Re: [smartpqi updates PATCH V2 04/11] smartpqi: update LUN reset handler

john.p.donnelly
2021-09-30T18:23:16Z

On 9/28/21 6:54 PM, Don Brace wrote:
> From: Kevin Barnett <kevin.barnett@microchip.com>
>
> Enhance check for commands queued to the controller.
> - Add new function pqi_nonempty_inbound_queue_count that
> will wait for all I/O queued for submission to controller
> across all queue groups to drain. Add helper functions
> to obtain queue command counts for each queue group.
> These queues should drain quickly as they are already staged
> to be submitted down to the controller's IB queue.
> Enhance check for outstanding command completion.
> - Update the count of outstanding commands while waiting.
> This value was not re-obtained and was potentially causing
> infinite wait for all completions.
>
> Reviewed-by: Scott Benesh <scott.benesh@microchip.com>
> Reviewed-by: Scott Teel <scott.teel@microchip.com>
> Reviewed-by: Mike McGowen <mike.mcgowen@microchip.com>
> Signed-off-by: Kevin Barnett <kevin.barnett@microchip.com>
> Signed-off-by: Don Brace <don.brace@microchip.com>

Acked-by: John Donnelly <john.p.donnelly@oracle.com>

> ---
> drivers/scsi/smartpqi/smartpqi_init.c | 105 ++++++++++++++++----------
> 1 file changed, 66 insertions(+), 39 deletions(-)
>
> diff --git a/drivers/scsi/smartpqi/smartpqi_init.c b/drivers/scsi/smartpqi/smartpqi_init.c
> index b6ac4d607664..01330fd67500 100644
> --- a/drivers/scsi/smartpqi/smartpqi_init.c
> +++ b/drivers/scsi/smartpqi/smartpqi_init.c
> @@ -5799,64 +5799,91 @@ static int pqi_scsi_queue_command(struct Scsi_Host *shost, struct scsi_cmnd *scm
> return rc;
> }
>
> -static int pqi_wait_until_queued_io_drained(struct pqi_ctrl_info *ctrl_info,
> - struct pqi_queue_group *queue_group)
> +static unsigned int pqi_queued_io_count(struct pqi_ctrl_info *ctrl_info)
> {
> + unsigned int i;
> unsigned int path;
> unsigned long flags;
> - bool list_is_empty;
> + unsigned int queued_io_count;
> + struct pqi_queue_group *queue_group;
> + struct pqi_io_request *io_request;
>
> - for (path = 0; path < 2; path++) {
> - while (1) {
> - spin_lock_irqsave(
> - &queue_group->submit_lock[path], flags);
> - list_is_empty =
> - list_empty(&queue_group->request_list[path]);
> - spin_unlock_irqrestore(
> - &queue_group->submit_lock[path], flags);
> - if (list_is_empty)
> - break;
> - pqi_check_ctrl_health(ctrl_info);
> - if (pqi_ctrl_offline(ctrl_info))
> - return -ENXIO;
> - usleep_range(1000, 2000);
> + queued_io_count = 0;
> +
> + for (i = 0; i < ctrl_info->num_queue_groups; i++) {
> + queue_group = &ctrl_info->queue_groups[i];
> + for (path = 0; path < 2; path++) {
> + spin_lock_irqsave(&queue_group->submit_lock[path], flags);
> + list_for_each_entry(io_request, &queue_group->request_list[path], request_list_entry)
> + queued_io_count++;
> + spin_unlock_irqrestore(&queue_group->submit_lock[path], flags);
> }
> }
>
> - return 0;
> + return queued_io_count;
> }
>
> -static int pqi_wait_until_inbound_queues_empty(struct pqi_ctrl_info *ctrl_info)
> +static unsigned int pqi_nonempty_inbound_queue_count(struct pqi_ctrl_info *ctrl_info)
> {
> - int rc;
> unsigned int i;
> unsigned int path;
> + unsigned int nonempty_inbound_queue_count;
> struct pqi_queue_group *queue_group;
> pqi_index_t iq_pi;
> pqi_index_t iq_ci;
>
> + nonempty_inbound_queue_count = 0;
> +
> for (i = 0; i < ctrl_info->num_queue_groups; i++) {
> queue_group = &ctrl_info->queue_groups[i];
> -
> - rc = pqi_wait_until_queued_io_drained(ctrl_info, queue_group);
> - if (rc)
> - return rc;
> -
> for (path = 0; path < 2; path++) {
> iq_pi = queue_group->iq_pi_copy[path];
> + iq_ci = readl(queue_group->iq_ci[path]);
> + if (iq_ci != iq_pi)
> + nonempty_inbound_queue_count++;
> + }
> + }
>
> - while (1) {
> - iq_ci = readl(queue_group->iq_ci[path]);
> - if (iq_ci == iq_pi)
> - break;
> - pqi_check_ctrl_health(ctrl_info);
> - if (pqi_ctrl_offline(ctrl_info))
> - return -ENXIO;
> - usleep_range(1000, 2000);
> - }
> + return nonempty_inbound_queue_count;
> +}
> +
> +#define PQI_INBOUND_QUEUES_NONEMPTY_WARNING_TIMEOUT_SECS 10
> +
> +static int pqi_wait_until_inbound_queues_empty(struct pqi_ctrl_info *ctrl_info)
> +{
> + unsigned long start_jiffies;
> + unsigned long warning_timeout;
> + unsigned int queued_io_count;
> + unsigned int nonempty_inbound_queue_count;
> + bool displayed_warning;
> +
> + displayed_warning = false;
> + start_jiffies = jiffies;
> + warning_timeout = (PQI_INBOUND_QUEUES_NONEMPTY_WARNING_TIMEOUT_SECS * PQI_HZ) + start_jiffies;
> +
> + while (1) {
> + queued_io_count = pqi_queued_io_count(ctrl_info);
> + nonempty_inbound_queue_count = pqi_nonempty_inbound_queue_count(ctrl_info);
> + if (queued_io_count == 0 && nonempty_inbound_queue_count == 0)
> + break;
> + pqi_check_ctrl_health(ctrl_info);
> + if (pqi_ctrl_offline(ctrl_info))
> + return -ENXIO;
> + if (time_after(jiffies, warning_timeout)) {
> + dev_warn(&ctrl_info->pci_dev->dev,
> + "waiting %u seconds for queued I/O to drain (queued I/O count: %u; non-empty inbound queue count: %u)\n",
> + jiffies_to_msecs(jiffies - start_jiffies) / 1000, queued_io_count, nonempty_inbound_queue_count);
> + displayed_warning = true;
> + warning_timeout = (PQI_INBOUND_QUEUES_NONEMPTY_WARNING_TIMEOUT_SECS * PQI_HZ) + jiffies;
> }
> + usleep_range(1000, 2000);
> }
>
> + if (displayed_warning)
> + dev_warn(&ctrl_info->pci_dev->dev,
> + "queued I/O drained after waiting for %u seconds\n",
> + jiffies_to_msecs(jiffies - start_jiffies) / 1000);
> +
> return 0;
> }
>
> @@ -5922,7 +5949,7 @@ static int pqi_device_wait_for_pending_io(struct pqi_ctrl_info *ctrl_info,
> if (pqi_ctrl_offline(ctrl_info))
> return -ENXIO;
> msecs_waiting = jiffies_to_msecs(jiffies - start_jiffies);
> - if (msecs_waiting > timeout_msecs) {
> + if (msecs_waiting >= timeout_msecs) {
> dev_err(&ctrl_info->pci_dev->dev,
> "scsi %d:%d:%d:%d: timed out after %lu seconds waiting for %d outstanding command(s)\n",
> ctrl_info->scsi_host->host_no, device->bus, device->target,
> @@ -5957,6 +5984,7 @@ static int pqi_wait_for_lun_reset_completion(struct pqi_ctrl_info *ctrl_info,
> {
> int rc;
> unsigned int wait_secs;
> + int cmds_outstanding;
>
> wait_secs = 0;
>
> @@ -5974,11 +6002,10 @@ static int pqi_wait_for_lun_reset_completion(struct pqi_ctrl_info *ctrl_info,
> }
>
> wait_secs += PQI_LUN_RESET_POLL_COMPLETION_SECS;
> -
> + cmds_outstanding = atomic_read(&device->scsi_cmds_outstanding);
> dev_warn(&ctrl_info->pci_dev->dev,
> - "scsi %d:%d:%d:%d: waiting %u seconds for LUN reset to complete\n",
> - ctrl_info->scsi_host->host_no, device->bus, device->target, device->lun,
> - wait_secs);
> + "scsi %d:%d:%d:%d: waiting %u seconds for LUN reset to complete (%d command(s) outstanding)\n",
> + ctrl_info->scsi_host->host_no, device->bus, device->target, device->lun, wait_secs, cmds_outstanding);
> }
>
> return rc;
>