Commit 20b7fee7 authored by John Hubbard's avatar John Hubbard Committed by Linus Torvalds
Browse files

mm/gup: further simplify __gup_device_huge() 

Commit 6401c4eb ("mm: gup: fix potential pgmap refcnt leak in
__gup_device_huge()") simplified the return paths, but didn't go quite
far enough, as discussed in [1].

Remove the "ret" variable entirely, because there is enough information
already available to provide the return value.

[1] https://lore.kernel.org/r/CAHk-=wgQTRX=5SkCmS+zfmpqubGHGJvXX_HgnPG8JSpHKHBMeg@mail.gmail.com

Link: https://lkml.kernel.org/r/20210904004224.86391-1-jhubbard@nvidia.com


Signed-off-by: default avatarJohn Hubbard <jhubbard@nvidia.com>
Suggested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f8ee8909

mm/gup.c

+1 −4
Original line number Original line Diff line number Diff line
@@ -2228,7 +2228,6 @@ static int __gup_device_huge(unsigned long pfn, unsigned long addr, 
{

{

	int nr_start = *nr;

	int nr_start = *nr;

	struct dev_pagemap *pgmap = NULL;

	struct dev_pagemap *pgmap = NULL;

	int ret = 1;





	do {

	do {

		struct page *page = pfn_to_page(pfn);

		struct page *page = pfn_to_page(pfn);
@@ -2236,14 +2235,12 @@ static int __gup_device_huge(unsigned long pfn, unsigned long addr, 
		pgmap = get_dev_pagemap(pfn, pgmap);

		pgmap = get_dev_pagemap(pfn, pgmap);

		if (unlikely(!pgmap)) {

		if (unlikely(!pgmap)) {

			undo_dev_pagemap(nr, nr_start, flags, pages);

			undo_dev_pagemap(nr, nr_start, flags, pages);

			ret = 0;

			break;

			break;

		}

		}

		SetPageReferenced(page);

		SetPageReferenced(page);

		pages[*nr] = page;

		pages[*nr] = page;

		if (unlikely(!try_grab_page(page, flags))) {

		if (unlikely(!try_grab_page(page, flags))) {

			undo_dev_pagemap(nr, nr_start, flags, pages);

			undo_dev_pagemap(nr, nr_start, flags, pages);

			ret = 0;

			break;

			break;

		}

		}

		(*nr)++;

		(*nr)++;
@@ -2251,7 +2248,7 @@ static int __gup_device_huge(unsigned long pfn, unsigned long addr, 
	} while (addr += PAGE_SIZE, addr != end);

	} while (addr += PAGE_SIZE, addr != end);





	put_dev_pagemap(pgmap);

	put_dev_pagemap(pgmap);

	return ret;

	return addr == end;

}

}





static int __gup_device_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,

static int __gup_device_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,