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-rw-r--r--block/blk-mq-cpumap.c9
-rw-r--r--block/blk-mq.c59
-rw-r--r--block/blk-mq.h3
3 files changed, 52 insertions, 19 deletions
diff --git a/block/blk-mq-cpumap.c b/block/blk-mq-cpumap.c
index 1e28ddb..8764c24 100644
--- a/block/blk-mq-cpumap.c
+++ b/block/blk-mq-cpumap.c
@@ -31,7 +31,8 @@ static int get_first_sibling(unsigned int cpu)
return cpu;
}
-int blk_mq_update_queue_map(unsigned int *map, unsigned int nr_queues)
+int blk_mq_update_queue_map(unsigned int *map, unsigned int nr_queues,
+ const struct cpumask *online_mask)
{
unsigned int i, nr_cpus, nr_uniq_cpus, queue, first_sibling;
cpumask_var_t cpus;
@@ -41,7 +42,7 @@ int blk_mq_update_queue_map(unsigned int *map, unsigned int nr_queues)
cpumask_clear(cpus);
nr_cpus = nr_uniq_cpus = 0;
- for_each_online_cpu(i) {
+ for_each_cpu(i, online_mask) {
nr_cpus++;
first_sibling = get_first_sibling(i);
if (!cpumask_test_cpu(first_sibling, cpus))
@@ -51,7 +52,7 @@ int blk_mq_update_queue_map(unsigned int *map, unsigned int nr_queues)
queue = 0;
for_each_possible_cpu(i) {
- if (!cpu_online(i)) {
+ if (!cpumask_test_cpu(i, online_mask)) {
map[i] = 0;
continue;
}
@@ -95,7 +96,7 @@ unsigned int *blk_mq_make_queue_map(struct blk_mq_tag_set *set)
if (!map)
return NULL;
- if (!blk_mq_update_queue_map(map, set->nr_hw_queues))
+ if (!blk_mq_update_queue_map(map, set->nr_hw_queues, cpu_online_mask))
return map;
kfree(map);
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 3a39184..a5dbd06 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1789,7 +1789,8 @@ static void blk_mq_init_cpu_queues(struct request_queue *q,
}
}
-static void blk_mq_map_swqueue(struct request_queue *q)
+static void blk_mq_map_swqueue(struct request_queue *q,
+ const struct cpumask *online_mask)
{
unsigned int i;
struct blk_mq_hw_ctx *hctx;
@@ -1806,7 +1807,7 @@ static void blk_mq_map_swqueue(struct request_queue *q)
*/
queue_for_each_ctx(q, ctx, i) {
/* If the cpu isn't online, the cpu is mapped to first hctx */
- if (!cpu_online(i))
+ if (!cpumask_test_cpu(i, online_mask))
continue;
hctx = q->mq_ops->map_queue(q, i);
@@ -1852,7 +1853,7 @@ static void blk_mq_map_swqueue(struct request_queue *q)
}
queue_for_each_ctx(q, ctx, i) {
- if (!cpu_online(i))
+ if (!cpumask_test_cpu(i, online_mask))
continue;
hctx = q->mq_ops->map_queue(q, i);
@@ -2037,13 +2038,15 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
if (blk_mq_init_hw_queues(q, set))
goto err_hctxs;
+ get_online_cpus();
mutex_lock(&all_q_mutex);
list_add_tail(&q->all_q_node, &all_q_list);
blk_mq_add_queue_tag_set(set, q);
- blk_mq_map_swqueue(q);
+ blk_mq_map_swqueue(q, cpu_online_mask);
mutex_unlock(&all_q_mutex);
+ put_online_cpus();
return q;
@@ -2080,13 +2083,14 @@ void blk_mq_free_queue(struct request_queue *q)
}
/* Basically redo blk_mq_init_queue with queue frozen */
-static void blk_mq_queue_reinit(struct request_queue *q)
+static void blk_mq_queue_reinit(struct request_queue *q,
+ const struct cpumask *online_mask)
{
WARN_ON_ONCE(!atomic_read(&q->mq_freeze_depth));
blk_mq_sysfs_unregister(q);
- blk_mq_update_queue_map(q->mq_map, q->nr_hw_queues);
+ blk_mq_update_queue_map(q->mq_map, q->nr_hw_queues, online_mask);
/*
* redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
@@ -2094,7 +2098,7 @@ static void blk_mq_queue_reinit(struct request_queue *q)
* involves free and re-allocate memory, worthy doing?)
*/
- blk_mq_map_swqueue(q);
+ blk_mq_map_swqueue(q, online_mask);
blk_mq_sysfs_register(q);
}
@@ -2103,16 +2107,43 @@ static int blk_mq_queue_reinit_notify(struct notifier_block *nb,
unsigned long action, void *hcpu)
{
struct request_queue *q;
+ int cpu = (unsigned long)hcpu;
+ /*
+ * New online cpumask which is going to be set in this hotplug event.
+ * Declare this cpumasks as global as cpu-hotplug operation is invoked
+ * one-by-one and dynamically allocating this could result in a failure.
+ */
+ static struct cpumask online_new;
/*
- * Before new mappings are established, hotadded cpu might already
- * start handling requests. This doesn't break anything as we map
- * offline CPUs to first hardware queue. We will re-init the queue
- * below to get optimal settings.
+ * Before hotadded cpu starts handling requests, new mappings must
+ * be established. Otherwise, these requests in hw queue might
+ * never be dispatched.
+ *
+ * For example, there is a single hw queue (hctx) and two CPU queues
+ * (ctx0 for CPU0, and ctx1 for CPU1).
+ *
+ * Now CPU1 is just onlined and a request is inserted into
+ * ctx1->rq_list and set bit0 in pending bitmap as ctx1->index_hw is
+ * still zero.
+ *
+ * And then while running hw queue, flush_busy_ctxs() finds bit0 is
+ * set in pending bitmap and tries to retrieve requests in
+ * hctx->ctxs[0]->rq_list. But htx->ctxs[0] is a pointer to ctx0,
+ * so the request in ctx1->rq_list is ignored.
*/
- if (action != CPU_DEAD && action != CPU_DEAD_FROZEN &&
- action != CPU_ONLINE && action != CPU_ONLINE_FROZEN)
+ switch (action & ~CPU_TASKS_FROZEN) {
+ case CPU_DEAD:
+ case CPU_UP_CANCELED:
+ cpumask_copy(&online_new, cpu_online_mask);
+ break;
+ case CPU_UP_PREPARE:
+ cpumask_copy(&online_new, cpu_online_mask);
+ cpumask_set_cpu(cpu, &online_new);
+ break;
+ default:
return NOTIFY_OK;
+ }
mutex_lock(&all_q_mutex);
@@ -2136,7 +2167,7 @@ static int blk_mq_queue_reinit_notify(struct notifier_block *nb,
}
list_for_each_entry(q, &all_q_list, all_q_node)
- blk_mq_queue_reinit(q);
+ blk_mq_queue_reinit(q, &online_new);
list_for_each_entry(q, &all_q_list, all_q_node)
blk_mq_unfreeze_queue(q);
diff --git a/block/blk-mq.h b/block/blk-mq.h
index 6a48c4c..f4fea79 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -51,7 +51,8 @@ void blk_mq_disable_hotplug(void);
* CPU -> queue mappings
*/
extern unsigned int *blk_mq_make_queue_map(struct blk_mq_tag_set *set);
-extern int blk_mq_update_queue_map(unsigned int *map, unsigned int nr_queues);
+extern int blk_mq_update_queue_map(unsigned int *map, unsigned int nr_queues,
+ const struct cpumask *online_mask);
extern int blk_mq_hw_queue_to_node(unsigned int *map, unsigned int);
/*
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