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authorPaul Mackerras <paulus@samba.org>2009-06-13 01:10:05 +0400
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2009-06-15 07:27:38 +0400
commit09d4e0edd4614e787393acc582ac701c6ec3565b (patch)
tree77f3b85e0f59a168ac78639e510ebcbd3791b3d2 /lib/Makefile
parent4c75f84f2c781beb230031234ed961d28771a764 (diff)
downloadlinux-09d4e0edd4614e787393acc582ac701c6ec3565b.tar.xz
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 <paulus@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'lib/Makefile')
-rw-r--r--lib/Makefile2
1 files changed, 2 insertions, 0 deletions
diff --git a/lib/Makefile b/lib/Makefile
index 34c5c0e6222e..8e9bcf9d3261 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -95,6 +95,8 @@ obj-$(CONFIG_DMA_API_DEBUG) += dma-debug.o
obj-$(CONFIG_GENERIC_CSUM) += checksum.o
+obj-$(CONFIG_GENERIC_ATOMIC64) += atomic64.o
+
hostprogs-y := gen_crc32table
clean-files := crc32table.h