diff options
author | John Hubbard <jhubbard@nvidia.com> | 2021-09-02 23:53:54 +0200 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-09-03 18:58:11 +0200 |
commit | 9857a17f206ff374aea78bccfb687f145368be2e (patch) | |
tree | f1a43556c3df629a5343f3078d212d2dcf9bbad3 /mm/gup.c | |
parent | mm/gup: small refactoring: simplify try_grab_page() (diff) | |
download | linux-9857a17f206ff374aea78bccfb687f145368be2e.tar.xz linux-9857a17f206ff374aea78bccfb687f145368be2e.zip |
mm/gup: remove try_get_page(), call try_get_compound_head() directly
try_get_page() is very similar to try_get_compound_head(), and in fact
try_get_page() has fallen a little behind in terms of maintenance:
try_get_compound_head() handles speculative page references more
thoroughly.
There are only two try_get_page() callsites, so just call
try_get_compound_head() directly from those, and remove try_get_page()
entirely.
Also, seeing as how this changes try_get_compound_head() into a non-static
function, provide some kerneldoc documentation for it.
Link: https://lkml.kernel.org/r/20210813044133.1536842-4-jhubbard@nvidia.com
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/gup.c')
-rw-r--r-- | mm/gup.c | 21 |
1 files changed, 17 insertions, 4 deletions
@@ -62,11 +62,24 @@ static void put_page_refs(struct page *page, int refs) put_page(page); } -/* - * Return the compound head page with ref appropriately incremented, - * or NULL if that failed. +/** + * try_get_compound_head() - return the compound head page with refcount + * appropriately incremented, or NULL if that failed. + * + * This handles potential refcount overflow correctly. It also works correctly + * for various lockless get_user_pages()-related callers, due to the use of + * page_cache_add_speculative(). + * + * Even though the name includes "compound_head", this function is still + * appropriate for callers that have a non-compound @page to get. + * + * @page: pointer to page to be gotten + * @refs: the value to add to the page's refcount + * + * Return: head page (with refcount appropriately incremented) for success, or + * NULL upon failure. */ -static inline struct page *try_get_compound_head(struct page *page, int refs) +struct page *try_get_compound_head(struct page *page, int refs) { struct page *head = compound_head(page); |