From: Andy Shevchenko Date: Tue, 6 May 2025 04:20:47 +0000 (-0700) Subject: locking/lockdep: Move hlock_equal() to the respective #ifdeffery X-Git-Tag: block-6.16-20250606~27^2~3 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=96ca1830e1219eda431702eb9a74225e8fe3ccc0;p=linux-block.git locking/lockdep: Move hlock_equal() to the respective #ifdeffery When hlock_equal() is unused, it prevents kernel builds with clang, `make W=1` and CONFIG_WERROR=y, CONFIG_LOCKDEP=y and CONFIG_LOCKDEP_SMALL=n: lockdep.c:2005:20: error: unused function 'hlock_equal' [-Werror,-Wunused-function] Fix this by moving the function to the respective existing ifdeffery for its the only user. See also: 6863f5643dd7 ("kbuild: allow Clang to find unused static inline functions for W=1 build") Fixes: 68e305678583 ("lockdep: Adjust check_redundant() for recursive read change") Signed-off-by: Andy Shevchenko Signed-off-by: Boqun Feng Signed-off-by: Ingo Molnar Cc: Bill Wendling Cc: Justin Stitt Cc: Nathan Chancellor Cc: Nick Desaulniers Cc: Peter Zijlstra Cc: Waiman Long Cc: Will Deacon Cc: llvm@lists.linux.dev Link: https://lore.kernel.org/r/20250506042049.50060-2-boqun.feng@gmail.com --- diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 58d78a33ac65..546e92827de4 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -1976,41 +1976,6 @@ print_circular_bug_header(struct lock_list *entry, unsigned int depth, print_circular_bug_entry(entry, depth); } -/* - * We are about to add A -> B into the dependency graph, and in __bfs() a - * strong dependency path A -> .. -> B is found: hlock_class equals - * entry->class. - * - * If A -> .. -> B can replace A -> B in any __bfs() search (means the former - * is _stronger_ than or equal to the latter), we consider A -> B as redundant. - * For example if A -> .. -> B is -(EN)-> (i.e. A -(E*)-> .. -(*N)-> B), and A - * -> B is -(ER)-> or -(EN)->, then we don't need to add A -> B into the - * dependency graph, as any strong path ..-> A -> B ->.. we can get with - * having dependency A -> B, we could already get a equivalent path ..-> A -> - * .. -> B -> .. with A -> .. -> B. Therefore A -> B is redundant. - * - * We need to make sure both the start and the end of A -> .. -> B is not - * weaker than A -> B. For the start part, please see the comment in - * check_redundant(). For the end part, we need: - * - * Either - * - * a) A -> B is -(*R)-> (everything is not weaker than that) - * - * or - * - * b) A -> .. -> B is -(*N)-> (nothing is stronger than this) - * - */ -static inline bool hlock_equal(struct lock_list *entry, void *data) -{ - struct held_lock *hlock = (struct held_lock *)data; - - return hlock_class(hlock) == entry->class && /* Found A -> .. -> B */ - (hlock->read == 2 || /* A -> B is -(*R)-> */ - !entry->only_xr); /* A -> .. -> B is -(*N)-> */ -} - /* * We are about to add B -> A into the dependency graph, and in __bfs() a * strong dependency path A -> .. -> B is found: hlock_class equals @@ -2915,6 +2880,41 @@ static inline bool usage_skip(struct lock_list *entry, void *mask) #endif /* CONFIG_TRACE_IRQFLAGS */ #ifdef CONFIG_LOCKDEP_SMALL +/* + * We are about to add A -> B into the dependency graph, and in __bfs() a + * strong dependency path A -> .. -> B is found: hlock_class equals + * entry->class. + * + * If A -> .. -> B can replace A -> B in any __bfs() search (means the former + * is _stronger_ than or equal to the latter), we consider A -> B as redundant. + * For example if A -> .. -> B is -(EN)-> (i.e. A -(E*)-> .. -(*N)-> B), and A + * -> B is -(ER)-> or -(EN)->, then we don't need to add A -> B into the + * dependency graph, as any strong path ..-> A -> B ->.. we can get with + * having dependency A -> B, we could already get a equivalent path ..-> A -> + * .. -> B -> .. with A -> .. -> B. Therefore A -> B is redundant. + * + * We need to make sure both the start and the end of A -> .. -> B is not + * weaker than A -> B. For the start part, please see the comment in + * check_redundant(). For the end part, we need: + * + * Either + * + * a) A -> B is -(*R)-> (everything is not weaker than that) + * + * or + * + * b) A -> .. -> B is -(*N)-> (nothing is stronger than this) + * + */ +static inline bool hlock_equal(struct lock_list *entry, void *data) +{ + struct held_lock *hlock = (struct held_lock *)data; + + return hlock_class(hlock) == entry->class && /* Found A -> .. -> B */ + (hlock->read == 2 || /* A -> B is -(*R)-> */ + !entry->only_xr); /* A -> .. -> B is -(*N)-> */ +} + /* * Check that the dependency graph starting at can lead to * or not. If it can, -> dependency is already