See below.
On Fri, 2019-06-14 at 15:10 -0700, Himanshu Madhani wrote:
> From: Arun Easi <aeasi@xxxxxxxxxxx>
>
> BUG: unable to handle kernel NULL pointer dereference at (null)
> IP: [<ffffffffc050d10c>] qla_nvme_unregister_remote_port+0x6c/0xf0 [qla2xxx]
> PGD 800000084cf41067 PUD 84d288067 PMD 0
> Oops: 0000 [#1] SMP
> Call Trace:
> [<ffffffff98abcfdf>] process_one_work+0x17f/0x440
> [<ffffffff98abdca6>] worker_thread+0x126/0x3c0
> [<ffffffff98abdb80>] ? manage_workers.isra.26+0x2a0/0x2a0
> [<ffffffff98ac4f81>] kthread+0xd1/0xe0
> [<ffffffff98ac4eb0>] ? insert_kthread_work+0x40/0x40
> [<ffffffff9918ad37>] ret_from_fork_nospec_begin+0x21/0x21
> [<ffffffff98ac4eb0>] ? insert_kthread_work+0x40/0x40
> RIP [<ffffffffc050d10c>] qla_nvme_unregister_remote_port+0x6c/0xf0 [qla2xxx]
>
> The crash is due to a bad entry in the nvme_rport_list. This list is not
> protected, and when a remoteport_delete callback is called, driver
> traverses the list and crashes.
>
> Actually, the list could be removed and driver could traverse the main
> fcport list instead. Fix does exactly that.
>
> Signed-off-by: Arun Easi <aeasi@xxxxxxxxxxx>
> Signed-off-by: Himanshu Madhani <hmadhani@xxxxxxxxxxx>
> ---
> drivers/scsi/qla2xxx/qla_def.h | 1 -
> drivers/scsi/qla2xxx/qla_nvme.c | 52 ++++++++++++++++++++---------------------
> drivers/scsi/qla2xxx/qla_nvme.h | 1 -
> drivers/scsi/qla2xxx/qla_os.c | 1 -
> 4 files changed, 25 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/scsi/qla2xxx/qla_def.h b/drivers/scsi/qla2xxx/qla_def.h
> index 1a4095c56eee..602ed24bb806 100644
> --- a/drivers/scsi/qla2xxx/qla_def.h
> +++ b/drivers/scsi/qla2xxx/qla_def.h
> @@ -4376,7 +4376,6 @@ typedef struct scsi_qla_host {
>
> struct nvme_fc_local_port *nvme_local_port;
> struct completion nvme_del_done;
> - struct list_head nvme_rport_list;
>
> uint16_t fcoe_vlan_id;
> uint16_t fcoe_fcf_idx;
> diff --git a/drivers/scsi/qla2xxx/qla_nvme.c b/drivers/scsi/qla2xxx/qla_nvme.c
> index 22e3fba28e51..99220a3cf734 100644
> --- a/drivers/scsi/qla2xxx/qla_nvme.c
> +++ b/drivers/scsi/qla2xxx/qla_nvme.c
> @@ -14,6 +14,18 @@ static struct nvme_fc_port_template qla_nvme_fc_transport;
>
> static void qla_nvme_unregister_remote_port(struct work_struct *);
>
> +static inline
> +int qla_is_active_nvme_fcport(struct fc_port *fcport)
> +{
> + return fcport->nvme_flag & NVME_FLAG_REGISTERED;
> +}
> +
Nitpick: "qla_is_active_nvme_fcport", the qualifier "active"
does not match any of the flag definitions and this is only
checking the REGISTERED flag. Maybe "qla_is_registered_nvme_fcport"
instead? Would help to understand vs. DELETING and RESETTING case.
> +#define qla_list_for_each_nvme_fcport(_fcport, _vha) \
> +{ \
> + list_for_each_entry(_fcport, &_vha->vp_fcports, list) \
> + if (qla_is_active_nvme_fcport(_fcport)) \
> +}
> +
Like here, "if (qla_is_registered_nvme_fcport(" would be clearer.
> int qla_nvme_register_remote(struct scsi_qla_host *vha, struct fc_port *fcport)
> {
> struct qla_nvme_rport *rport;
> @@ -74,7 +86,6 @@ int qla_nvme_register_remote(struct scsi_qla_host *vha, struct fc_port *fcport)
>
> rport = fcport->nvme_remote_port->private;
> rport->fcport = fcport;
> - list_add_tail(&rport->list, &vha->nvme_rport_list);
>
> fcport->nvme_flag |= NVME_FLAG_REGISTERED;
> return 0;
> @@ -542,19 +553,12 @@ static void qla_nvme_localport_delete(struct nvme_fc_local_port *lport)
> static void qla_nvme_remoteport_delete(struct nvme_fc_remote_port *rport)
> {
> fc_port_t *fcport;
> - struct qla_nvme_rport *qla_rport = rport->private, *trport;
> + struct qla_nvme_rport *qla_rport = rport->private;
>
> fcport = qla_rport->fcport;
> fcport->nvme_remote_port = NULL;
> fcport->nvme_flag &= ~NVME_FLAG_REGISTERED;
>
> - list_for_each_entry_safe(qla_rport, trport,
> - &fcport->vha->nvme_rport_list, list) {
> - if (qla_rport->fcport == fcport) {
> - list_del(&qla_rport->list);
> - break;
> - }
> - }
> complete(&fcport->nvme_del_done);
>
> if (!test_bit(UNLOADING, &fcport->vha->dpc_flags)) {
> @@ -590,31 +594,25 @@ static void qla_nvme_unregister_remote_port(struct work_struct *work)
> {
> struct fc_port *fcport = container_of(work, struct fc_port,
> nvme_del_work);
> - struct qla_nvme_rport *qla_rport, *trport;
> + int ret;
>
> if (!IS_ENABLED(CONFIG_NVME_FC))
> return;
>
> + if (!qla_is_active_nvme_fcport(fcport))
> + return;
> +
This looks like it is prone to a race because the REGISTERED flag
is cleared in the callback from the NVMe transport? The flag was
already checked in qlt_unreg_sess(), then the work item runs here,
then later qla_nvme_remoteport_delete() runs. What is happening
here that the check is preventing?
-Ewan
> ql_log(ql_log_warn, NULL, 0x2112,
> "%s: unregister remoteport on %p\n",__func__, fcport);
>
> - list_for_each_entry_safe(qla_rport, trport,
> - &fcport->vha->nvme_rport_list, list) {
> - if (qla_rport->fcport == fcport) {
> - ql_log(ql_log_info, fcport->vha, 0x2113,
> - "%s: fcport=%p\n", __func__, fcport);
> - nvme_fc_set_remoteport_devloss
> - (fcport->nvme_remote_port, 0);
> - init_completion(&fcport->nvme_del_done);
> - if (nvme_fc_unregister_remoteport
> - (fcport->nvme_remote_port))
> - ql_log(ql_log_info, fcport->vha, 0x2114,
> - "%s: Failed to unregister nvme_remote_port\n",
> - __func__);
> - wait_for_completion(&fcport->nvme_del_done);
> - break;
> - }
> - }
> + nvme_fc_set_remoteport_devloss(fcport->nvme_remote_port, 0);
> + init_completion(&fcport->nvme_del_done);
> + ret = nvme_fc_unregister_remoteport(fcport->nvme_remote_port);
> + if (ret)
> + ql_log(ql_log_info, fcport->vha, 0x2114,
> + "%s: Failed to unregister nvme_remote_port (%d)\n",
> + __func__, ret);
> + wait_for_completion(&fcport->nvme_del_done);
> }
>
> void qla_nvme_delete(struct scsi_qla_host *vha)
> diff --git a/drivers/scsi/qla2xxx/qla_nvme.h b/drivers/scsi/qla2xxx/qla_nvme.h
> index d3b8a6440113..2d088add7011 100644
> --- a/drivers/scsi/qla2xxx/qla_nvme.h
> +++ b/drivers/scsi/qla2xxx/qla_nvme.h
> @@ -37,7 +37,6 @@ struct nvme_private {
> };
>
> struct qla_nvme_rport {
> - struct list_head list;
> struct fc_port *fcport;
> };
>
> diff --git a/drivers/scsi/qla2xxx/qla_os.c b/drivers/scsi/qla2xxx/qla_os.c
> index 00fee5bf4de1..ae93ae2b6090 100644
> --- a/drivers/scsi/qla2xxx/qla_os.c
> +++ b/drivers/scsi/qla2xxx/qla_os.c
> @@ -4789,7 +4789,6 @@ struct scsi_qla_host *qla2x00_create_host(struct scsi_host_template *sht,
> INIT_LIST_HEAD(&vha->plogi_ack_list);
> INIT_LIST_HEAD(&vha->qp_list);
> INIT_LIST_HEAD(&vha->gnl.fcports);
> - INIT_LIST_HEAD(&vha->nvme_rport_list);
> INIT_LIST_HEAD(&vha->gpnid_list);
> INIT_WORK(&vha->iocb_work, qla2x00_iocb_work_fn);
>
