From 0fcf8ef4fdab8e5c91d1bce39c7fe6565974ffad Mon Sep 17 00:00:00 2001 From: Kairui Song Date: Wed, 17 Sep 2025 00:00:52 +0800 Subject: mm, swap: tidy up swap device and cluster info helpers swp_swap_info is the most commonly used helper for retrieving swap info. It has an internal check that may lead to a NULL return value, but almost none of its caller checks the return value, making the internal check pointless. In fact, most of these callers already ensured the entry is valid and never expect a NULL value. Tidy this up and improve the function names. If the caller can make sure the swap entry/type is valid and the device is pinned, use the new introduced __swap_entry_to_info/__swap_type_to_info instead. They have more debug sanity checks and lower overhead as they are inlined. Callers that may expect a NULL value should use swap_entry_to_info/swap_type_to_info instead. No feature change. The rearranged codes should have had no effect, or they should have been hitting NULL de-ref bugs already. Only some new sanity checks are added so potential issues may show up in debug build. The new helpers will be frequently used with swap table later when working with swap cache folios. A locked swap cache folio ensures the entries are valid and stable so these helpers are very helpful. Link: https://lkml.kernel.org/r/20250916160100.31545-8-ryncsn@gmail.com Signed-off-by: Kairui Song Acked-by: Chris Li Reviewed-by: Barry Song Acked-by: David Hildenbrand Suggested-by: Chris Li Cc: Baolin Wang Cc: Baoquan He Cc: "Huang, Ying" Cc: Hugh Dickins Cc: Johannes Weiner Cc: Kemeng Shi Cc: kernel test robot Cc: Lorenzo Stoakes Cc: Matthew Wilcox (Oracle) Cc: Nhat Pham Cc: Yosry Ahmed Cc: Zi Yan Cc: SeongJae Park Signed-off-by: Andrew Morton --- include/linux/swap.h | 6 ------ 1 file changed, 6 deletions(-) (limited to 'include/linux') diff --git a/include/linux/swap.h b/include/linux/swap.h index 78cc48a65512..762f8db0e811 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -479,7 +479,6 @@ extern sector_t swapdev_block(int, pgoff_t); extern int __swap_count(swp_entry_t entry); extern bool swap_entry_swapped(struct swap_info_struct *si, swp_entry_t entry); extern int swp_swapcount(swp_entry_t entry); -struct swap_info_struct *swp_swap_info(swp_entry_t entry); struct backing_dev_info; extern int init_swap_address_space(unsigned int type, unsigned long nr_pages); extern void exit_swap_address_space(unsigned int type); @@ -492,11 +491,6 @@ static inline void put_swap_device(struct swap_info_struct *si) } #else /* CONFIG_SWAP */ -static inline struct swap_info_struct *swp_swap_info(swp_entry_t entry) -{ - return NULL; -} - static inline struct swap_info_struct *get_swap_device(swp_entry_t entry) { return NULL; -- cgit v1.2.3