linux-kernel - Re: [PATCH] arch/h8300: modify ffs(), fls() etc. functions to return int

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Date:   Sun, 22 Jul 2018 11:02:26 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Richard Kuo <rkuo@...eaurora.org>,
        "open list:QUALCOMM HEXAGON..." <linux-hexagon@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Rich Felker <dalias@...c.org>,
        Linux-sh list <linux-sh@...r.kernel.org>
Subject: Re: [PATCH] arch/h8300: modify ffs(), fls() etc. functions to return
 int

On 07/22/2018 02:25 AM, Geert Uytterhoeven wrote:
> CC hexagon
> 
> hexagon != H8/300 != SuperH
> 
> On Sat, Jul 21, 2018 at 5:28 AM Randy Dunlap <rdunlap@...radead.org> wrote:
>>
>> From: Randy Dunlap <rdunlap@...radead.org>
>>
>> Building drivers/mtd/nand/raw/nandsim.c on arch/hexagon/ produces a
>> printk format build warning.  This is due to hexagon's ffs() being
>> coded as returning long instead of int.
>>
>> Fix the printk format warning by changing all of hexagon's ffx() and
>> flx() functions to return int instead of long.  The variables that
>> they return are already int instead of long.
>>
>> ../drivers/mtd/nand/raw/nandsim.c: In function 'init_nandsim':
>> ../drivers/mtd/nand/raw/nandsim.c:760:2: warning: format '%u' expects argument of type 'unsigned int', but argument 2 has type 'long int' [-Wformat]
>>
>>
>> There are no ffx() or flx() allmodconfig build errors after making this
>> change.
>>
>> Signed-off-by: Randy Dunlap <rdunlap@...radead.org>
>> Cc: Yoshinori Sato <ysato@...rs.sourceforge.jp>
>> Cc: Rich Felker <dalias@...c.org>
>> Cc: linux-sh@...r.kernel.org
>> ---
>>  arch/hexagon/include/asm/bitops.h |   10 +++++-----
>>  1 file changed, 5 insertions(+), 5 deletions(-)
>>
>> --- linux-next-20180717.orig/arch/hexagon/include/asm/bitops.h
>> +++ linux-next-20180717/arch/hexagon/include/asm/bitops.h
>> @@ -194,7 +194,7 @@ static inline int __test_bit(int nr, con
>>   *
>>   * Undefined if no zero exists, so code should check against ~0UL first.
>>   */
>> -static inline long ffz(int x)
>> +static inline int ffz(int x)
>>  {
>>         int r;
>>
>> @@ -211,7 +211,7 @@ static inline long ffz(int x)
>>   * This is defined the same way as ffs.
>>   * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
>>   */
>> -static inline long fls(int x)
>> +static inline int fls(int x)
>>  {
>>         int r;
>>
>> @@ -232,7 +232,7 @@ static inline long fls(int x)
>>   * the libc and compiler builtin ffs routines, therefore
>>   * differs in spirit from the above ffz (man ffs).
>>   */
>> -static inline long ffs(int x)
>> +static inline int ffs(int x)
>>  {
>>         int r;
>>
>> @@ -254,7 +254,7 @@ static inline long ffs(int x)
>>   * bits_per_long assumed to be 32
>>   * numbering starts at 0 I think (instead of 1 like ffs)
>>   */
>> -static inline unsigned long __ffs(unsigned long word)
>> +static inline int __ffs(unsigned long word)
> 
> The version in asm-generic deoes use "unsigned long".
> 
> See also "m68k/bitops: convert __ffs to match generic declaration"
> https://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k.git/commit/?h=for-v4.19&id=4b538d3dca3e590cdb0234746011a6d9c245cfa3
> 
>>  {
>>         int num;
>>
>> @@ -272,7 +272,7 @@ static inline unsigned long __ffs(unsign
>>   * Undefined if no set bit exists, so code should check against 0 first.
>>   * bits_per_long assumed to be 32
>>   */
>> -static inline unsigned long __fls(unsigned long word)
>> +static inline int __fls(unsigned long word)
> 
> Same here

Hi Geert,

Thanks for all your catches here.  So ffs() and fls() return int,
while __ffs() and __fls() return unsigned long.

(hm, arch/arc/include/asm/bitops.h is a little different.)
(and unicore32)


I'll send a v2 patch (for hexagon).
That will still fix the printk format warning above.

>>  {
>>         int num;


-- 
~Randy