On Tue, Feb 27, 2024 at 12:00:17PM -0800, Manjunath Patil wrote:
> Add timeout to cm_destroy_id, so that userspace can trigger any data
> collection that would help in analyzing the cause of delay in destroying
> the cm_id.
Why doesn't rdmatool resource cm_id dump help to see stalled cm_ids?
Thanks
>
> New noinline function helps dtrace/ebpf programs to hook on to it.
> Existing functionality isn't changed except triggering a probe-able new
> function at every timeout interval.
>
> We have seen cases where CM messages stuck with MAD layer (either due to
> software bug or faulty HCA), leading to cm_id getting stuck in the
> following call stack. This patch helps in resolving such issues faster.
>
> kernel: ... INFO: task XXXX:56778 blocked for more than 120 seconds.
> ...
> Call Trace:
> __schedule+0x2bc/0x895
> schedule+0x36/0x7c
> schedule_timeout+0x1f6/0x31f
> ? __slab_free+0x19c/0x2ba
> wait_for_completion+0x12b/0x18a
> ? wake_up_q+0x80/0x73
> cm_destroy_id+0x345/0x610 [ib_cm]
> ib_destroy_cm_id+0x10/0x20 [ib_cm]
> rdma_destroy_id+0xa8/0x300 [rdma_cm]
> ucma_destroy_id+0x13e/0x190 [rdma_ucm]
> ucma_write+0xe0/0x160 [rdma_ucm]
> __vfs_write+0x3a/0x16d
> vfs_write+0xb2/0x1a1
> ? syscall_trace_enter+0x1ce/0x2b8
> SyS_write+0x5c/0xd3
> do_syscall_64+0x79/0x1b9
> entry_SYSCALL_64_after_hwframe+0x16d/0x0
>
> Signed-off-by: Manjunath Patil <manjunath.b.patil@xxxxxxxxxx>
> ---
> drivers/infiniband/core/cm.c | 38 +++++++++++++++++++++++++++++++++++-
> 1 file changed, 37 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c
> index ff58058aeadc..03f7b80efa77 100644
> --- a/drivers/infiniband/core/cm.c
> +++ b/drivers/infiniband/core/cm.c
> @@ -34,6 +34,20 @@ MODULE_AUTHOR("Sean Hefty");
> MODULE_DESCRIPTION("InfiniBand CM");
> MODULE_LICENSE("Dual BSD/GPL");
>
> +static unsigned long cm_destroy_id_wait_timeout_sec = 10;
> +
> +static struct ctl_table_header *cm_ctl_table_header;
> +static struct ctl_table cm_ctl_table[] = {
> + {
> + .procname = "destroy_id_wait_timeout_sec",
> + .data = &cm_destroy_id_wait_timeout_sec,
> + .maxlen = sizeof(cm_destroy_id_wait_timeout_sec),
> + .mode = 0644,
> + .proc_handler = proc_doulongvec_minmax,
> + },
> + { }
> +};
> +
> static const char * const ibcm_rej_reason_strs[] = {
> [IB_CM_REJ_NO_QP] = "no QP",
> [IB_CM_REJ_NO_EEC] = "no EEC",
> @@ -1025,10 +1039,20 @@ static void cm_reset_to_idle(struct cm_id_private *cm_id_priv)
> }
> }
>
> +static noinline void cm_destroy_id_wait_timeout(struct ib_cm_id *cm_id)
> +{
> + struct cm_id_private *cm_id_priv;
> +
> + cm_id_priv = container_of(cm_id, struct cm_id_private, id);
> + pr_err("%s: cm_id=%p timed out. state=%d refcnt=%d\n", __func__,
> + cm_id, cm_id->state, refcount_read(&cm_id_priv->refcount));
> +}
> +
> static void cm_destroy_id(struct ib_cm_id *cm_id, int err)
> {
> struct cm_id_private *cm_id_priv;
> struct cm_work *work;
> + int ret;
>
> cm_id_priv = container_of(cm_id, struct cm_id_private, id);
> spin_lock_irq(&cm_id_priv->lock);
> @@ -1135,7 +1159,14 @@ static void cm_destroy_id(struct ib_cm_id *cm_id, int err)
>
> xa_erase(&cm.local_id_table, cm_local_id(cm_id->local_id));
> cm_deref_id(cm_id_priv);
> - wait_for_completion(&cm_id_priv->comp);
> + do {
> + ret = wait_for_completion_timeout(&cm_id_priv->comp,
> + msecs_to_jiffies(
> + cm_destroy_id_wait_timeout_sec * 1000));
> + if (!ret) /* timeout happened */
> + cm_destroy_id_wait_timeout(cm_id);
> + } while (!ret);
> +
> while ((work = cm_dequeue_work(cm_id_priv)) != NULL)
> cm_free_work(work);
>
> @@ -4505,6 +4536,10 @@ static int __init ib_cm_init(void)
> ret = ib_register_client(&cm_client);
> if (ret)
> goto error3;
> + cm_ctl_table_header = register_net_sysctl(&init_net,
> + "net/ib_cm", cm_ctl_table);
> + if (!cm_ctl_table_header)
> + pr_warn("ib_cm: couldn't register sysctl path, using default values\n");
>
> return 0;
> error3:
> @@ -4522,6 +4557,7 @@ static void __exit ib_cm_cleanup(void)
> cancel_delayed_work(&timewait_info->work.work);
> spin_unlock_irq(&cm.lock);
>
> + unregister_net_sysctl_table(cm_ctl_table_header);
> ib_unregister_client(&cm_client);
> destroy_workqueue(cm.wq);
>
> --
> 2.31.1
>
>
