[PATCH V2 0/4] Remove WARN_ON in save_processor_state

[PATCH V2 0/4] Remove WARN_ON in save_processor_state

[Song Shuai]

During hibernation or restoration, freeze_secondary_cpus
checks num_online_cpus via BUG_ON, and the subsequent
save_processor_state also does the checking with WARN_ON.

In the case of CONFIG_PM_SLEEP_SMP=n, freeze_secondary_cpus
is not defined, but the sole possible condition to disable 
CONFIG_PM_SLEEP_SMP is !SMP where num_online_cpus is always 1.
We also don't have to check it in save_processor_state.

So remove the unnecessary checking in save_processor_state
for ARM,arm64,riscv,xtensa architechtures.

Changes since V1:
https://lore.kernel.org/linux-riscv/20230525025555.24104-1-songshuaishuai@tinylab.org/
- supplement the case of CONFIG_PM_SLEEP_SMP=n in commit message as Will suggests

Song Shuai (4):
  ARM: hibernate: remove WARN_ON in save_processor_state
  arm64: hibernate: remove WARN_ON in save_processor_state
  riscv: hibernate: remove WARN_ON in save_processor_state
  xtensa: hibernate: remove WARN_ON in save_processor_state

 arch/arm/kernel/hibernate.c    | 1 -
 arch/arm64/kernel/hibernate.c  | 1 -
 arch/riscv/kernel/hibernate.c  | 1 -
 arch/xtensa/kernel/hibernate.c | 1 -
 4 files changed, 4 deletions(-)

-- 
2.20.1


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[PATCH V2 1/4] ARM: hibernate: remove WARN_ON in save_processor_state

[Song Shuai]

During hibernation or restoration, freeze_secondary_cpus
checks num_online_cpus via BUG_ON, and the subsequent
save_processor_state also does the checking with WARN_ON.

In the case of CONFIG_PM_SLEEP_SMP=n, freeze_secondary_cpus
is not defined, but the sole possible condition to disable
CONFIG_PM_SLEEP_SMP is !SMP where num_online_cpus is always 1.
We also don't have to check it in save_processor_state.

So remove the unnecessary checking in save_processor_state.

Signed-off-by: Song Shuai <songshuaishuai@tinylab.org>
---
 arch/arm/kernel/hibernate.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/arm/kernel/hibernate.c b/arch/arm/kernel/hibernate.c
index 2373020af965..84abccf3221a 100644
--- a/arch/arm/kernel/hibernate.c
+++ b/arch/arm/kernel/hibernate.c
@@ -33,7 +33,6 @@ int pfn_is_nosave(unsigned long pfn)
 
 void notrace save_processor_state(void)
 {
-	WARN_ON(num_online_cpus() != 1);
 	local_fiq_disable();
 }
 
-- 
2.20.1


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[PATCH V2 2/4] arm64: hibernate: remove WARN_ON in save_processor_state

[Song Shuai]

During hibernation or restoration, freeze_secondary_cpus
checks num_online_cpus via BUG_ON, and the subsequent
save_processor_state also does the checking with WARN_ON.

In the case of CONFIG_PM_SLEEP_SMP=n, freeze_secondary_cpus
is not defined, but the sole possible condition to disable
CONFIG_PM_SLEEP_SMP is !SMP where num_online_cpus is always 1.
We also don't have to check it in save_processor_state.

So remove the unnecessary checking in save_processor_state.

Signed-off-by: Song Shuai <songshuaishuai@tinylab.org>
---
 arch/arm64/kernel/hibernate.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c
index 788597a6b6a2..02870beb271e 100644
--- a/arch/arm64/kernel/hibernate.c
+++ b/arch/arm64/kernel/hibernate.c
@@ -99,7 +99,6 @@ int pfn_is_nosave(unsigned long pfn)
 
 void notrace save_processor_state(void)
 {
-	WARN_ON(num_online_cpus() != 1);
 }
 
 void notrace restore_processor_state(void)
-- 
2.20.1


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Re: [PATCH V2 2/4] arm64: hibernate: remove WARN_ON in save_processor_state

[Will Deacon]

On Fri, Jun 09, 2023 at 03:50:47PM +0800, Song Shuai wrote:
> During hibernation or restoration, freeze_secondary_cpus
> checks num_online_cpus via BUG_ON, and the subsequent
> save_processor_state also does the checking with WARN_ON.
> 
> In the case of CONFIG_PM_SLEEP_SMP=n, freeze_secondary_cpus
> is not defined, but the sole possible condition to disable
> CONFIG_PM_SLEEP_SMP is !SMP where num_online_cpus is always 1.
> We also don't have to check it in save_processor_state.
> 
> So remove the unnecessary checking in save_processor_state.
> 
> Signed-off-by: Song Shuai <songshuaishuai@tinylab.org>
> ---
>  arch/arm64/kernel/hibernate.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c
> index 788597a6b6a2..02870beb271e 100644
> --- a/arch/arm64/kernel/hibernate.c
> +++ b/arch/arm64/kernel/hibernate.c
> @@ -99,7 +99,6 @@ int pfn_is_nosave(unsigned long pfn)
>  
>  void notrace save_processor_state(void)
>  {
> -	WARN_ON(num_online_cpus() != 1);
>  }
>  
>  void notrace restore_processor_state(void)

Acked-by: Will Deacon <will@kernel.org>

Thanks!

Will

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[PATCH V2 3/4] riscv: hibernate: remove WARN_ON in save_processor_state

[Song Shuai]

During hibernation or restoration, freeze_secondary_cpus
checks num_online_cpus via BUG_ON, and the subsequent
save_processor_state also does the checking with WARN_ON.

In the case of CONFIG_PM_SLEEP_SMP=n, freeze_secondary_cpus
is not defined, but the sole possible condition to disable
CONFIG_PM_SLEEP_SMP is !SMP where num_online_cpus is always 1.
We also don't have to check it in save_processor_state.

So remove the unnecessary checking in save_processor_state.

Fixes: c0317210012e ("RISC-V: Add arch functions to support hibernation/suspend-to-disk")
Signed-off-by: Song Shuai <songshuaishuai@tinylab.org>
---
 arch/riscv/kernel/hibernate.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/riscv/kernel/hibernate.c b/arch/riscv/kernel/hibernate.c
index 395f835f067c..86f1c9ab6b0b 100644
--- a/arch/riscv/kernel/hibernate.c
+++ b/arch/riscv/kernel/hibernate.c
@@ -119,7 +119,6 @@ int pfn_is_nosave(unsigned long pfn)
 
 void notrace save_processor_state(void)
 {
-	WARN_ON(num_online_cpus() != 1);
 }
 
 void notrace restore_processor_state(void)
-- 
2.20.1


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Re: [PATCH V2 3/4] riscv: hibernate: remove WARN_ON in save_processor_state

[Conor Dooley]

[-- Attachment #1.1: Type: text/plain, Size: 1600 bytes --]

On Fri, Jun 09, 2023 at 03:50:48PM +0800, Song Shuai wrote:
> During hibernation or restoration, freeze_secondary_cpus
> checks num_online_cpus via BUG_ON, and the subsequent
> save_processor_state also does the checking with WARN_ON.
> 
> In the case of CONFIG_PM_SLEEP_SMP=n, freeze_secondary_cpus
> is not defined, but the sole possible condition to disable
> CONFIG_PM_SLEEP_SMP is !SMP where num_online_cpus is always 1.
> We also don't have to check it in save_processor_state.
> 
> So remove the unnecessary checking in save_processor_state.

In the future, please write function with a () in commit
messages, so freeze_secondary_cpus() etc.
Otherwise,
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>

Thanks,
Conor.

> 
> Fixes: c0317210012e ("RISC-V: Add arch functions to support hibernation/suspend-to-disk")
> Signed-off-by: Song Shuai <songshuaishuai@tinylab.org>
> ---
>  arch/riscv/kernel/hibernate.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/arch/riscv/kernel/hibernate.c b/arch/riscv/kernel/hibernate.c
> index 395f835f067c..86f1c9ab6b0b 100644
> --- a/arch/riscv/kernel/hibernate.c
> +++ b/arch/riscv/kernel/hibernate.c
> @@ -119,7 +119,6 @@ int pfn_is_nosave(unsigned long pfn)
>  
>  void notrace save_processor_state(void)
>  {
> -	WARN_ON(num_online_cpus() != 1);
>  }
>  
>  void notrace restore_processor_state(void)
> -- 
> 2.20.1
> 
> 
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv

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[PATCH V2 4/4] xtensa: hibernate: remove WARN_ON in save_processor_state

[Song Shuai]

During hibernation or restoration, freeze_secondary_cpus
checks num_online_cpus via BUG_ON, and the subsequent
save_processor_state also does the checking with WARN_ON.

In the case of CONFIG_PM_SLEEP_SMP=n, freeze_secondary_cpus
is not defined, but the sole possible condition to disable
CONFIG_PM_SLEEP_SMP is !SMP where num_online_cpus is always 1.
We also don't have to check it in save_processor_state.

So remove the unnecessary checking in save_processor_state.

Signed-off-by: Song Shuai <songshuaishuai@tinylab.org>
---
 arch/xtensa/kernel/hibernate.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/xtensa/kernel/hibernate.c b/arch/xtensa/kernel/hibernate.c
index 06984327d6e2..314602bbf431 100644
--- a/arch/xtensa/kernel/hibernate.c
+++ b/arch/xtensa/kernel/hibernate.c
@@ -14,7 +14,6 @@ int pfn_is_nosave(unsigned long pfn)
 
 void notrace save_processor_state(void)
 {
-	WARN_ON(num_online_cpus() != 1);
 #if XTENSA_HAVE_COPROCESSORS
 	local_coprocessors_flush_release_all();
 #endif
-- 
2.20.1


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Re: (subset) [PATCH V2 0/4] Remove WARN_ON in save_processor_state

[Catalin Marinas]

On Fri, 09 Jun 2023 15:50:45 +0800, Song Shuai wrote:
> During hibernation or restoration, freeze_secondary_cpus
> checks num_online_cpus via BUG_ON, and the subsequent
> save_processor_state also does the checking with WARN_ON.
> 
> In the case of CONFIG_PM_SLEEP_SMP=n, freeze_secondary_cpus
> is not defined, but the sole possible condition to disable
> CONFIG_PM_SLEEP_SMP is !SMP where num_online_cpus is always 1.
> We also don't have to check it in save_processor_state.
> 
> [...]

Applied to arm64 (for-next/misc), thanks!

I couldn't tell whether this series would go in as a whole but given
that the patches are independent, I picked up the arm64 one.

[2/4] arm64: hibernate: remove WARN_ON in save_processor_state
      https://git.kernel.org/arm64/c/615af0021a61

-- 
Catalin


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Re: (subset) [PATCH V2 0/4] Remove WARN_ON in save_processor_state

[Palmer Dabbelt]

On Wed, 21 Jun 2023 08:51:43 PDT (-0700), Catalin Marinas wrote:
> On Fri, 09 Jun 2023 15:50:45 +0800, Song Shuai wrote:
>> During hibernation or restoration, freeze_secondary_cpus
>> checks num_online_cpus via BUG_ON, and the subsequent
>> save_processor_state also does the checking with WARN_ON.
>>
>> In the case of CONFIG_PM_SLEEP_SMP=n, freeze_secondary_cpus
>> is not defined, but the sole possible condition to disable
>> CONFIG_PM_SLEEP_SMP is !SMP where num_online_cpus is always 1.
>> We also don't have to check it in save_processor_state.
>>
>> [...]
>
> Applied to arm64 (for-next/misc), thanks!
>
> I couldn't tell whether this series would go in as a whole but given
> that the patches are independent, I picked up the arm64 one.
>
> [2/4] arm64: hibernate: remove WARN_ON in save_processor_state
>       https://git.kernel.org/arm64/c/615af0021a61

I was pretty much in the same spot until I saw this, so I'm picking the 
RISC-V bit and just ignoring the rest.  It's testing so it might take a bit to
land in linux-next, but seems pretty safe.

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Re: (subset) [PATCH V2 0/4] Remove WARN_ON in save_processor_state

[Palmer Dabbelt]

On Fri, 09 Jun 2023 15:50:45 +0800, Song Shuai wrote:
> During hibernation or restoration, freeze_secondary_cpus
> checks num_online_cpus via BUG_ON, and the subsequent
> save_processor_state also does the checking with WARN_ON.
> 
> In the case of CONFIG_PM_SLEEP_SMP=n, freeze_secondary_cpus
> is not defined, but the sole possible condition to disable
> CONFIG_PM_SLEEP_SMP is !SMP where num_online_cpus is always 1.
> We also don't have to check it in save_processor_state.
> 
> [...]

Applied, thanks!

[3/4] riscv: hibernate: remove WARN_ON in save_processor_state
      https://git.kernel.org/palmer/c/91afbaafd6b1

Best regards,
-- 
Palmer Dabbelt <palmer@rivosinc.com>


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Re: [PATCH V2 0/4] Remove WARN_ON in save_processor_state

[patchwork-bot+linux-riscv]

Hello:

This series was applied to riscv/linux.git (for-next)
by Palmer Dabbelt <palmer@rivosinc.com>:

On Fri,  9 Jun 2023 15:50:45 +0800 you wrote:
> During hibernation or restoration, freeze_secondary_cpus
> checks num_online_cpus via BUG_ON, and the subsequent
> save_processor_state also does the checking with WARN_ON.
> 
> In the case of CONFIG_PM_SLEEP_SMP=n, freeze_secondary_cpus
> is not defined, but the sole possible condition to disable
> CONFIG_PM_SLEEP_SMP is !SMP where num_online_cpus is always 1.
> We also don't have to check it in save_processor_state.
> 
> [...]

Here is the summary with links:
  - [V2,1/4] ARM: hibernate: remove WARN_ON in save_processor_state
    (no matching commit)
  - [V2,2/4] arm64: hibernate: remove WARN_ON in save_processor_state
    (no matching commit)
  - [V2,3/4] riscv: hibernate: remove WARN_ON in save_processor_state
    https://git.kernel.org/riscv/c/91afbaafd6b1
  - [V2,4/4] xtensa: hibernate: remove WARN_ON in save_processor_state
    (no matching commit)

You are awesome, thank you!
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