Re: [PATCH 3/6] powerpc: fadump: use lock guard for mutex

[Shrikanth Hegde]

On 3/14/25 13:52, Peter Zijlstra wrote:

Thanks Peter for taking a look.


On Fri, Mar 14, 2025 at 11:15:41AM +0530, Shrikanth Hegde wrote:

use guard(mutex) for scope based resource management of mutex.
This would make the code simpler and easier to maintain.

More details on lock guards can be found at
https://lore.kernel.org/all/20230612093537.614161...@infradead.org/T/#u

Signed-off-by: Shrikanth Hegde 
---
  arch/powerpc/kernel/fadump.c | 6 ++
  1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index 4b371c738213..5fd2c546fd8c 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -1374,15 +1374,13 @@ static void fadump_free_elfcorehdr_buf(void)
  
  static void fadump_invalidate_release_mem(void)

  {
-   mutex_lock(&fadump_mutex);
+   guard(mutex)(&fadump_mutex);
+
if (!fw_dump.dump_active) {
-   mutex_unlock(&fadump_mutex);
return;
}
  
  	fadump_cleanup();

-   mutex_unlock(&fadump_mutex);
-


This will result in running the below functions with the mutex held.


fadump_free_elfcorehdr_buf();
fadump_release_memory(fw_dump.boot_mem_top, memblock_end_of_DRAM());
fadump_free_cpu_notes_buf();




Ok. Got it, since the variable is still in scope unlock wont be called.
So, will use scoped_guard as you suggested below in v2.



The equivalent transformation for the above code would look like:

static void fadump_invalidate_release_mem(void)
{
scoped_guard (mutex, &fadump_mutex) {
if (!fw_dump.dump_active)
return;

fadump_cleanup();
}

fadump_free_elfcorehdr_buf();
...


ok.

Re: [PATCH 3/6] powerpc: fadump: use lock guard for mutex

[Peter Zijlstra]

On Fri, Mar 14, 2025 at 11:15:41AM +0530, Shrikanth Hegde wrote:
> use guard(mutex) for scope based resource management of mutex.
> This would make the code simpler and easier to maintain.
> 
> More details on lock guards can be found at
> https://lore.kernel.org/all/20230612093537.614161...@infradead.org/T/#u
> 
> Signed-off-by: Shrikanth Hegde 
> ---
>  arch/powerpc/kernel/fadump.c | 6 ++
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
> index 4b371c738213..5fd2c546fd8c 100644
> --- a/arch/powerpc/kernel/fadump.c
> +++ b/arch/powerpc/kernel/fadump.c
> @@ -1374,15 +1374,13 @@ static void fadump_free_elfcorehdr_buf(void)
>  
>  static void fadump_invalidate_release_mem(void)
>  {
> - mutex_lock(&fadump_mutex);
> + guard(mutex)(&fadump_mutex);
> +
>   if (!fw_dump.dump_active) {
> - mutex_unlock(&fadump_mutex);
>   return;
>   }
>  
>   fadump_cleanup();
> - mutex_unlock(&fadump_mutex);
> -

This will result in running the below functions with the mutex held.

>   fadump_free_elfcorehdr_buf();
>   fadump_release_memory(fw_dump.boot_mem_top, memblock_end_of_DRAM());
>   fadump_free_cpu_notes_buf();


The equivalent transformation for the above code would look like:

static void fadump_invalidate_release_mem(void)
{
scoped_guard (mutex, &fadump_mutex) {
if (!fw_dump.dump_active)
return;

fadump_cleanup();
}

fadump_free_elfcorehdr_buf();
...