Re: [PATCH 2/2] staging: media: atomisp: unify initialization flag usage in HMM

[Hans de Goede <hansg@kernel.org>]

Hi Abdelrahman,

On 7-Jul-25 16:09, Abdelrahman Fekry wrote:
> Previously, the initialization state of the `hmm_bo_device` was tracked
> in two places: a global `hmm_initialized` boolean in `hmm.c`, and a local
> integer `flag` in the `hmm_bo_device` struct. This was redundant and could
> lead to inconsistent state checks.
> 
> - Removes the global `hmm_initialized` variable and all checks against it.
> - Replaces the `int flag` in `struct hmm_bo_device` with a strongly-typed 
>  `enum hmm_bo_device_init_flag flag` (values: UNINITED = 0, INITED = 1).
> - Initializes `flag` to `HMM_BO_DEVICE_UNINITED` at declaration to 
>   ensure a well-defined starting state.
> - Removes a redundant `hmm_init()` call inside `__hmm_alloc()` since its
>   always called after hmm_init()
> 
> This change improves type safety, consistency, and readability when
> handling the HMM initialization state.
> 
> Signed-off-by: Abdelrahman Fekry <abdelrahmanfekry375@gmail.com>
> ---
>  .../staging/media/atomisp/include/hmm/hmm_bo.h   |  9 +++++++--
>  drivers/staging/media/atomisp/pci/hmm/hmm.c      | 16 ++++------------
>  2 files changed, 11 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/staging/media/atomisp/include/hmm/hmm_bo.h b/drivers/staging/media/atomisp/include/hmm/hmm_bo.h
> index e09ac29ac43d..155f9d89b365 100644
> --- a/drivers/staging/media/atomisp/include/hmm/hmm_bo.h
> +++ b/drivers/staging/media/atomisp/include/hmm/hmm_bo.h
> @@ -58,7 +58,10 @@
>  #define	ISP_VM_SIZE	(0x7FFFFFFF)	/* 2G address space */
>  #define	ISP_PTR_NULL	NULL
>  
> -#define	HMM_BO_DEVICE_INITED	0x1
> +enum hmm_bo_device_init_flag {
> +	HMM_BO_DEVICE_INITED	= 0x1,
> +	HMM_BO_DEVICE_UNINITED	= 0x2,
> +};
>  
>  enum hmm_bo_type {
>  	HMM_BO_PRIVATE,
> @@ -86,7 +89,9 @@ struct hmm_bo_device {
>  
>  	/* list lock is used to protect the entire_bo_list */
>  	spinlock_t	list_lock;
> -	int flag;
> +
> +	/* flag to indicate whether the bo device is inited or not */
> +	enum hmm_bo_device_init_flag flag;

Please just replace this with a "bool initialized"; data
member taking `true` and `false as values instead of
introducing a new type for this.

>  
>  	/* linked list for entire buffer object */
>  	struct list_head entire_bo_list;
> diff --git a/drivers/staging/media/atomisp/pci/hmm/hmm.c b/drivers/staging/media/atomisp/pci/hmm/hmm.c
> index c2ee9d2ec0d5..767a3a24f8e5 100644
> --- a/drivers/staging/media/atomisp/pci/hmm/hmm.c
> +++ b/drivers/staging/media/atomisp/pci/hmm/hmm.c
> @@ -24,9 +24,10 @@
>  #include "mmu/isp_mmu.h"
>  #include "mmu/sh_mmu_mrfld.h"
>  
> -struct hmm_bo_device bo_device;
> +struct hmm_bo_device bo_device = {
> +	.flag = HMM_BO_DEVICE_UNINITED,
> +};
>  static ia_css_ptr dummy_ptr = mmgr_EXCEPTION;
> -static bool hmm_initialized;
>  
>  int hmm_init(void)
>  {
> @@ -38,8 +39,6 @@ int hmm_init(void)
>  		dev_err(atomisp_dev, "hmm_bo_device_init failed.\n");
>  		return ret;
>  
> -	hmm_initialized = true;
> -
>  	/*
>  	 * As hmm use NULL to indicate invalid ISP virtual address,
>  	 * and ISP_VM_START is defined to 0 too, so we allocate
> @@ -62,7 +61,7 @@ void hmm_cleanup(void)
>  	dummy_ptr = 0;
>  
>  	hmm_bo_device_exit(&bo_device);
> -	hmm_initialized = false;
> +	bo_device.flag = HMM_BO_DEVICE_UNINITED;

This clearing of the flag / setting `initialized = false` belongs inside bo_exit()
not here.


>  }
>  
>  static ia_css_ptr __hmm_alloc(size_t bytes, enum hmm_bo_type type,
> @@ -72,13 +71,6 @@ static ia_css_ptr __hmm_alloc(size_t bytes, enum hmm_bo_type type,
>  	struct hmm_buffer_object *bo;
>  	int ret;
>  
> -	/*
> -	 * Check if we are initialized. In the ideal world we wouldn't need
> -	 * this but we can tackle it once the driver is a lot cleaner
> -	 */
> -
> -	if (!hmm_initialized)
> -		hmm_init();
>  	/* Get page number from size */
>  	pgnr = size_to_pgnr_ceil(bytes);
>  


Regards,

Hans