Re: [PATCH] cxl/hdm: fix a warning in devm_remove_action()

[Ira Weiny]

Sungwoo Kim wrote:
> In the following race scenario, devm_remove_action() can be called
> before devm_add_action(), triggering a warning because there is no
> action to remove.
> 
> To fix this, extend a critical section to embrace both
> __cxl_dpa_reserve() and devm_add_action().
> 
> task 1:
> cxl_dpa_alloc()
>   __cxl_dpa_reserve()    ...(1)
>   devm_add_action()      ...(4)
> 
> task 2:
> cxl_dpa_free()
>   guard()
>   if (!cxled->dpa_res)   ...(2) pass, due to (1)
>     return 0;
>   devm_cxl_dpa_release()
>     devm_remove_action()  ...(3) warning, no action is added yet
> 
> Warning log:
> 

[snip]

> 
> Fixes: cf880423b6a0 ("cxl/hdm: Add support for allocating DPA to an endpoint decoder")
> Fixes: 9c57cde0dcbd ("cxl/hdm: Enumerate allocated DPA")
> Signed-off-by: Sungwoo Kim <iam@xxxxxxxxxxxx>

Reviewed-by: Ira Weiny <ira.weiny@xxxxxxxxx>

[snip]