tasklets: execute tasklets in the same order they were queued

[pandora-kernel.git] / kernel / softirq.c

diff --git a/kernel/softirq.c b/kernel/softirq.c
index 31e9f2a..3c44956 100644 (file)
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -356,7 +356,8 @@ void open_softirq(int nr, void (*action)(struct softirq_action*), void *data)
 /* Tasklets */
 struct tasklet_head
 {
-       struct tasklet_struct *list;
+       struct tasklet_struct *head;
+       struct tasklet_struct **tail;
 };
 
 /* Some compilers disobey section attribute on statics when not
@@ -369,8 +370,9 @@ void __tasklet_schedule(struct tasklet_struct *t)
        unsigned long flags;
 
        local_irq_save(flags);
-       t->next = __get_cpu_var(tasklet_vec).list;
-       __get_cpu_var(tasklet_vec).list = t;
+       t->next = NULL;
+       *__get_cpu_var(tasklet_vec).tail = t;
+       __get_cpu_var(tasklet_vec).tail = &(t->next);
        raise_softirq_irqoff(TASKLET_SOFTIRQ);
        local_irq_restore(flags);
 }
@@ -382,8 +384,9 @@ void __tasklet_hi_schedule(struct tasklet_struct *t)
        unsigned long flags;
 
        local_irq_save(flags);
-       t->next = __get_cpu_var(tasklet_hi_vec).list;
-       __get_cpu_var(tasklet_hi_vec).list = t;
+       t->next = NULL;
+       *__get_cpu_var(tasklet_hi_vec).tail = t;
+       __get_cpu_var(tasklet_hi_vec).tail = &(t->next);
        raise_softirq_irqoff(HI_SOFTIRQ);
        local_irq_restore(flags);
 }
@@ -395,8 +398,9 @@ static void tasklet_action(struct softirq_action *a)
        struct tasklet_struct *list;
 
        local_irq_disable();
-       list = __get_cpu_var(tasklet_vec).list;
-       __get_cpu_var(tasklet_vec).list = NULL;
+       list = __get_cpu_var(tasklet_vec).head;
+       __get_cpu_var(tasklet_vec).head = NULL;
+       __get_cpu_var(tasklet_vec).tail = &__get_cpu_var(tasklet_vec).head;
        local_irq_enable();
 
        while (list) {
@@ -416,8 +420,9 @@ static void tasklet_action(struct softirq_action *a)
                }
 
                local_irq_disable();
-               t->next = __get_cpu_var(tasklet_vec).list;
-               __get_cpu_var(tasklet_vec).list = t;
+               t->next = NULL;
+               *__get_cpu_var(tasklet_vec).tail = t;
+               __get_cpu_var(tasklet_vec).tail = &(t->next);
                __raise_softirq_irqoff(TASKLET_SOFTIRQ);
                local_irq_enable();
        }
@@ -428,8 +433,9 @@ static void tasklet_hi_action(struct softirq_action *a)
        struct tasklet_struct *list;
 
        local_irq_disable();
-       list = __get_cpu_var(tasklet_hi_vec).list;
-       __get_cpu_var(tasklet_hi_vec).list = NULL;
+       list = __get_cpu_var(tasklet_hi_vec).head;
+       __get_cpu_var(tasklet_hi_vec).head = NULL;
+       __get_cpu_var(tasklet_hi_vec).tail = &__get_cpu_var(tasklet_hi_vec).head;
        local_irq_enable();
 
        while (list) {
@@ -449,8 +455,9 @@ static void tasklet_hi_action(struct softirq_action *a)
                }
 
                local_irq_disable();
-               t->next = __get_cpu_var(tasklet_hi_vec).list;
-               __get_cpu_var(tasklet_hi_vec).list = t;
+               t->next = NULL;
+               *__get_cpu_var(tasklet_hi_vec).tail = t;
+               __get_cpu_var(tasklet_hi_vec).tail = &(t->next);
                __raise_softirq_irqoff(HI_SOFTIRQ);
                local_irq_enable();
        }
@@ -487,6 +494,15 @@ EXPORT_SYMBOL(tasklet_kill);
 
 void __init softirq_init(void)
 {
+       int cpu;
+
+       for_each_possible_cpu(cpu) {
+               per_cpu(tasklet_vec, cpu).tail =
+                       &per_cpu(tasklet_vec, cpu).head;
+               per_cpu(tasklet_hi_vec, cpu).tail =
+                       &per_cpu(tasklet_hi_vec, cpu).head;
+       }
+
        open_softirq(TASKLET_SOFTIRQ, tasklet_action, NULL);
        open_softirq(HI_SOFTIRQ, tasklet_hi_action, NULL);
 }
@@ -555,9 +571,12 @@ void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu)
                return;
 
        /* CPU is dead, so no lock needed. */
-       for (i = &per_cpu(tasklet_vec, cpu).list; *i; i = &(*i)->next) {
+       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;
                }
        }
@@ -566,20 +585,20 @@ void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu)
 
 static void takeover_tasklets(unsigned int cpu)
 {
-       struct tasklet_struct **i;
-
        /* CPU is dead, so no lock needed. */
        local_irq_disable();
 
        /* Find end, append list for that CPU. */
-       for (i = &__get_cpu_var(tasklet_vec).list; *i; i = &(*i)->next);
-       *i = per_cpu(tasklet_vec, cpu).list;
-       per_cpu(tasklet_vec, cpu).list = NULL;
+       *__get_cpu_var(tasklet_vec).tail = per_cpu(tasklet_vec, cpu).head;
+       __get_cpu_var(tasklet_vec).tail = per_cpu(tasklet_vec, cpu).tail;
+       per_cpu(tasklet_vec, cpu).head = NULL;
+       per_cpu(tasklet_vec, cpu).tail = &per_cpu(tasklet_vec, cpu).head;
        raise_softirq_irqoff(TASKLET_SOFTIRQ);
 
-       for (i = &__get_cpu_var(tasklet_hi_vec).list; *i; i = &(*i)->next);
-       *i = per_cpu(tasklet_hi_vec, cpu).list;
-       per_cpu(tasklet_hi_vec, cpu).list = NULL;
+       *__get_cpu_var(tasklet_hi_vec).tail = per_cpu(tasklet_hi_vec, cpu).head;
+       __get_cpu_var(tasklet_hi_vec).tail = per_cpu(tasklet_hi_vec, cpu).tail;
+       per_cpu(tasklet_hi_vec, cpu).head = NULL;
+       per_cpu(tasklet_hi_vec, cpu).tail = &per_cpu(tasklet_hi_vec, cpu).head;
        raise_softirq_irqoff(HI_SOFTIRQ);
 
        local_irq_enable();