[PATCH] sched: cleanup context switch locking

Instead of requiring architecture code to interact with the scheduler's
locking implementation, provide a couple of defines that can be used by the
architecture to request runqueue unlocked context switches, and ask for
interrupts to be enabled over the context switch.

Also replaces the "switch_lock" used by these architectures with an oncpu
flag (note, not a potentially slow bitflag).  This eliminates one bus
locked memory operation when context switching, and simplifies the
task_running function.

Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 1 insertions, 9 deletions

diff --git a/include/asm-ia64/system.h b/include/asm-ia64/system.h
index 6f516e76d1f0..cd2cf76b2db1 100644
--- a/include/asm-ia64/system.h
+++ b/include/asm-ia64/system.h
@@ -183,8 +183,6 @@ do {								\
 
 #ifdef __KERNEL__
 
-#define prepare_to_switch()    do { } while(0)
-
 #ifdef CONFIG_IA32_SUPPORT
 # define IS_IA32_PROCESS(regs)  (ia64_psr(regs)->is != 0)
 #else
@@ -274,13 +272,7 @@ extern void ia64_load_extra (struct task_struct *task);
  * of that CPU which will not be released, because there we wait for the
  * tasklist_lock to become available.
  */
-#define prepare_arch_switch(rq, next)           \
-do {                                            \
-        spin_lock(&(next)->switch_lock);        \
-        spin_unlock(&(rq)->lock);               \
-} while (0)
-#define finish_arch_switch(rq, prev)    spin_unlock_irq(&(prev)->switch_lock)
-#define task_running(rq, p)             ((rq)->curr == (p) || spin_is_locked(&(p)->switch_lock))
+#define __ARCH_WANT_UNLOCKED_CTXSW
 
 #define ia64_platform_is(x) (strcmp(x, platform_name) == 0)