From: Ming Lei <ming.lei@redhat.com>
Date: Tue, 8 Mar 2022 15:32:19 +0800
Subject: [PATCH] blk-mq: manage hctx map via xarray
Git-commit: 4e5cc99e1e485954a9c09872e0eeea570fb2b5a5
Patch-mainline: v5.18-rc1
References: jsc#PED-1183
First code becomes more clean by switching to xarray from plain array.
Second use-after-free on q->queue_hw_ctx can be fixed because
queue_for_each_hw_ctx() may be run when updating nr_hw_queues is
in-progress. With this patch, q->hctx_table is defined as xarray, and
this structure will share same lifetime with request queue, so
queue_for_each_hw_ctx() can use q->hctx_table to lookup hctx reliably.
Reported-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220308073219.91173-7-ming.lei@redhat.com
[axboe: fix blk_mq_hw_ctx forward declaration]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Hannes Reinecke <hare@suse.com>
---
block/blk-mq-debugfs.h | 2 ++
block/blk-mq-tag.c | 2 +-
block/blk-mq.c | 62 ++++++++++++++++--------------------------
block/blk-mq.h | 2 +-
include/linux/blk-mq.h | 3 +-
include/linux/blkdev.h | 2 +-
6 files changed, 30 insertions(+), 43 deletions(-)
diff --git a/block/blk-mq-debugfs.h b/block/blk-mq-debugfs.h
index a68aa6041a10..69918f4170d6 100644
--- a/block/blk-mq-debugfs.h
+++ b/block/blk-mq-debugfs.h
@@ -6,6 +6,8 @@
#include <linux/seq_file.h>
+struct blk_mq_hw_ctx;
+
struct blk_mq_debugfs_attr {
const char *name;
umode_t mode;
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index 1850a4225e12..68ac23d0b640 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -498,7 +498,7 @@ void blk_mq_queue_tag_busy_iter(struct request_queue *q, busy_tag_iter_fn *fn,
void *priv)
{
/*
- * __blk_mq_update_nr_hw_queues() updates nr_hw_queues and queue_hw_ctx
+ * __blk_mq_update_nr_hw_queues() updates nr_hw_queues and hctx_table
* while the queue is frozen. So we can use q_usage_counter to avoid
* racing with it.
*/
diff --git a/block/blk-mq.c b/block/blk-mq.c
index bffdd71c670d..e8d6d7a05a43 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -71,7 +71,8 @@ static int blk_mq_poll_stats_bkt(const struct request *rq)
static inline struct blk_mq_hw_ctx *blk_qc_to_hctx(struct request_queue *q,
blk_qc_t qc)
{
- return q->queue_hw_ctx[(qc & ~BLK_QC_T_INTERNAL) >> BLK_QC_T_SHIFT];
+ return xa_load(&q->hctx_table,
+ (qc & ~BLK_QC_T_INTERNAL) >> BLK_QC_T_SHIFT);
}
static inline struct request *blk_qc_to_rq(struct blk_mq_hw_ctx *hctx,
@@ -573,7 +574,7 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
* If not tell the caller that it should skip this queue.
*/
ret = -EXDEV;
- data.hctx = q->queue_hw_ctx[hctx_idx];
+ data.hctx = xa_load(&q->hctx_table, hctx_idx);
if (!blk_mq_hw_queue_mapped(data.hctx))
goto out_queue_exit;
cpu = cpumask_first_and(data.hctx->cpumask, cpu_online_mask);
@@ -3437,6 +3438,8 @@ static void blk_mq_exit_hctx(struct request_queue *q,
blk_mq_remove_cpuhp(hctx);
+ xa_erase(&q->hctx_table, hctx_idx);
+
spin_lock(&q->unused_hctx_lock);
list_add(&hctx->hctx_list, &q->unused_hctx_list);
spin_unlock(&q->unused_hctx_lock);
@@ -3476,8 +3479,15 @@ static int blk_mq_init_hctx(struct request_queue *q,
if (blk_mq_init_request(set, hctx->fq->flush_rq, hctx_idx,
hctx->numa_node))
goto exit_hctx;
+
+ if (xa_insert(&q->hctx_table, hctx_idx, hctx, GFP_KERNEL))
+ goto exit_flush_rq;
+
return 0;
+ exit_flush_rq:
+ if (set->ops->exit_request)
+ set->ops->exit_request(set, hctx->fq->flush_rq, hctx_idx);
exit_hctx:
if (set->ops->exit_hctx)
set->ops->exit_hctx(hctx, hctx_idx);
@@ -3856,7 +3866,7 @@ void blk_mq_release(struct request_queue *q)
kobject_put(&hctx->kobj);
}
- kfree(q->queue_hw_ctx);
+ xa_destroy(&q->hctx_table);
/*
* release .mq_kobj and sw queue's kobject now because
@@ -3945,46 +3955,28 @@ static struct blk_mq_hw_ctx *blk_mq_alloc_and_init_hctx(
static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
struct request_queue *q)
{
- int i, j, end;
- struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
-
- if (q->nr_hw_queues < set->nr_hw_queues) {
- struct blk_mq_hw_ctx **new_hctxs;
-
- new_hctxs = kcalloc_node(set->nr_hw_queues,
- sizeof(*new_hctxs), GFP_KERNEL,
- set->numa_node);
- if (!new_hctxs)
- return;
- if (hctxs)
- memcpy(new_hctxs, hctxs, q->nr_hw_queues *
- sizeof(*hctxs));
- q->queue_hw_ctx = new_hctxs;
- kfree(hctxs);
- hctxs = new_hctxs;
- }
+ struct blk_mq_hw_ctx *hctx;
+ unsigned long i, j;
/* protect against switching io scheduler */
mutex_lock(&q->sysfs_lock);
for (i = 0; i < set->nr_hw_queues; i++) {
int old_node;
int node = blk_mq_get_hctx_node(set, i);
- struct blk_mq_hw_ctx *old_hctx = hctxs[i];
+ struct blk_mq_hw_ctx *old_hctx = xa_load(&q->hctx_table, i);
if (old_hctx) {
old_node = old_hctx->numa_node;
blk_mq_exit_hctx(q, set, old_hctx, i);
}
- hctxs[i] = blk_mq_alloc_and_init_hctx(set, q, i, node);
- if (!hctxs[i]) {
+ if (!blk_mq_alloc_and_init_hctx(set, q, i, node)) {
if (!old_hctx)
break;
pr_warn("Allocate new hctx on node %d fails, fallback to previous one on node %d\n",
node, old_node);
- hctxs[i] = blk_mq_alloc_and_init_hctx(set, q, i,
- old_node);
- WARN_ON_ONCE(!hctxs[i]);
+ hctx = blk_mq_alloc_and_init_hctx(set, q, i, old_node);
+ WARN_ON_ONCE(!hctx);
}
}
/*
@@ -3993,21 +3985,13 @@ static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
*/
if (i != set->nr_hw_queues) {
j = q->nr_hw_queues;
- end = i;
} else {
j = i;
- end = q->nr_hw_queues;
q->nr_hw_queues = set->nr_hw_queues;
}
- for (; j < end; j++) {
- struct blk_mq_hw_ctx *hctx = hctxs[j];
-
- if (hctx) {
- blk_mq_exit_hctx(q, set, hctx, j);
- hctxs[j] = NULL;
- }
- }
+ xa_for_each_start(&q->hctx_table, j, hctx, j)
+ blk_mq_exit_hctx(q, set, hctx, j);
mutex_unlock(&q->sysfs_lock);
}
@@ -4046,6 +4030,8 @@ int blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
INIT_LIST_HEAD(&q->unused_hctx_list);
spin_lock_init(&q->unused_hctx_lock);
+ xa_init(&q->hctx_table);
+
blk_mq_realloc_hw_ctxs(set, q);
if (!q->nr_hw_queues)
goto err_hctxs;
@@ -4075,7 +4061,7 @@ int blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
return 0;
err_hctxs:
- kfree(q->queue_hw_ctx);
+ xa_destroy(&q->hctx_table);
q->nr_hw_queues = 0;
blk_mq_sysfs_deinit(q);
err_poll:
diff --git a/block/blk-mq.h b/block/blk-mq.h
index 948791ea2a3e..2615bd58bad3 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -83,7 +83,7 @@ static inline struct blk_mq_hw_ctx *blk_mq_map_queue_type(struct request_queue *
enum hctx_type type,
unsigned int cpu)
{
- return q->queue_hw_ctx[q->tag_set->map[type].mq_map[cpu]];
+ return xa_load(&q->hctx_table, q->tag_set->map[type].mq_map[cpu]);
}
static inline enum hctx_type blk_mq_get_hctx_type(unsigned int flags)
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 3a41d50b85d3..7aa5c54901a9 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -917,8 +917,7 @@ static inline void *blk_mq_rq_to_pdu(struct request *rq)
}
#define queue_for_each_hw_ctx(q, hctx, i) \
- for ((i) = 0; (i) < (q)->nr_hw_queues && \
- ({ hctx = (q)->queue_hw_ctx[i]; 1; }); (i)++)
+ xa_for_each(&(q)->hctx_table, (i), (hctx))
#define hctx_for_each_ctx(hctx, ctx, i) \
for ((i) = 0; (i) < (hctx)->nr_ctx && \
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index e19947d84f12..d982171469bc 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -355,7 +355,7 @@ struct request_queue {
unsigned int queue_depth;
/* hw dispatch queues */
- struct blk_mq_hw_ctx **queue_hw_ctx;
+ struct xarray hctx_table;
unsigned int nr_hw_queues;
/*
--
2.35.3