From 3cb4f9fa0c5f3ded9f70f85b70ee6d429834f911 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 16 Oct 2007 23:25:42 -0700 Subject: lib: percpu_counter_sub Hugh spotted that some code does: percpu_counter_add(&counter, -unsignedlong) which, when the amount argument is of type s32, sort-of works thanks to two's-complement. However when we'd change the type to s64 this breaks on 32bit machines, because the promotion rules zero extend the unsigned number. Provide percpu_counter_sub() to hide the s64 cast. That is: percpu_counter_sub(&counter, foo) is equal to: percpu_counter_add(&counter, -(s64)foo); Signed-off-by: Peter Zijlstra Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/percpu_counter.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include/linux') diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h index b84fc8667de..438a170187e 100644 --- a/include/linux/percpu_counter.h +++ b/include/linux/percpu_counter.h @@ -105,4 +105,9 @@ static inline void percpu_counter_dec(struct percpu_counter *fbc) percpu_counter_add(fbc, -1); } +static inline void percpu_counter_sub(struct percpu_counter *fbc, s64 amount) +{ + percpu_counter_add(fbc, -amount); +} + #endif /* _LINUX_PERCPU_COUNTER_H */ -- cgit v1.2.3