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Subject[PATCH 04/17] elevator: make elevator_init_fn() return 0/-errno
Date
elevator_ops->elevator_init_fn() has a weird return value.  It returns
a void * which the caller should assign to q->elevator->elevator_data
and %NULL return denotes init failure.

Update such that it returns integer 0/-errno and sets elevator_data
directly as necessary.

This makes the interface more conventional and eases further cleanup.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
---
block/cfq-iosched.c | 9 +++++----
block/deadline-iosched.c | 8 +++++---
block/elevator.c | 12 ++----------
block/noop-iosched.c | 8 +++++---
include/linux/elevator.h | 2 +-
5 files changed, 18 insertions(+), 21 deletions(-)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 529dfba..f3d6b04 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -3662,7 +3662,7 @@ static void cfq_exit_queue(struct elevator_queue *e)
kfree(cfqd);
}

-static void *cfq_init_queue(struct request_queue *q)
+static int cfq_init_queue(struct request_queue *q)
{
struct cfq_data *cfqd;
int i, j;
@@ -3671,7 +3671,7 @@ static void *cfq_init_queue(struct request_queue *q)

cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
if (!cfqd)
- return NULL;
+ return -ENOMEM;

/* Init root service tree */
cfqd->grp_service_tree = CFQ_RB_ROOT;
@@ -3698,7 +3698,7 @@ static void *cfq_init_queue(struct request_queue *q)
if (blkio_alloc_blkg_stats(&cfqg->blkg)) {
kfree(cfqg);
kfree(cfqd);
- return NULL;
+ return -ENOMEM;
}

rcu_read_lock();
@@ -3729,6 +3729,7 @@ static void *cfq_init_queue(struct request_queue *q)
cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group);

cfqd->queue = q;
+ q->elevator->elevator_data = cfqd;

init_timer(&cfqd->idle_slice_timer);
cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
@@ -3753,7 +3754,7 @@ static void *cfq_init_queue(struct request_queue *q)
* second, in order to have larger depth for async operations.
*/
cfqd->last_delayed_sync = jiffies - HZ;
- return cfqd;
+ return 0;
}

/*
diff --git a/block/deadline-iosched.c b/block/deadline-iosched.c
index 7bf12d7..599b12e 100644
--- a/block/deadline-iosched.c
+++ b/block/deadline-iosched.c
@@ -337,13 +337,13 @@ static void deadline_exit_queue(struct elevator_queue *e)
/*
* initialize elevator private data (deadline_data).
*/
-static void *deadline_init_queue(struct request_queue *q)
+static int deadline_init_queue(struct request_queue *q)
{
struct deadline_data *dd;

dd = kmalloc_node(sizeof(*dd), GFP_KERNEL | __GFP_ZERO, q->node);
if (!dd)
- return NULL;
+ return -ENOMEM;

INIT_LIST_HEAD(&dd->fifo_list[READ]);
INIT_LIST_HEAD(&dd->fifo_list[WRITE]);
@@ -354,7 +354,9 @@ static void *deadline_init_queue(struct request_queue *q)
dd->writes_starved = writes_starved;
dd->front_merges = 1;
dd->fifo_batch = fifo_batch;
- return dd;
+
+ q->elevator->elevator_data = dd;
+ return 0;
}

/*
diff --git a/block/elevator.c b/block/elevator.c
index 42543e3..8dc65b1 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -168,14 +168,6 @@ static struct elevator_type *elevator_get(const char *name)
return e;
}

-static int elevator_init_queue(struct request_queue *q)
-{
- q->elevator->elevator_data = q->elevator->type->ops.elevator_init_fn(q);
- if (q->elevator->elevator_data)
- return 0;
- return -ENOMEM;
-}
-
static char chosen_elevator[ELV_NAME_MAX];

static int __init elevator_setup(char *str)
@@ -271,7 +263,7 @@ int elevator_init(struct request_queue *q, char *name)
if (!q->elevator)
return -ENOMEM;

- err = elevator_init_queue(q);
+ err = e->ops.elevator_init_fn(q);
if (err) {
kobject_put(&q->elevator->kobj);
return err;
@@ -974,7 +966,7 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
if (!q->elevator)
goto fail_init;

- err = elevator_init_queue(q);
+ err = new_e->ops.elevator_init_fn(q);
if (err) {
kobject_put(&q->elevator->kobj);
goto fail_init;
diff --git a/block/noop-iosched.c b/block/noop-iosched.c
index 413a0b1..5d1bf70 100644
--- a/block/noop-iosched.c
+++ b/block/noop-iosched.c
@@ -59,15 +59,17 @@ noop_latter_request(struct request_queue *q, struct request *rq)
return list_entry(rq->queuelist.next, struct request, queuelist);
}

-static void *noop_init_queue(struct request_queue *q)
+static int noop_init_queue(struct request_queue *q)
{
struct noop_data *nd;

nd = kmalloc_node(sizeof(*nd), GFP_KERNEL, q->node);
if (!nd)
- return NULL;
+ return -ENOMEM;
+
INIT_LIST_HEAD(&nd->queue);
- return nd;
+ q->elevator->elevator_data = nd;
+ return 0;
}

static void noop_exit_queue(struct elevator_queue *e)
diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index c24f3d7..d7726c9 100644
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -33,7 +33,7 @@ typedef void (elevator_put_req_fn) (struct request *);
typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);

-typedef void *(elevator_init_fn) (struct request_queue *);
+typedef int (elevator_init_fn) (struct request_queue *);
typedef void (elevator_exit_fn) (struct elevator_queue *);

struct elevator_ops
--
1.7.7.3


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