On Mon, Jul 29, 2019 at 09:19:05PM +0200, Greg Kroah-Hartman wrote:
> [ Upstream commit 509466b7d480bc5d22e90b9fbe6122ae0e2fbe39 ]
>
> runnable_avg_yN_inv[] is only used in kernel/sched/pelt.c but was
> included in several other places because they need other macros all
> came from kernel/sched/sched-pelt.h which was generated by
> Documentation/scheduler/sched-pelt. As the result, it causes compilation
> a lot of warnings,
>
> kernel/sched/sched-pelt.h:4:18: warning: 'runnable_avg_yN_inv' defined but
> not used [-Wunused-const-variable=]
> kernel/sched/sched-pelt.h:4:18: warning: 'runnable_avg_yN_inv' defined but
> not used [-Wunused-const-variable=]
> kernel/sched/sched-pelt.h:4:18: warning: 'runnable_avg_yN_inv' defined but
> not used [-Wunused-const-variable=]
> ...
>
> Silence it by appending the __maybe_unused attribute for it, so all
> generated variables and macros can still be kept in the same file.
>
> Signed-off-by: Qian Cai <[email protected]>
> Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
> Cc: Linus Torvalds <[email protected]>
> Cc: Peter Zijlstra <[email protected]>
> Cc: Thomas Gleixner <[email protected]>
> Link: https://lkml.kernel.org/r/[email protected]
> Signed-off-by: Ingo Molnar <[email protected]>
> Signed-off-by: Sasha Levin <[email protected]>
> ---
> Documentation/scheduler/sched-pelt.c | 3 ++-
> kernel/sched/sched-pelt.h | 2 +-
> 2 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/scheduler/sched-pelt.c
> b/Documentation/scheduler/sched-pelt.c
> index e4219139386a..7238b355919c 100644
> --- a/Documentation/scheduler/sched-pelt.c
> +++ b/Documentation/scheduler/sched-pelt.c
> @@ -20,7 +20,8 @@ void calc_runnable_avg_yN_inv(void)
> int i;
> unsigned int x;
>
> - printf("static const u32 runnable_avg_yN_inv[] = {");
> + /* To silence -Wunused-but-set-variable warnings. */
> + printf("static const u32 runnable_avg_yN_inv[] __maybe_unused = {");
> for (i = 0; i < HALFLIFE; i++) {
> x = ((1UL<<32)-1)*pow(y, i);
>
> diff --git a/kernel/sched/sched-pelt.h b/kernel/sched/sched-pelt.h
> index a26473674fb7..c529706bed11 100644
> --- a/kernel/sched/sched-pelt.h
> +++ b/kernel/sched/sched-pelt.h
> @@ -1,7 +1,7 @@
> /* SPDX-License-Identifier: GPL-2.0 */
> /* Generated by Documentation/scheduler/sched-pelt; do not modify. */
>
> -static const u32 runnable_avg_yN_inv[] = {
> +static const u32 runnable_avg_yN_inv[] __maybe_unused = {
> 0xffffffff, 0xfa83b2da, 0xf5257d14, 0xefe4b99a, 0xeac0c6e6, 0xe5b906e6,
> 0xe0ccdeeb, 0xdbfbb796, 0xd744fcc9, 0xd2a81d91, 0xce248c14, 0xc9b9bd85,
> 0xc5672a10, 0xc12c4cc9, 0xbd08a39e, 0xb8fbaf46, 0xb504f333, 0xb123f581,
> --
> 2.20.1
>
>
>
This patch does nothing in 4.14. There is no kernel/sched/pelt.c.
$ fd pelt
kernel/sched/sched-pelt.h
Documentation/scheduler/sched-pelt.c
runnable_avg_yN_inv is only used in one location in 4.14.134, in fair.c
behind CONFIG_SMP, which is also the guard that includes sched-pelt.h.
$ rg --no-heading -g '!Documentation' runnable_avg_yN_inv
kernel/sched/sched-pelt.h:4:static const u32 runnable_avg_yN_inv[] = {
kernel/sched/fair.c:2849: val = mul_u64_u32_shr(val,
runnable_avg_yN_inv[local_n], 32);
$ rg --no-heading -B 2 "sched-pelt.h"
kernel/sched/fair.c-707-#ifdef CONFIG_SMP
kernel/sched/fair.c-708-
kernel/sched/fair.c:709:#include "sched-pelt.h"
I see no way for the warnings in this patch to occur here, making it
pointless. I get two trivial conflicts in my msm-4.14 tree from this
patch that I would like to avoid dealing with.
Please consider dropping this patch, thanks!
Nathan
