Re: [PATCH] PCI: endpoint: Use 'bitmap_zalloc()' when applicable

[Christophe JAILLET]

Le 06/11/2021 à 23:01, Krzysztof Wilczyński a écrit :
> 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.

Hi,

mostly a mater of taste.
On another similar patch I got the answer in [1] :).

'mem' is kzalloc'ed, so in case of failure, here we are just replacing 
NULL by NULL.

Let me know the preferred style here and if I should send a V2.

CJ

[1]; https://lore.kernel.org/kernel-janitors/20211028164437.GA4045120@p14s/

> [...]
> > @@ -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@xxxxxxxxx>
>
> 	Krzysztof