From: Paul Mackerras Date: Fri, 12 Jun 2009 21:10:05 +0000 (+0000) Subject: lib: Provide generic atomic64_t implementation X-Git-Tag: v2.6.31-rc1~314^2~16 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=09d4e0edd4614e787393acc582ac701c6ec3565b;p=pandora-kernel.git 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 --- Reading git-diff-tree failed