[RFC,v3,1/3] fadump: Refactor and prepare fadump_cma_init for late init

Commit Message

Ritesh Harjani (IBM) Oct. 11, 2024, 3 p.m. UTC

We anyway don't use any return values from fadump_cma_init(). Since
fadump_reserve_mem() from where fadump_cma_init() gets called today,
already has the required checks.
This patch makes this function return type as void. Let's also handle
extra cases like return if fadump_supported is false or dump_active, so
that in later patches we can call fadump_cma_init() separately from
setup_arch().

Acked-by: Hari Bathini <[e-mail]>
Signed-off-by: Ritesh Harjani (IBM) <[e-mail]>
---
v2 -> v3: Separated the series into 2 as discussed in v2.
[v2]: https://lore.kernel.org/linuxppc-dev/[e-mail]/

 arch/powerpc/kernel/fadump.c | 23 +++++++++--------------
 1 file changed, 9 insertions(+), 14 deletions(-)

--
2.46.0

Comments

Madhavan Srinivasan Oct. 14, 2024, 10:24 a.m. UTC | #1

On 10/11/24 8:30 PM, Ritesh Harjani (IBM) wrote:
> We anyway don't use any return values from fadump_cma_init(). Since
> fadump_reserve_mem() from where fadump_cma_init() gets called today,
> already has the required checks.
> This patch makes this function return type as void. Let's also handle
> extra cases like return if fadump_supported is false or dump_active, so
> that in later patches we can call fadump_cma_init() separately from
> setup_arch().

Usually patches to this file are posted with title format of

powerpc/fadump:<>


> 
> Acked-by: Hari Bathini <[e-mail]>
> Signed-off-by: Ritesh Harjani (IBM) <[e-mail]>
> ---
> v2 -> v3: Separated the series into 2 as discussed in v2.
> [v2]: https://lore.kernel.org/linuxppc-dev/[e-mail]/
> 
>  arch/powerpc/kernel/fadump.c | 23 +++++++++--------------
>  1 file changed, 9 insertions(+), 14 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
> index a612e7513a4f..162327d66982 100644
> --- a/arch/powerpc/kernel/fadump.c
> +++ b/arch/powerpc/kernel/fadump.c
> @@ -78,27 +78,23 @@ static struct cma *fadump_cma;
>   * But for some reason even if it fails we still have the memory reservation
>   * with us and we can still continue doing fadump.
>   */
> -static int __init fadump_cma_init(void)
> +static void __init fadump_cma_init(void)
>  {
>  	unsigned long long base, size;
>  	int rc;
> 
> -	if (!fw_dump.fadump_enabled)
> -		return 0;
> -
> +	if (!fw_dump.fadump_supported || !fw_dump.fadump_enabled ||
> +			fw_dump.dump_active)
> +		return;

Is these checks even needed here? fadump_reserve_mem() checked for all
these already, also dont see any other caller for fadump_cma_init(). 


>  	/*
>  	 * Do not use CMA if user has provided fadump=nocma kernel parameter.
> -	 * Return 1 to continue with fadump old behaviour.
>  	 */
> -	if (fw_dump.nocma)
> -		return 1;
> +	if (fw_dump.nocma || !fw_dump.boot_memory_size)
> +		return;
> 
>  	base = fw_dump.reserve_dump_area_start;
>  	size = fw_dump.boot_memory_size;
> 
> -	if (!size)
> -		return 0;

So this is the only place where we return 0, which in turn will make the
"ret" in fadump_reserve_mem() as zero forcing to call reserve_crashkernel()
in early_init_devtree().

we are removing it, becos we know "size" here will never be zero?


> -
>  	rc = cma_init_reserved_mem(base, size, 0, "fadump_cma", &fadump_cma);
>  	if (rc) {
>  		pr_err("Failed to init cma area for firmware-assisted dump,%d\n", rc);
> @@ -108,7 +104,7 @@ static int __init fadump_cma_init(void)
>  		 * blocked from production system usage.  Hence return 1,
>  		 * so that we can continue with fadump.
>  		 */
> -		return 1;
> +		return;
>  	}
> 
>  	/*
> @@ -125,10 +121,9 @@ static int __init fadump_cma_init(void)
>  		cma_get_size(fadump_cma),
>  		(unsigned long)cma_get_base(fadump_cma) >> 20,
>  		fw_dump.reserve_dump_area_size);
> -	return 1;
>  }
>  #else
> -static int __init fadump_cma_init(void) { return 1; }
> +static void __init fadump_cma_init(void) { }
>  #endif /* CONFIG_CMA */
> 
>  /*
> @@ -638,7 +633,7 @@ int __init fadump_reserve_mem(void)
>  		pr_info("Reserved %lldMB of memory at %#016llx (System RAM: %lldMB)\n",
>  			(size >> 20), base, (memblock_phys_mem_size() >> 20));
> 
> -		ret = fadump_cma_init();
> +		fadump_cma_init();
>  	}
> 
>  	return ret;
> --
> 2.46.0
>

Ritesh Harjani (IBM) Oct. 14, 2024, 11:24 a.m. UTC | #2

Madhavan Srinivasan <[e-mail]> writes:

> On 10/11/24 8:30 PM, Ritesh Harjani (IBM) wrote:
>> We anyway don't use any return values from fadump_cma_init(). Since
>> fadump_reserve_mem() from where fadump_cma_init() gets called today,
>> already has the required checks.
>> This patch makes this function return type as void. Let's also handle
>> extra cases like return if fadump_supported is false or dump_active, so
>> that in later patches we can call fadump_cma_init() separately from
>> setup_arch().
>
> Usually patches to this file are posted with title format of
>
> powerpc/fadump:<>

yes. I guess it is good to do it that way (I might have missed it)
Although commit history of oldest few patches to fadump shows..

ebaeb5ae2437 fadump: Convert firmware-assisted cpu state dump data into elf notes.
2df173d9e85d fadump: Initialize elfcore header and add PT_LOAD program headers.
3ccc00a7e04f fadump: Register for firmware assisted dump.
eb39c8803d0e fadump: Reserve the memory for firmware assisted dump.

>
>
>> 
>> Acked-by: Hari Bathini <[e-mail]>
>> Signed-off-by: Ritesh Harjani (IBM) <[e-mail]>
>> ---
>> v2 -> v3: Separated the series into 2 as discussed in v2.
>> [v2]: https://lore.kernel.org/linuxppc-dev/[e-mail]/
>> 
>>  arch/powerpc/kernel/fadump.c | 23 +++++++++--------------
>>  1 file changed, 9 insertions(+), 14 deletions(-)
>> 
>> diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
>> index a612e7513a4f..162327d66982 100644
>> --- a/arch/powerpc/kernel/fadump.c
>> +++ b/arch/powerpc/kernel/fadump.c
>> @@ -78,27 +78,23 @@ static struct cma *fadump_cma;
>>   * But for some reason even if it fails we still have the memory reservation
>>   * with us and we can still continue doing fadump.
>>   */
>> -static int __init fadump_cma_init(void)
>> +static void __init fadump_cma_init(void)
>>  {
>>  	unsigned long long base, size;
>>  	int rc;
>> 
>> -	if (!fw_dump.fadump_enabled)
>> -		return 0;
>> -
>> +	if (!fw_dump.fadump_supported || !fw_dump.fadump_enabled ||
>> +			fw_dump.dump_active)
>> +		return;
>
> Is these checks even needed here? fadump_reserve_mem() checked for all
> these already, also dont see any other caller for fadump_cma_init(). 
>
>

In the next patch we will move fadump_cma_init() call from within
fadump_reserve_mem() to setup_arch(). Hence we need these extra checks
in fadump_cma_init() as well. I mentioned the same in the commit msg of
this patch too.

>>  	/*
>>  	 * Do not use CMA if user has provided fadump=nocma kernel parameter.
>> -	 * Return 1 to continue with fadump old behaviour.
>>  	 */
>> -	if (fw_dump.nocma)
>> -		return 1;
>> +	if (fw_dump.nocma || !fw_dump.boot_memory_size)
>> +		return;
>> 
>>  	base = fw_dump.reserve_dump_area_start;
>>  	size = fw_dump.boot_memory_size;
>> 
>> -	if (!size)
>> -		return 0;
>
> So this is the only place where we return 0, which in turn will make the
> "ret" in fadump_reserve_mem() as zero forcing to call reserve_crashkernel()
> in early_init_devtree().
>
> we are removing it, becos we know "size" here will never be zero?
>
>

yes. Because we already check if boot_memory_size is less than
bootmem_min in fadump_reserve_mem(). If it is less, then we fail and
disable fadump (fadump_enabled = 0).

So then there is no need to check for !boot_memory_size in here.

fadump_reseve_mem( ) {
<...>
	if (!fw_dump.dump_active) {
		fw_dump.boot_memory_size =
			PAGE_ALIGN(fadump_calculate_reserve_size());

		bootmem_min = fw_dump.ops->fadump_get_bootmem_min();
		if (fw_dump.boot_memory_size < bootmem_min) {
			pr_err("Can't enable fadump with boot memory size (0x%lx) less than 0x%llx\n",
			       fw_dump.boot_memory_size, bootmem_min);
			goto error_out;
		}
    <...>    
    }
<...>
error_out:
	fw_dump.fadump_enabled = 0;
	fw_dump.reserve_dump_area_size = 0;
	return 0;
}


Thanks for the review!
-ritesh

Madhavan Srinivasan Oct. 14, 2024, 12:21 p.m. UTC | #3

On 10/14/24 4:54 PM, Ritesh Harjani (IBM) wrote:
> Madhavan Srinivasan <[e-mail]> writes:
> 
>> On 10/11/24 8:30 PM, Ritesh Harjani (IBM) wrote:
>>> We anyway don't use any return values from fadump_cma_init(). Since
>>> fadump_reserve_mem() from where fadump_cma_init() gets called today,
>>> already has the required checks.
>>> This patch makes this function return type as void. Let's also handle
>>> extra cases like return if fadump_supported is false or dump_active, so
>>> that in later patches we can call fadump_cma_init() separately from
>>> setup_arch().
>>
>> Usually patches to this file are posted with title format of
>>
>> powerpc/fadump:<>
> 
> yes. I guess it is good to do it that way (I might have missed it)
> Although commit history of oldest few patches to fadump shows..
> 
> ebaeb5ae2437 fadump: Convert firmware-assisted cpu state dump data into elf notes.
> 2df173d9e85d fadump: Initialize elfcore header and add PT_LOAD program headers.
> 3ccc00a7e04f fadump: Register for firmware assisted dump.
> eb39c8803d0e fadump: Reserve the memory for firmware assisted dump.
> 
>>
>>
>>>
>>> Acked-by: Hari Bathini <[e-mail]>
>>> Signed-off-by: Ritesh Harjani (IBM) <[e-mail]>
>>> ---
>>> v2 -> v3: Separated the series into 2 as discussed in v2.
>>> [v2]: https://lore.kernel.org/linuxppc-dev/[e-mail]/
>>>
>>>  arch/powerpc/kernel/fadump.c | 23 +++++++++--------------
>>>  1 file changed, 9 insertions(+), 14 deletions(-)
>>>
>>> diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
>>> index a612e7513a4f..162327d66982 100644
>>> --- a/arch/powerpc/kernel/fadump.c
>>> +++ b/arch/powerpc/kernel/fadump.c
>>> @@ -78,27 +78,23 @@ static struct cma *fadump_cma;
>>>   * But for some reason even if it fails we still have the memory reservation
>>>   * with us and we can still continue doing fadump.
>>>   */
>>> -static int __init fadump_cma_init(void)
>>> +static void __init fadump_cma_init(void)
>>>  {
>>>  	unsigned long long base, size;
>>>  	int rc;
>>>
>>> -	if (!fw_dump.fadump_enabled)
>>> -		return 0;
>>> -
>>> +	if (!fw_dump.fadump_supported || !fw_dump.fadump_enabled ||
>>> +			fw_dump.dump_active)
>>> +		return;
>>
>> Is these checks even needed here? fadump_reserve_mem() checked for all
>> these already, also dont see any other caller for fadump_cma_init(). 
>>
>>
> 
> In the next patch we will move fadump_cma_init() call from within
> fadump_reserve_mem() to setup_arch(). Hence we need these extra checks
> in fadump_cma_init() as well. I mentioned the same in the commit msg of
> this patch too.
> 

yes, just saw that when looking at the patch 3, sorry for the noise.


>>>  	/*
>>>  	 * Do not use CMA if user has provided fadump=nocma kernel parameter.
>>> -	 * Return 1 to continue with fadump old behaviour.
>>>  	 */
>>> -	if (fw_dump.nocma)
>>> -		return 1;
>>> +	if (fw_dump.nocma || !fw_dump.boot_memory_size)
>>> +		return;
>>>
>>>  	base = fw_dump.reserve_dump_area_start;
>>>  	size = fw_dump.boot_memory_size;
>>>
>>> -	if (!size)
>>> -		return 0;
>>
>> So this is the only place where we return 0, which in turn will make the
>> "ret" in fadump_reserve_mem() as zero forcing to call reserve_crashkernel()
>> in early_init_devtree().
>>
>> we are removing it, becos we know "size" here will never be zero?
>>
>>
> 
> yes. Because we already check if boot_memory_size is less than
> bootmem_min in fadump_reserve_mem(). If it is less, then we fail and
> disable fadump (fadump_enabled = 0).
>

Thanks for the clarification.


 
> So then there is no need to check for !boot_memory_size in here.
> 
> fadump_reseve_mem( ) {
> <...>
> 	if (!fw_dump.dump_active) {
> 		fw_dump.boot_memory_size =
> 			PAGE_ALIGN(fadump_calculate_reserve_size());
> 
> 		bootmem_min = fw_dump.ops->fadump_get_bootmem_min();
> 		if (fw_dump.boot_memory_size < bootmem_min) {
> 			pr_err("Can't enable fadump with boot memory size (0x%lx) less than 0x%llx\n",
> 			       fw_dump.boot_memory_size, bootmem_min);
> 			goto error_out;
> 		}
>     <...>    
>     }
> <...>
> error_out:
> 	fw_dump.fadump_enabled = 0;
> 	fw_dump.reserve_dump_area_size = 0;
> 	return 0;
> }
> 
> 
> Thanks for the review!
> -ritesh

Madhavan Srinivasan Oct. 18, 2024, 2:54 p.m. UTC | #4

On 10/14/24 4:54 PM, Ritesh Harjani (IBM) wrote:
> Madhavan Srinivasan <[e-mail]> writes:
> 
>> On 10/11/24 8:30 PM, Ritesh Harjani (IBM) wrote:
>>> We anyway don't use any return values from fadump_cma_init(). Since
>>> fadump_reserve_mem() from where fadump_cma_init() gets called today,
>>> already has the required checks.
>>> This patch makes this function return type as void. Let's also handle
>>> extra cases like return if fadump_supported is false or dump_active, so
>>> that in later patches we can call fadump_cma_init() separately from
>>> setup_arch().
>>
>> Usually patches to this file are posted with title format of
>>
>> powerpc/fadump:<>
> 
> yes. I guess it is good to do it that way (I might have missed it)
> Although commit history of oldest few patches to fadump shows..
> 
> ebaeb5ae2437 fadump: Convert firmware-assisted cpu state dump data into elf notes.
> 2df173d9e85d fadump: Initialize elfcore header and add PT_LOAD program headers.
> 3ccc00a7e04f fadump: Register for firmware assisted dump.
> eb39c8803d0e fadump: Reserve the memory for firmware assisted dump.
> 
>>

Patchset looks fine to me. 

Reviewed-by: Madhavan Srinivasan <[e-mail]> for the series.


>>
>>>
>>> Acked-by: Hari Bathini <[e-mail]>
>>> Signed-off-by: Ritesh Harjani (IBM) <[e-mail]>
>>> ---
>>> v2 -> v3: Separated the series into 2 as discussed in v2.
>>> [v2]: https://lore.kernel.org/linuxppc-dev/[e-mail]/
>>>
>>>  arch/powerpc/kernel/fadump.c | 23 +++++++++--------------
>>>  1 file changed, 9 insertions(+), 14 deletions(-)
>>>
>>> diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
>>> index a612e7513a4f..162327d66982 100644
>>> --- a/arch/powerpc/kernel/fadump.c
>>> +++ b/arch/powerpc/kernel/fadump.c
>>> @@ -78,27 +78,23 @@ static struct cma *fadump_cma;
>>>   * But for some reason even if it fails we still have the memory reservation
>>>   * with us and we can still continue doing fadump.
>>>   */
>>> -static int __init fadump_cma_init(void)
>>> +static void __init fadump_cma_init(void)
>>>  {
>>>  	unsigned long long base, size;
>>>  	int rc;
>>>
>>> -	if (!fw_dump.fadump_enabled)
>>> -		return 0;
>>> -
>>> +	if (!fw_dump.fadump_supported || !fw_dump.fadump_enabled ||
>>> +			fw_dump.dump_active)
>>> +		return;
>>
>> Is these checks even needed here? fadump_reserve_mem() checked for all
>> these already, also dont see any other caller for fadump_cma_init(). 
>>
>>
> 
> In the next patch we will move fadump_cma_init() call from within
> fadump_reserve_mem() to setup_arch(). Hence we need these extra checks
> in fadump_cma_init() as well. I mentioned the same in the commit msg of
> this patch too.
> 
>>>  	/*
>>>  	 * Do not use CMA if user has provided fadump=nocma kernel parameter.
>>> -	 * Return 1 to continue with fadump old behaviour.
>>>  	 */
>>> -	if (fw_dump.nocma)
>>> -		return 1;
>>> +	if (fw_dump.nocma || !fw_dump.boot_memory_size)
>>> +		return;
>>>
>>>  	base = fw_dump.reserve_dump_area_start;
>>>  	size = fw_dump.boot_memory_size;
>>>
>>> -	if (!size)
>>> -		return 0;
>>
>> So this is the only place where we return 0, which in turn will make the
>> "ret" in fadump_reserve_mem() as zero forcing to call reserve_crashkernel()
>> in early_init_devtree().
>>
>> we are removing it, becos we know "size" here will never be zero?
>>
>>
> 
> yes. Because we already check if boot_memory_size is less than
> bootmem_min in fadump_reserve_mem(). If it is less, then we fail and
> disable fadump (fadump_enabled = 0).
> 
> So then there is no need to check for !boot_memory_size in here.
> 
> fadump_reseve_mem( ) {
> <...>
> 	if (!fw_dump.dump_active) {
> 		fw_dump.boot_memory_size =
> 			PAGE_ALIGN(fadump_calculate_reserve_size());
> 
> 		bootmem_min = fw_dump.ops->fadump_get_bootmem_min();
> 		if (fw_dump.boot_memory_size < bootmem_min) {
> 			pr_err("Can't enable fadump with boot memory size (0x%lx) less than 0x%llx\n",
> 			       fw_dump.boot_memory_size, bootmem_min);
> 			goto error_out;
> 		}
>     <...>    
>     }
> <...>
> error_out:
> 	fw_dump.fadump_enabled = 0;
> 	fw_dump.reserve_dump_area_size = 0;
> 	return 0;
> }
> 
> 
> Thanks for the review!
> -ritesh

Ritesh Harjani (IBM) Oct. 18, 2024, 4:04 p.m. UTC | #5

Madhavan Srinivasan <[e-mail]> writes:

>
> Patchset looks fine to me. 
>
> Reviewed-by: Madhavan Srinivasan <[e-mail]> for the series.
>

Thanks Maddy for the reviews! 
I will spin PATCH v4 with these minor suggested changes (No code changes)

-ritesh

Patch

diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index a612e7513a4f..162327d66982 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -78,27 +78,23 @@  static struct cma *fadump_cma;
  * But for some reason even if it fails we still have the memory reservation
  * with us and we can still continue doing fadump.
  */
-static int __init fadump_cma_init(void)
+static void __init fadump_cma_init(void)
 {
 	unsigned long long base, size;
 	int rc;

-	if (!fw_dump.fadump_enabled)
-		return 0;
-
+	if (!fw_dump.fadump_supported || !fw_dump.fadump_enabled ||
+			fw_dump.dump_active)
+		return;
 	/*
 	 * Do not use CMA if user has provided fadump=nocma kernel parameter.
-	 * Return 1 to continue with fadump old behaviour.
 	 */
-	if (fw_dump.nocma)
-		return 1;
+	if (fw_dump.nocma || !fw_dump.boot_memory_size)
+		return;

 	base = fw_dump.reserve_dump_area_start;
 	size = fw_dump.boot_memory_size;

-	if (!size)
-		return 0;
-
 	rc = cma_init_reserved_mem(base, size, 0, "fadump_cma", &fadump_cma);
 	if (rc) {
 		pr_err("Failed to init cma area for firmware-assisted dump,%d\n", rc);
@@ -108,7 +104,7 @@  static int __init fadump_cma_init(void)
 		 * blocked from production system usage.  Hence return 1,
 		 * so that we can continue with fadump.
 		 */
-		return 1;
+		return;
 	}

 	/*
@@ -125,10 +121,9 @@  static int __init fadump_cma_init(void)
 		cma_get_size(fadump_cma),
 		(unsigned long)cma_get_base(fadump_cma) >> 20,
 		fw_dump.reserve_dump_area_size);
-	return 1;
 }
 #else
-static int __init fadump_cma_init(void) { return 1; }
+static void __init fadump_cma_init(void) { }
 #endif /* CONFIG_CMA */

 /*
@@ -638,7 +633,7 @@  int __init fadump_reserve_mem(void)
 		pr_info("Reserved %lldMB of memory at %#016llx (System RAM: %lldMB)\n",
 			(size >> 20), base, (memblock_phys_mem_size() >> 20));

-		ret = fadump_cma_init();
+		fadump_cma_init();
 	}

 	return ret;