- Close races with signals and other AST's being triggered while we are in

  the process of exiting the kernel.  The ast() function now loops as long
  as the PS_ASTPENDING or PS_NEEDRESCHED flags are set.  It returns with
  preemption disabled so that any further AST's that arrive via an
  interrupt will be delayed until the low-level MD code returns to user
  mode.
- Use u_int's to store the tick counts for profiling purposes so that we
  do not need sched_lock just to read p_sticks.  This also closes a
  problem where the call to addupc_task() could screw up the arithmetic
  due to non-atomic reads of p_sticks.
- Axe need_proftick(), aston(), astoff(), astpending(), need_resched(),
  clear_resched(), and resched_wanted() in favor of direct bit operations
  on p_sflag.
- Fix up locking with sched_lock some.  In addupc_intr(), use sched_lock
  to ensure pr_addr and pr_ticks are updated atomically with setting
  PS_OWEUPC.  In ast() we clear pr_ticks atomically with clearing
  PS_OWEUPC.  We also do not grab the lock just to test a flag.
- Simplify the handling of Giant in ast() slightly.

Reviewed by:	bde (mostly)

2 files changed, 2 insertions, 20 deletions

diff --git a/sys/alpha/alpha/trap.c b/sys/alpha/alpha/trap.c
index 2fdb2a2..423d4a7 100644
--- a/sys/alpha/alpha/trap.c
+++ b/sys/alpha/alpha/trap.c
@@ -259,7 +259,7 @@ trap(a0, a1, a2, entry, framep)
 	register struct proc *p;
 	register int i;
 	u_int64_t ucode;
-	u_quad_t sticks;
+	u_int sticks;
 	int user;
 #ifdef SMP
 	critical_t s;
@@ -289,9 +289,7 @@ trap(a0, a1, a2, entry, framep)
 	CTR5(KTR_TRAP, "%s trap: pid %d, (%lx, %lx, %lx)",
 	    user ? "user" : "kernel", p->p_pid, a0, a1, a2);
 	if (user)  {
-		mtx_lock_spin(&sched_lock);
 		sticks = p->p_sticks;
-		mtx_unlock_spin(&sched_lock);
 		p->p_frame = framep;
 	} else {
 		sticks = 0;		/* XXX bogus -Wuninitialized warning */
@@ -654,7 +652,7 @@ syscall(code, framep)
 	struct proc *p;
 	int error = 0;
 	u_int64_t opc;
-	u_quad_t sticks;
+	u_int sticks;
 	u_int64_t args[10];					/* XXX */
 	u_int hidden = 0, nargs;
 #ifdef SMP
@@ -685,9 +683,7 @@ syscall(code, framep)
 	cnt.v_syscall++;
 	p->p_frame = framep;
 	opc = framep->tf_regs[FRAME_PC] - 4;
-	mtx_lock_spin(&sched_lock);
 	sticks = p->p_sticks;
-	mtx_unlock_spin(&sched_lock);
 
 #ifdef DIAGNOSTIC
 	alpha_fpstate_check(p);
diff --git a/sys/alpha/include/cpu.h b/sys/alpha/include/cpu.h
index e901cb1..69ed2ea 100644
--- a/sys/alpha/include/cpu.h
+++ b/sys/alpha/include/cpu.h
@@ -70,20 +70,6 @@ struct clockframe {
 #define	CLKF_PC(framep)		TRAPF_PC(&(framep)->cf_tf)
 
 /*
- * Arrange to handle pending profiling ticks before returning to user mode.
- *
- * XXX this is now poorly named and implemented.  It used to handle only a
- * single tick and the PS_OWEUPC flag served as a counter.  Now there is a
- * counter in the proc table and flag isn't really necessary.
- */
-#define	need_proftick(p) do {						\
-	mtx_lock_spin(&sched_lock);					\
-	(p)->p_sflag |= PS_OWEUPC;					\
-	aston(p);							\
-	mtx_unlock_spin(&sched_lock);					\
-} while (0)
-
-/*
  * CTL_MACHDEP definitions.
  */
 #define	CPU_CONSDEV		1	/* dev_t: console terminal device */