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Subject[PATCH v2 8/8] blk-mq: Cleanup (de-)allocation of blk_mq_hw_ctx::ctxs
Date
Handling of blk_mq_hw_ctx::ctxs field (de-)allocation is
confusing due to special treatment of the field introduced
in commit c3b4afca7023 ("blk-mq: free hctx->ctxs in queue's
release handler")'. Make it bit more readable by binding
hctx and hctx->ctxs (de-)allocation.

CC: linux-block@vger.kernel.org
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
---
block/blk-mq.c | 51 ++++++++++++++++++++++++++++++++-------------------
1 file changed, 32 insertions(+), 19 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 78ee5af..03654af 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1641,18 +1641,9 @@ static int blk_mq_init_hctx(struct request_queue *q,

hctx->tags = set->tags[hctx_idx];

- /*
- * Allocate space for all possible cpus to avoid allocation at
- * runtime
- */
- hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
- GFP_KERNEL, node);
- if (!hctx->ctxs)
- goto unregister_cpu_notifier;
-
if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8), GFP_KERNEL,
node))
- goto free_ctxs;
+ goto unregister_cpu_notifier;

hctx->nr_ctx = 0;

@@ -1679,8 +1670,6 @@ static int blk_mq_init_hctx(struct request_queue *q,
set->ops->exit_hctx(hctx, hctx_idx);
free_bitmap:
sbitmap_free(&hctx->ctx_map);
- free_ctxs:
- kfree(hctx->ctxs);
unregister_cpu_notifier:
blk_mq_remove_cpuhp(hctx);
free_cpumask_var(hctx->cpumask);
@@ -1848,6 +1837,33 @@ static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
mutex_unlock(&set->tag_list_lock);
}

+static struct blk_mq_hw_ctx *alloc_hctx(int node)
+{
+ struct blk_mq_hw_ctx *hctx = kzalloc_node(sizeof(*hctx),
+ GFP_KERNEL, node);
+ if (!hctx)
+ return NULL;
+
+ /*
+ * Allocate space for all possible cpus to avoid allocation at
+ * runtime
+ */
+ hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
+ GFP_KERNEL, node);
+ if (!hctx->ctxs) {
+ kfree(hctx);
+ return NULL;
+ }
+
+ return hctx;
+}
+
+static void free_hctx(struct blk_mq_hw_ctx *hctx)
+{
+ kfree(hctx->ctxs);
+ kfree(hctx);
+}
+
/*
* It is the actual release handler for mq, but we do it from
* request queue's release handler for avoiding use-after-free
@@ -1863,8 +1879,7 @@ void blk_mq_release(struct request_queue *q)
queue_for_each_hw_ctx(q, hctx, i) {
if (!hctx)
continue;
- kfree(hctx->ctxs);
- kfree(hctx);
+ free_hctx(hctx);
}

q->mq_map = NULL;
@@ -1909,12 +1924,12 @@ static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
if (node == NUMA_NO_NODE)
node = set->numa_node;

- hctx = kzalloc_node(sizeof(*hctx), GFP_KERNEL, node);
+ hctx = alloc_hctx(node);
if (!hctx)
break;

if (blk_mq_init_hctx(q, set, hctx, i, node)) {
- kfree(hctx);
+ free_hctx(hctx);
break;
}

@@ -1936,9 +1951,7 @@ static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
}

blk_mq_exit_hctx(q, set, hctx, j);
-
- kfree(hctx->ctxs);
- kfree(hctx);
+ free_hctx(hctx);
}
q->nr_hw_queues = i;
blk_mq_sysfs_register(q);
--
1.8.3.1
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