selftests: ublk: kublk: lift queue initialization out of thread

Currently, each ublk server I/O handler thread initializes its own
queue. However, as we move towards decoupled ublk_queues and ublk server
threads, this model does not make sense anymore, as there will no longer
be a concept of a thread having "its own" queue. So lift queue
initialization out of the per-thread ublk_io_handler_fn and into a loop
in ublk_start_daemon (which runs once for each device).

There is a part of ublk_queue_init (ring initialization) which does
actually need to happen on the thread that will use the ring; that is
separated into a separate ublk_thread_init which is still called by each
I/O handler thread.

Signed-off-by: Uday Shankar <ushankar@purestorage.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250529-ublk_task_per_io-v8-4-e9d3b119336a@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/tools/testing/selftests/ublk/kublk.c b/tools/testing/selftests/ublk/kublk.c
index 1602cf6f07a02e5dab293b91f301218c38c8f4d9..2d6d163b74483a07066f47fd36781782ce25a16e 100644 (file)
--- a/tools/testing/selftests/ublk/kublk.c
+++ b/tools/testing/selftests/ublk/kublk.c
@@ -412,6 +412,17 @@ static void ublk_queue_deinit(struct ublk_queue *q)
        int i;
        int nr_ios = q->q_depth;
 
+       if (q->io_cmd_buf)
+               munmap(q->io_cmd_buf, ublk_queue_cmd_buf_sz(q));
+
+       for (i = 0; i < nr_ios; i++)
+               free(q->ios[i].buf_addr);
+}
+
+static void ublk_thread_deinit(struct ublk_queue *q)
+{
+       q->tid = 0;
+
        io_uring_unregister_buffers(&q->ring);
 
        io_uring_unregister_ring_fd(&q->ring);
@@ -421,28 +432,20 @@ static void ublk_queue_deinit(struct ublk_queue *q)
                close(q->ring.ring_fd);
                q->ring.ring_fd = -1;
        }
-
-       if (q->io_cmd_buf)
-               munmap(q->io_cmd_buf, ublk_queue_cmd_buf_sz(q));
-
-       for (i = 0; i < nr_ios; i++)
-               free(q->ios[i].buf_addr);
 }
 
 static int ublk_queue_init(struct ublk_queue *q, unsigned extra_flags)
 {
        struct ublk_dev *dev = q->dev;
        int depth = dev->dev_info.queue_depth;
-       int i, ret = -1;
+       int i;
        int cmd_buf_size, io_buf_size;
        unsigned long off;
-       int ring_depth = dev->tgt.sq_depth, cq_depth = dev->tgt.cq_depth;
 
        q->tgt_ops = dev->tgt.ops;
        q->state = 0;
        q->q_depth = depth;
        q->cmd_inflight = 0;
-       q->tid = gettid();
 
        if (dev->dev_info.flags & (UBLK_F_SUPPORT_ZERO_COPY | UBLK_F_AUTO_BUF_REG)) {
                q->state |= UBLKSRV_NO_BUF;
@@ -479,6 +482,22 @@ static int ublk_queue_init(struct ublk_queue *q, unsigned extra_flags)
                }
        }
 
+       return 0;
+ fail:
+       ublk_queue_deinit(q);
+       ublk_err("ublk dev %d queue %d failed\n",
+                       dev->dev_info.dev_id, q->q_id);
+       return -ENOMEM;
+}
+
+static int ublk_thread_init(struct ublk_queue *q)
+{
+       struct ublk_dev *dev = q->dev;
+       int ring_depth = dev->tgt.sq_depth, cq_depth = dev->tgt.cq_depth;
+       int ret;
+
+       q->tid = gettid();
+
        ret = ublk_setup_ring(&q->ring, ring_depth, cq_depth,
                        IORING_SETUP_COOP_TASKRUN |
                        IORING_SETUP_SINGLE_ISSUER |
@@ -508,9 +527,9 @@ static int ublk_queue_init(struct ublk_queue *q, unsigned extra_flags)
        }
 
        return 0;
- fail:
-       ublk_queue_deinit(q);
-       ublk_err("ublk dev %d queue %d failed\n",
+fail:
+       ublk_thread_deinit(q);
+       ublk_err("ublk dev %d queue %d thread init failed\n",
                        dev->dev_info.dev_id, q->q_id);
        return -ENOMEM;
 }
@@ -778,7 +797,6 @@ struct ublk_queue_info {
        struct ublk_queue       *q;
        sem_t                   *queue_sem;
        cpu_set_t               *affinity;
-       unsigned char           auto_zc_fallback;
 };
 
 static void *ublk_io_handler_fn(void *data)
@@ -786,15 +804,11 @@ static void *ublk_io_handler_fn(void *data)
        struct ublk_queue_info *info = data;
        struct ublk_queue *q = info->q;
        int dev_id = q->dev->dev_info.dev_id;
-       unsigned extra_flags = 0;
        int ret;
 
-       if (info->auto_zc_fallback)
-               extra_flags = UBLKSRV_AUTO_BUF_REG_FALLBACK;
-
-       ret = ublk_queue_init(q, extra_flags);
+       ret = ublk_thread_init(q);
        if (ret) {
-               ublk_err("ublk dev %d queue %d init queue failed\n",
+               ublk_err("ublk dev %d queue %d thread init failed\n",
                                dev_id, q->q_id);
                return NULL;
        }
@@ -813,7 +827,7 @@ static void *ublk_io_handler_fn(void *data)
        } while (1);
 
        ublk_dbg(UBLK_DBG_QUEUE, "ublk dev %d queue %d exited\n", dev_id, q->q_id);
-       ublk_queue_deinit(q);
+       ublk_thread_deinit(q);
        return NULL;
 }
 
@@ -857,6 +871,7 @@ static int ublk_start_daemon(const struct dev_ctx *ctx, struct ublk_dev *dev)
 {
        const struct ublksrv_ctrl_dev_info *dinfo = &dev->dev_info;
        struct ublk_queue_info *qinfo;
+       unsigned extra_flags = 0;
        cpu_set_t *affinity_buf;
        void *thread_ret;
        sem_t queue_sem;
@@ -878,14 +893,23 @@ static int ublk_start_daemon(const struct dev_ctx *ctx, struct ublk_dev *dev)
        if (ret)
                return ret;
 
+       if (ctx->auto_zc_fallback)
+               extra_flags = UBLKSRV_AUTO_BUF_REG_FALLBACK;
+
        for (i = 0; i < dinfo->nr_hw_queues; i++) {
                dev->q[i].dev = dev;
                dev->q[i].q_id = i;
 
+               ret = ublk_queue_init(&dev->q[i], extra_flags);
+               if (ret) {
+                       ublk_err("ublk dev %d queue %d init queue failed\n",
+                                dinfo->dev_id, i);
+                       goto fail;
+               }
+
                qinfo[i].q = &dev->q[i];
                qinfo[i].queue_sem = &queue_sem;
                qinfo[i].affinity = &affinity_buf[i];
-               qinfo[i].auto_zc_fallback = ctx->auto_zc_fallback;
                pthread_create(&dev->q[i].thread, NULL,
                                ublk_io_handler_fn,
                                &qinfo[i]);
@@ -918,6 +942,8 @@ static int ublk_start_daemon(const struct dev_ctx *ctx, struct ublk_dev *dev)
        for (i = 0; i < dinfo->nr_hw_queues; i++)
                pthread_join(dev->q[i].thread, &thread_ret);
  fail:
+       for (i = 0; i < dinfo->nr_hw_queues; i++)
+               ublk_queue_deinit(&dev->q[i]);
        ublk_dev_unprep(dev);
        ublk_dbg(UBLK_DBG_DEV, "%s exit\n", __func__);