From 09d4e0edd4614e787393acc582ac701c6ec3565b Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Fri, 12 Jun 2009 21:10:05 +0000 Subject: lib: Provide generic atomic64_t implementation Many processor architectures have no 64-bit atomic instructions, but we need atomic64_t in order to support the perf_counter subsystem. This adds an implementation of 64-bit atomic operations using hashed spinlocks to provide atomicity. For each atomic operation, the address of the atomic64_t variable is hashed to an index into an array of 16 spinlocks. That spinlock is taken (with interrupts disabled) around the operation, which can then be coded non-atomically within the lock. On UP, all the spinlock manipulation goes away and we simply disable interrupts around each operation. In fact gcc eliminates the whole atomic64_lock variable as well. Signed-off-by: Paul Mackerras Signed-off-by: Benjamin Herrenschmidt --- lib/Kconfig | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'lib/Kconfig') diff --git a/lib/Kconfig b/lib/Kconfig index 9960be04cbbe..bb1326d3839c 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -194,4 +194,10 @@ config DISABLE_OBSOLETE_CPUMASK_FUNCTIONS config NLATTR bool +# +# Generic 64-bit atomic support is selected if needed +# +config GENERIC_ATOMIC64 + bool + endmenu -- cgit v1.2.3