lkml.org 
[lkml]   [2019]   [Jun]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH v2] sched/core: silence a warning in sched_init()
On Tue, Jun 25, 2019 at 08:44:22AM -0400, Qian Cai wrote:
> Compiling a kernel with both FAIR_GROUP_SCHED=n and RT_GROUP_SCHED=n
> will generate a warning using W=1,
>
> kernel/sched/core.c: In function 'sched_init':
> kernel/sched/core.c:5906:32: warning: variable 'ptr' set but not used
> [-Wunused-but-set-variable]
> unsigned long alloc_size = 0, ptr;
> ^~~
>
> It apparently the maintainers don't like the previous fix [1] which
> contains ugly idefs, so silence it by appending the __maybe_unused
> attribute for it instead.
>
> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
> Signed-off-by: Qian Cai <cai@lca.pw>
> ---
>
> v2: Incorporate the feedback from Valentin.
>
> kernel/sched/core.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 874c427742a9..12b9b69c8a66 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -5903,7 +5903,8 @@ int in_sched_functions(unsigned long addr)
> void __init sched_init(void)
> {
> int i, j;
> - unsigned long alloc_size = 0, ptr;
> + unsigned long alloc_size = 0;
> + unsigned long __maybe_unused ptr;
>

That still isn't particularly pretty.

Why do we care about W=1 build noise? Some of that seems rather silly,
like that -Wmissing-prototype nonsense.

As to this one, ideally the compiler would not be stupid, and understand
the below, but alas.

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index fa43ce3962e7..cb652e165570 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6369,7 +6369,7 @@ DECLARE_PER_CPU(cpumask_var_t, select_idle_mask);

void __init sched_init(void)
{
- unsigned long alloc_size = 0, ptr;
+ unsigned long alloc_size = 0;
int i;

wait_bit_init();
@@ -6381,7 +6381,7 @@ void __init sched_init(void)
alloc_size += 2 * nr_cpu_ids * sizeof(void **);
#endif
if (alloc_size) {
- ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT);
+ unsigned long ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT);

#ifdef CONFIG_FAIR_GROUP_SCHED
root_task_group.se = (struct sched_entity **)ptr;
\
 
 \ /
  Last update: 2019-06-25 15:53    [W:0.067 / U:1.148 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site