linux-kernel - Re: [PATCH] PCI: endpoint: Use 'bitmap

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Date:   Sat, 6 Nov 2021 23:01:27 +0100
From:   Krzysztof Wilczyński <kw@...ux.com>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc:     kishon@...com, lorenzo.pieralisi@....com, bhelgaas@...gle.com,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] PCI: endpoint: Use 'bitmap_zalloc()' when applicable

Hi Christophe,

> 'mem->bitmap' is a bitmap. So use 'bitmap_zalloc()' to simplify code,
> improve the semantic and avoid some open-coded arithmetic in allocator
> arguments.
> 
> Also change the corresponding 'kfree()' into 'bitmap_free()' to keep
> consistency.

Thank you!

> Finally, while at it, axe the useless 'bitmap' variable and use
> 'mem->bitmap' directly.

Personally, I would keep the bitmap variable - this might be what Bjorn
would also prefer, as I believe he prefers not to store what is a "failed"
state of sorts in a target variable directly, if memory serves me right.

[...]
> @@ -49,10 +49,8 @@ int pci_epc_multi_mem_init(struct pci_epc *epc,
>  			   unsigned int num_windows)
>  {
>  	struct pci_epc_mem *mem = NULL;
> -	unsigned long *bitmap = NULL;
>  	unsigned int page_shift;
>  	size_t page_size;
> -	int bitmap_size;
>  	int pages;
>  	int ret;
>  	int i;
> @@ -72,7 +70,6 @@ int pci_epc_multi_mem_init(struct pci_epc *epc,
>  			page_size = PAGE_SIZE;
>  		page_shift = ilog2(page_size);
>  		pages = windows[i].size >> page_shift;
> -		bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);
>  
>  		mem = kzalloc(sizeof(*mem), GFP_KERNEL);
>  		if (!mem) {
> @@ -81,8 +78,8 @@ int pci_epc_multi_mem_init(struct pci_epc *epc,
>  			goto err_mem;
>  		}
>  
> -		bitmap = kzalloc(bitmap_size, GFP_KERNEL);
> -		if (!bitmap) {
> +		mem->bitmap = bitmap_zalloc(pages, GFP_KERNEL);
> +		if (!mem->bitmap) {
>  			ret = -ENOMEM;
>  			kfree(mem);
>  			i--;
> @@ -92,7 +89,6 @@ int pci_epc_multi_mem_init(struct pci_epc *epc,
>  		mem->window.phys_base = windows[i].phys_base;
>  		mem->window.size = windows[i].size;
>  		mem->window.page_size = page_size;
> -		mem->bitmap = bitmap;
>  		mem->pages = pages;
>  		mutex_init(&mem->lock);
>  		epc->windows[i] = mem;
> @@ -106,7 +102,7 @@ int pci_epc_multi_mem_init(struct pci_epc *epc,
>  err_mem:
>  	for (; i >= 0; i--) {
>  		mem = epc->windows[i];
> -		kfree(mem->bitmap);
> +		bitmap_free(mem->bitmap);
>  		kfree(mem);
>  	}
>  	kfree(epc->windows);
> @@ -145,7 +141,7 @@ void pci_epc_mem_exit(struct pci_epc *epc)
>  
>  	for (i = 0; i < epc->num_windows; i++) {
>  		mem = epc->windows[i];
> -		kfree(mem->bitmap);
> +		bitmap_free(mem->bitmap);
>  		kfree(mem);
>  	}
>  	kfree(epc->windows);

Thank you!

Reviewed-by: Krzysztof Wilczyński <kw@...ux.com>

	Krzysztof