[PATCH] lib/vsprintf.c:Avoid extra operation in dentry_name

[PATCH] lib/vsprintf.c:Avoid extra operation in dentry_name

[Anshul Garg]

From: Anshul Garg <aksgarg1989@gmail.com>

Remove unnecessary increment and decrement operation
in dentry_name function as after increment operation
loop is breaked and then decrement operation is
performed. So remove increment and decrement operation
from the function.

Signed-off-by: Anshul Garg <aksgarg1989@gmail.com>
---
 lib/vsprintf.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index ec337f6..2a38105 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -576,11 +576,10 @@ char *dentry_name(char *buf, char *end, const struct dentry *d, struct printf_sp
 		if (p == d) {
 			if (i)
 				array[i] = "";
-			i++;
 			break;
 		}
 	}
-	s = array[--i];
+	s = array[i];
 	for (n = 0; n != spec.precision; n++, buf++) {
 		char c = *s++;
 		if (!c) {
-- 
1.7.9.5


---
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Re: [PATCH] lib/vsprintf.c:Avoid extra operation in dentry_name

[Richard Weinberger]

On Mon, Feb 16, 2015 at 7:49 PM, Anshul Garg <aksgarg1989@gmail.com> wrote:
> From: Anshul Garg <aksgarg1989@gmail.com>
>
> Remove unnecessary increment and decrement operation
> in dentry_name function as after increment operation
> loop is breaked and then decrement operation is
> performed. So remove increment and decrement operation
> from the function.
>
> Signed-off-by: Anshul Garg <aksgarg1989@gmail.com>
> ---
>  lib/vsprintf.c |    3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index ec337f6..2a38105 100644
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -576,11 +576,10 @@ char *dentry_name(char *buf, char *end, const struct dentry *d, struct printf_sp
>                 if (p == d) {
>                         if (i)
>                                 array[i] = "";
> -                       i++;
>                         break;
>                 }
>         }
> -       s = array[--i];
> +       s = array[i];
>         for (n = 0; n != spec.precision; n++, buf++) {
>                 char c = *s++;
>                 if (!c) {

What if the if (d == d) branch is not taken?
Does the code then really behave exactly as before?

-- 
Thanks,
//richard

Re: [PATCH] lib/vsprintf.c:Avoid extra operation in dentry_name

[Anshul Garg]

Yes suggested code modification will break if (p==d) branch is not taken.
Thanks for pointing out this point.

So its better to keep code as it is.

On Tue, Feb 17, 2015 at 12:44 AM, Richard Weinberger
<richard.weinberger@gmail.com> wrote:
> On Mon, Feb 16, 2015 at 7:49 PM, Anshul Garg <aksgarg1989@gmail.com> wrote:
>> From: Anshul Garg <aksgarg1989@gmail.com>
>>
>> Remove unnecessary increment and decrement operation
>> in dentry_name function as after increment operation
>> loop is breaked and then decrement operation is
>> performed. So remove increment and decrement operation
>> from the function.
>>
>> Signed-off-by: Anshul Garg <aksgarg1989@gmail.com>
>> ---
>>  lib/vsprintf.c |    3 +--
>>  1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
>> index ec337f6..2a38105 100644
>> --- a/lib/vsprintf.c
>> +++ b/lib/vsprintf.c
>> @@ -576,11 +576,10 @@ char *dentry_name(char *buf, char *end, const struct dentry *d, struct printf_sp
>>                 if (p == d) {
>>                         if (i)
>>                                 array[i] = "";
>> -                       i++;
>>                         break;
>>                 }
>>         }
>> -       s = array[--i];
>> +       s = array[i];
>>         for (n = 0; n != spec.precision; n++, buf++) {
>>                 char c = *s++;
>>                 if (!c) {
>
> What if the if (d == d) branch is not taken?
> Does the code then really behave exactly as before?
>
> --
> Thanks,
> //richard