[PATCH] cpuset: sparse warnings in cpuset.c

[PATCH] cpuset: sparse warnings in cpuset.c

[Harvey Harrison]

No need to redeclare p, we have finished with it at this point,
so reuse it in the for loop.

kernel/cpuset.c:824:23: warning: symbol 'p' shadows an earlier one
kernel/cpuset.c:746:21: originally declared here
kernel/cpuset.c:1272:52: warning: Using plain integer as NULL pointer

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
---
 kernel/cpuset.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index cfaf641..fdbac43 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -821,7 +821,7 @@ static int update_cpumask(struct cpuset *cs, char *buf)
 	cgroup_iter_end(cgrp, &it);
 	if (heap.size) {
 		for (i = 0; i < heap.size; i++) {
-			struct task_struct *p = heap.ptrs[i];
+			p = heap.ptrs[i];
 			if (i == 0) {
 				latest_time = p->start_time;
 				latest_task = p;
@@ -1269,7 +1269,8 @@ static ssize_t cpuset_common_file_write(struct cgroup *cont,
 		return -E2BIG;
 
 	/* +1 for nul-terminator */
-	if ((buffer = kmalloc(nbytes + 1, GFP_KERNEL)) == 0)
+	buffer = kmalloc(nbytes + 1, GFP_KERNEL);
+	if (!buffer)
 		return -ENOMEM;
 
 	if (copy_from_user(buffer, userbuf, nbytes)) {
-- 
1.5.4.rc5.1138.g2602

Re: [PATCH] cpuset: sparse warnings in cpuset.c

[Paul Jackson]

Harvey wrote:
> No need to redeclare p, we have finished with it at this point,
> so reuse it in the for loop.

Good catch, however I disagree with the fix.  It makes the code more
brittle.

It's not a good idea to reuse a variable for some other purpose just
because you "know" the original use is dead. Things don't necessarily
stay dead; code moves around.

Could you prepare a revised version of this patch, that instead of
dropping that declaration of 'p', rather renames it to 'q' ?

Thanks.

-- 
                  I won't rest till it's the best ...
                  Programmer, Linux Scalability
                  Paul Jackson <pj@sgi.com> 1.940.382.4214

Re: [PATCH] cpuset: sparse warnings in cpuset.c

[Harvey Harrison]

Don't redeclare p, use a new variable q.

kernel/cpuset.c:824:23: warning: symbol 'p' shadows an earlier one
kernel/cpuset.c:746:21: originally declared here
kernel/cpuset.c:1272:52: warning: Using plain integer as NULL pointer

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
---
Paul, used a variable q instead as per your request.

 kernel/cpuset.c |   13 +++++++------
 1 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index cfaf641..ce0cfff 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -821,13 +821,13 @@ static int update_cpumask(struct cpuset *cs, char *buf)
 	cgroup_iter_end(cgrp, &it);
 	if (heap.size) {
 		for (i = 0; i < heap.size; i++) {
-			struct task_struct *p = heap.ptrs[i];
+			struct task_struct *q = heap.ptrs[i];
 			if (i == 0) {
-				latest_time = p->start_time;
-				latest_task = p;
+				latest_time = q->start_time;
+				latest_task = q;
 			}
-			set_cpus_allowed(p, cs->cpus_allowed);
-			put_task_struct(p);
+			set_cpus_allowed(q, cs->cpus_allowed);
+			put_task_struct(q);
 		}
 		/*
 		 * If we had to process any tasks at all, scan again
@@ -1269,7 +1269,8 @@ static ssize_t cpuset_common_file_write(struct cgroup *cont,
 		return -E2BIG;
 
 	/* +1 for nul-terminator */
-	if ((buffer = kmalloc(nbytes + 1, GFP_KERNEL)) == 0)
+	buffer = kmalloc(nbytes + 1, GFP_KERNEL);
+	if (!buffer)
 		return -ENOMEM;
 
 	if (copy_from_user(buffer, userbuf, nbytes)) {
-- 
1.5.4.rc5.1138.g2602

Re: [PATCH] cpuset: sparse warnings in cpuset.c

[Paul Jackson]

Harvey wrote:
> Don't redeclare p, use a new variable q.

You dah man!  Thanks.

Acked-by: Paul Jackson <pj@sgi.com>

-- 
                  I won't rest till it's the best ...
                  Programmer, Linux Scalability
                  Paul Jackson <pj@sgi.com> 1.940.382.4214

Re: [PATCH] cpuset: sparse warnings in cpuset.c

[Andrew Morton]

On Sat, 02 Feb 2008 23:42:23 -0800 Harvey Harrison <harvey.harrison@gmail.com> wrote:

        ^^^^^^ I suck.

> Don't redeclare p, use a new variable q.
> 
> kernel/cpuset.c:824:23: warning: symbol 'p' shadows an earlier one
> kernel/cpuset.c:746:21: originally declared here
> kernel/cpuset.c:1272:52: warning: Using plain integer as NULL pointer
> 
> Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
> ---
> Paul, used a variable q instead as per your request.
> 
>  kernel/cpuset.c |   13 +++++++------
>  1 files changed, 7 insertions(+), 6 deletions(-)
> 
> diff --git a/kernel/cpuset.c b/kernel/cpuset.c
> index cfaf641..ce0cfff 100644
> --- a/kernel/cpuset.c
> +++ b/kernel/cpuset.c
> @@ -821,13 +821,13 @@ static int update_cpumask(struct cpuset *cs, char *buf)
>  	cgroup_iter_end(cgrp, &it);
>  	if (heap.size) {
>  		for (i = 0; i < heap.size; i++) {
> -			struct task_struct *p = heap.ptrs[i];
> +			struct task_struct *q = heap.ptrs[i];
>  			if (i == 0) {
> -				latest_time = p->start_time;
> -				latest_task = p;
> +				latest_time = q->start_time;
> +				latest_task = q;
>  			}
> -			set_cpus_allowed(p, cs->cpus_allowed);
> -			put_task_struct(p);
> +			set_cpus_allowed(q, cs->cpus_allowed);
> +			put_task_struct(q);
>  		}
>  		/*
>  		 * If we had to process any tasks at all, scan again

Sorry, the above code doesn't seem to exist any more.

Re: [PATCH] cpuset: sparse warnings in cpuset.c

[Paul Jackson]

akpm wrote:
> ^^^^^^ I suck.

Yeah, right ... and Dolly Parton is flat chested ;).

> Sorry, the above code doesn't seem to exist any more.

It moved from cpuset.c to cgroup.c.  I just sent a reincarnated patch:

  [PATCH] cgroup: fix sparse warning of shadow symbol in cgroup.c

-- 
                  I won't rest till it's the best ...
                  Programmer, Linux Scalability
                  Paul Jackson <pj@sgi.com> 1.940.382.4214