2/xattr.c:330:42: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
> > ../fs/ext2/xattr.c:872:45: warning: suggest braces around empty body in an ‘else’ statement [-Wempty-body]
> > 
> > I have verified that the only object code change (with gcc 7.5.0) is
> > the reversal of some instructions from 'cmp a,b' to 'cmp b,a'.
> 
> It'd be better to use the ext4 style defines:
> 
> fs/ext4/xattr.c:# define ea_idebug(inode, fmt, ...)                                     \
> fs/ext4/xattr.c-        printk(KERN_DEBUG "inode %s:%lu: " fmt "\n",                    \
> fs/ext4/xattr.c-               inode->i_sb->s_id, inode->i_ino, ##__VA_ARGS__)
> fs/ext4/xattr.c:# define ea_bdebug(bh, fmt, ...)                                        \
> fs/ext4/xattr.c-        printk(KERN_DEBUG "block %pg:%lu: " fmt "\n",                   \
> fs/ext4/xattr.c-               bh->b_bdev, (unsigned long)bh->b_blocknr, ##__VA_ARGS__)
> --
> fs/ext4/xattr.c:# define ea_idebug(inode, fmt, ...)     no_printk(fmt, ##__VA_ARGS__)
> fs/ext4/xattr.c:# define ea_bdebug(bh, fmt, ...)        no_printk(fmt, ##__VA_ARGS__)
> 
> So the output logging won't be split across multiple lines.

And beyond that, why is a -Wextra warning being fixed in -stable at all?
diff mbox series

Patch

diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c
index 22d817dc821e9..6f6f4f89a2f0c 100644
--- a/fs/ext2/xattr.c
+++ b/fs/ext2/xattr.c
@@ -55,6 +55,7 @@ 
 
 #include <linux/buffer_head.h>
 #include <linux/init.h>
+#include <linux/printk.h>
 #include <linux/slab.h>
 #include <linux/mbcache.h>
 #include <linux/quotaops.h>
@@ -85,8 +86,8 @@ 
 		printk("\n"); \
 	} while (0)
 #else
-# define ea_idebug(f...)
-# define ea_bdebug(f...)
+# define ea_idebug(inode, f...)	no_printk(f)
+# define ea_bdebug(bh, f...)	no_printk(f)
 #endif
 
 static int ext2_xattr_set2(struct inode *, struct buffer_head *,