tasklet: Remove tasklet_kill_immediate

Ever since RCU was converted to softirq, it has no users.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Link: https://lore.kernel.org/r/20210306213658.12862-1-dave@stgolabs.net

include/linux/interrupt.h

@@ -716,7 +716,6 @@ static inline void tasklet_enable(struct tasklet_struct *t)
 }
 
 extern void tasklet_kill(struct tasklet_struct *t);
-extern void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu);
 extern void tasklet_init(struct tasklet_struct *t,
 			 void (*func)(unsigned long), unsigned long data);
 extern void tasklet_setup(struct tasklet_struct *t,

kernel/softirq.c

@@ -658,38 +658,6 @@ static void run_ksoftirqd(unsigned int cpu)
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
-/*
- * tasklet_kill_immediate is called to remove a tasklet which can already be
- * scheduled for execution on @cpu.
- *
- * Unlike tasklet_kill, this function removes the tasklet
- * _immediately_, even if the tasklet is in TASKLET_STATE_SCHED state.
- *
- * When this function is called, @cpu must be in the CPU_DEAD state.
- */
-void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu)
-{
-	struct tasklet_struct **i;
-
-	BUG_ON(cpu_online(cpu));
-	BUG_ON(test_bit(TASKLET_STATE_RUN, &t->state));
-
-	if (!test_bit(TASKLET_STATE_SCHED, &t->state))
-		return;
-
-	/* CPU is dead, so no lock needed. */
-	for (i = &per_cpu(tasklet_vec, cpu).head; *i; i = &(*i)->next) {
-		if (*i == t) {
-			*i = t->next;
-			/* If this was the tail element, move the tail ptr */
-			if (*i == NULL)
-				per_cpu(tasklet_vec, cpu).tail = i;
-			return;
-		}
-	}
-	BUG();
-}
-
 static int takeover_tasklets(unsigned int cpu)
 {
 	/* CPU is dead, so no lock needed. */