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Subject[PATCH 2/8] cpumask: convert kernel/workqueue.c
Impact: Reduce memory usage, use new cpumask API.

In this case, we replace cpu_populated_map with a cpumask_var_t rather
than a bitmap because there's an obvious init function for workqueues
which happens after kmalloc is available.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
---
kernel/workqueue.c | 39 +++++++++++++++++++++------------------
1 file changed, 21 insertions(+), 18 deletions(-)
--- linux-2.6-for-ingo.orig/kernel/workqueue.c
+++ linux-2.6-for-ingo/kernel/workqueue.c
@@ -73,15 +73,15 @@ static DEFINE_SPINLOCK(workqueue_lock);
static LIST_HEAD(workqueues);

static int singlethread_cpu __read_mostly;
-static cpumask_t cpu_singlethread_map __read_mostly;
+static const struct cpumask *cpu_singlethread_map __read_mostly;
/*
- * _cpu_down() first removes CPU from cpu_online_map, then CPU_DEAD
+ * _cpu_down() first removes CPU from cpu_online_mask, then CPU_DEAD
* flushes cwq->worklist. This means that flush_workqueue/wait_on_work
* which comes in between can't use for_each_online_cpu(). We could
- * use cpu_possible_map, the cpumask below is more a documentation
+ * use cpu_possible_mask, the cpumask below is more a documentation
* than optimization.
*/
-static cpumask_t cpu_populated_map __read_mostly;
+static cpumask_var_t cpu_populated_map __read_mostly;

/* If it's single threaded, it isn't in the list of workqueues. */
static inline int is_single_threaded(struct workqueue_struct *wq)
@@ -89,10 +89,10 @@ static inline int is_single_threaded(str
return wq->singlethread;
}

-static const cpumask_t *wq_cpu_map(struct workqueue_struct *wq)
+static const struct cpumask *wq_cpu_map(struct workqueue_struct *wq)
{
return is_single_threaded(wq)
- ? &cpu_singlethread_map : &cpu_populated_map;
+ ? cpu_singlethread_map : cpu_populated_map;
}

static
@@ -410,13 +410,13 @@ static int flush_cpu_workqueue(struct cp
*/
void flush_workqueue(struct workqueue_struct *wq)
{
- const cpumask_t *cpu_map = wq_cpu_map(wq);
+ const struct cpumask *cpu_map = wq_cpu_map(wq);
int cpu;

might_sleep();
lock_map_acquire(&wq->lockdep_map);
lock_map_release(&wq->lockdep_map);
- for_each_cpu_mask_nr(cpu, *cpu_map)
+ for_each_cpu(cpu, cpu_map)
flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, cpu));
}
EXPORT_SYMBOL_GPL(flush_workqueue);
@@ -532,7 +532,7 @@ static void wait_on_work(struct work_str
{
struct cpu_workqueue_struct *cwq;
struct workqueue_struct *wq;
- const cpumask_t *cpu_map;
+ const struct cpumask *cpu_map;
int cpu;

might_sleep();
@@ -547,7 +547,7 @@ static void wait_on_work(struct work_str
wq = cwq->wq;
cpu_map = wq_cpu_map(wq);

- for_each_cpu_mask_nr(cpu, *cpu_map)
+ for_each_cpu(cpu, cpu_map)
wait_on_cpu_work(per_cpu_ptr(wq->cpu_wq, cpu), work);
}

@@ -778,7 +778,7 @@ static int create_workqueue_thread(struc
* if (caller is __create_workqueue)
* nobody should see this wq
* else // caller is CPU_UP_PREPARE
- * cpu is not on cpu_online_map
+ * cpu is not on cpu_online_mask
* so we can abort safely.
*/
if (IS_ERR(p))
@@ -903,7 +903,7 @@ static void cleanup_workqueue_thread(str
*/
void destroy_workqueue(struct workqueue_struct *wq)
{
- const cpumask_t *cpu_map = wq_cpu_map(wq);
+ const struct cpumask *cpu_map = wq_cpu_map(wq);
int cpu;

cpu_maps_update_begin();
@@ -911,7 +911,7 @@ void destroy_workqueue(struct workqueue_
list_del(&wq->list);
spin_unlock(&workqueue_lock);

- for_each_cpu_mask_nr(cpu, *cpu_map)
+ for_each_cpu(cpu, cpu_map)
cleanup_workqueue_thread(per_cpu_ptr(wq->cpu_wq, cpu));
cpu_maps_update_done();

@@ -933,7 +933,7 @@ static int __devinit workqueue_cpu_callb

switch (action) {
case CPU_UP_PREPARE:
- cpu_set(cpu, cpu_populated_map);
+ cpumask_set_cpu(cpu, cpu_populated_map);
}
undo:
list_for_each_entry(wq, &workqueues, list) {
@@ -964,7 +964,7 @@ undo:
switch (action) {
case CPU_UP_CANCELED:
case CPU_POST_DEAD:
- cpu_clear(cpu, cpu_populated_map);
+ cpumask_clear_cpu(cpu, cpu_populated_map);
}

return ret;
@@ -1017,9 +1017,12 @@ EXPORT_SYMBOL_GPL(work_on_cpu);

void __init init_workqueues(void)
{
- cpu_populated_map = cpu_online_map;
- singlethread_cpu = first_cpu(cpu_possible_map);
- cpu_singlethread_map = cpumask_of_cpu(singlethread_cpu);
+ alloc_cpumask_var(&cpu_populated_map, GFP_KERNEL);
+ cpumask_copy(cpu_populated_map, cpu_online_mask);
+
+ singlethread_cpu = cpumask_first(cpu_possible_mask);
+ cpu_singlethread_map = cpumask_of(singlethread_cpu);
+
hotcpu_notifier(workqueue_cpu_callback, 0);
keventd_wq = create_workqueue("events");
BUG_ON(!keventd_wq);
--


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