On Mon, 2015-08-10 at 12:09 -0500, Matthew R. Ochs wrote:
> Introduce support for enhanced I/O error handling.
This needs more description of what you're doing. What's the overall
approach? There seems to be a new limbo queue thats created stall things
while the device is in error state. That should be described here.
> Signed-off-by: Matthew R. Ochs <mrochs@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Manoj N. Kumar <manoj@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/scsi/cxlflash/Kconfig | 2 +-
> drivers/scsi/cxlflash/common.h | 11 ++-
> drivers/scsi/cxlflash/main.c | 166 ++++++++++++++++++++++++++++++++++++++---
> drivers/scsi/cxlflash/main.h | 4 +
> 4 files changed, 170 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/scsi/cxlflash/Kconfig b/drivers/scsi/cxlflash/Kconfig
> index c707508..c052104 100644
> --- a/drivers/scsi/cxlflash/Kconfig
> +++ b/drivers/scsi/cxlflash/Kconfig
> @@ -4,7 +4,7 @@
>
> config CXLFLASH
> tristate "Support for IBM CAPI Flash"
> - depends on PCI && SCSI && CXL
> + depends on PCI && SCSI && CXL && EEH
> default m
> help
> Allows CAPI Accelerated IO to Flash
> diff --git a/drivers/scsi/cxlflash/common.h b/drivers/scsi/cxlflash/common.h
> index fe86bfe..7e663f4 100644
> --- a/drivers/scsi/cxlflash/common.h
> +++ b/drivers/scsi/cxlflash/common.h
> @@ -76,6 +76,12 @@ enum cxlflash_init_state {
> INIT_STATE_SCSI
> };
>
> +enum cxlflash_state {
> + STATE_NORMAL, /* Normal running state, everything good */
> + STATE_LIMBO, /* Limbo running state, trying to reset/recover */
> + STATE_FAILTERM /* Failed/terminating state, error out users/threads */
> +};
> +
> /*
> * Each context has its own set of resource handles that is visible
> * only from that context.
> @@ -91,8 +97,6 @@ struct cxlflash_cfg {
>
> ulong cxlflash_regs_pci;
>
> - wait_queue_head_t eeh_waitq;
> -
> struct work_struct work_q;
> enum cxlflash_init_state init_state;
> enum cxlflash_lr_state lr_state;
> @@ -105,7 +109,8 @@ struct cxlflash_cfg {
>
> wait_queue_head_t tmf_waitq;
> bool tmf_active;
> - u8 err_recovery_active:1;
> + wait_queue_head_t limbo_waitq;
> + enum cxlflash_state state;
> };
>
> struct afu_cmd {
> diff --git a/drivers/scsi/cxlflash/main.c b/drivers/scsi/cxlflash/main.c
> index 76a7286..18359d4 100644
> --- a/drivers/scsi/cxlflash/main.c
> +++ b/drivers/scsi/cxlflash/main.c
> @@ -380,6 +380,18 @@ static int cxlflash_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scp)
> }
> spin_unlock_irqrestore(&cfg->tmf_waitq.lock, lock_flags);
>
> + switch (cfg->state) {
> + case STATE_LIMBO:
> + pr_debug_ratelimited("%s: device in limbo!\n", __func__);
> + rc = SCSI_MLQUEUE_HOST_BUSY;
So if the client gets BUSY, it should retry until it suceeds or gets a terminal
failure?
> + goto out;
> + case STATE_FAILTERM:
> + pr_debug_ratelimited("%s: device has failed!\n", __func__);
> + goto error;
error is only used here, so there is no need for a goto.
> + default:
> + break;
> + }
> +
> cmd = cxlflash_cmd_checkout(afu);
> if (unlikely(!cmd)) {
> pr_err("%s: could not get a free command\n", __func__);
> @@ -428,6 +440,10 @@ static int cxlflash_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scp)
>
> out:
> return rc;
> +error:
> + scp->result = (DID_NO_CONNECT << 16);
> + scp->scsi_done(scp);
> + return 0;
0 is success. That doesn't seem right for an error.
> }
>
> /**
> @@ -455,9 +471,21 @@ static int cxlflash_eh_device_reset_handler(struct scsi_cmnd *scp)
> get_unaligned_be32(&((u32 *)scp->cmnd)[2]),
> get_unaligned_be32(&((u32 *)scp->cmnd)[3]));
>
> - rcr = send_tmf(afu, scp, TMF_LUN_RESET);
> - if (unlikely(rcr))
> + switch (cfg->state) {
> + case STATE_NORMAL:
> + rcr = send_tmf(afu, scp, TMF_LUN_RESET);
> + if (unlikely(rcr))
> + rc = FAILED;
> + break;
> + case STATE_LIMBO:
> + wait_event(cfg->limbo_waitq, cfg->state != STATE_LIMBO);
So we wait here till we are our of limbo?
> + if (cfg->state == STATE_NORMAL)
> + break;
> + /* fall through */
> + default:
> rc = FAILED;
> + break;
> + }
>
> pr_debug("%s: returning rc=%d\n", __func__, rc);
> return rc;
> @@ -487,11 +515,27 @@ static int cxlflash_eh_host_reset_handler(struct scsi_cmnd *scp)
> get_unaligned_be32(&((u32 *)scp->cmnd)[2]),
> get_unaligned_be32(&((u32 *)scp->cmnd)[3]));
>
> - rcr = cxlflash_afu_reset(cfg);
> - if (rcr == 0)
> - rc = SUCCESS;
> - else
> + switch (cfg->state) {
> + case STATE_NORMAL:
> + cfg->state = STATE_LIMBO;
> + scsi_block_requests(cfg->host);
> +
> + rcr = cxlflash_afu_reset(cfg);
> + if (!rcr)
> + rc = FAILED;
This is some sort of recovery once we get back into normal state? Can you
comment what you're doing here?
> + cfg->state = STATE_NORMAL;
> + wake_up_all(&cfg->limbo_waitq);
> + scsi_unblock_requests(cfg->host);
Now we actually go to normal?
> + break;
> + case STATE_LIMBO:
> + wait_event(cfg->limbo_waitq, cfg->state != STATE_LIMBO);
Wait here till we are out of limbo? What happens if that never occurs?
> + if (cfg->state == STATE_NORMAL)
> + break;
> + /* fall through */
> + default:
> rc = FAILED;
> + break;
> + }
>
> pr_debug("%s: returning rc=%d\n", __func__, rc);
> return rc;
> @@ -642,7 +686,7 @@ static void cxlflash_wait_for_pci_err_recovery(struct cxlflash_cfg *cfg)
> struct pci_dev *pdev = cfg->dev;
>
> if (pci_channel_offline(pdev))
> - wait_event_timeout(cfg->eeh_waitq,
> + wait_event_timeout(cfg->limbo_waitq,
> !pci_channel_offline(pdev),
> CXLFLASH_PCI_ERROR_RECOVERY_TIMEOUT);
> }
> @@ -825,6 +869,8 @@ static void cxlflash_remove(struct pci_dev *pdev)
> !cfg->tmf_active);
> spin_unlock_irqrestore(&cfg->tmf_waitq.lock, lock_flags);
>
> + cfg->state = STATE_FAILTERM;
> +
> switch (cfg->init_state) {
> case INIT_STATE_SCSI:
> scsi_remove_host(cfg->host);
> @@ -1879,6 +1925,8 @@ static int init_afu(struct cxlflash_cfg *cfg)
> struct afu *afu = cfg->afu;
> struct device *dev = &cfg->dev->dev;
>
> + cxl_perst_reloads_same_image(cfg->cxl_afu, true);
> +
> rc = init_mc(cfg);
> if (rc) {
> dev_err(dev, "%s: call to init_mc failed, rc=%d!\n",
> @@ -2021,6 +2069,12 @@ void cxlflash_wait_resp(struct afu *afu, struct afu_cmd *cmd)
> * the sync. This design point requires calling threads to not be on interrupt
> * context due to the possibility of sleeping during concurrent sync operations.
> *
> + * AFU sync operations are only necessary and allowed when the device is
> + * operating normally. When not operating normally, sync requests can occur as
> + * part of cleaning up resources associated with an adapter prior to removal.
> + * In this scenario, these requests are simply ignored (safe due to the AFU
> + * going away).
> + *
What about if we are in limbo state and it comes back?
> * Return:
> * 0 on success
> * -1 on failure
> @@ -2028,11 +2082,17 @@ void cxlflash_wait_resp(struct afu *afu, struct afu_cmd *cmd)
> int cxlflash_afu_sync(struct afu *afu, ctx_hndl_t ctx_hndl_u,
> res_hndl_t res_hndl_u, u8 mode)
> {
> + struct cxlflash_cfg *cfg = afu->parent;
> struct afu_cmd *cmd = NULL;
> int rc = 0;
> int retry_cnt = 0;
> static DEFINE_MUTEX(sync_active);
>
> + if (cfg->state != STATE_NORMAL) {
> + pr_debug("%s: Sync not required! (%u)\n", __func__, cfg->state);
> + return 0;
> + }
> +
> mutex_lock(&sync_active);
> retry:
> cmd = cxlflash_cmd_checkout(afu);
> @@ -2122,6 +2182,11 @@ static void cxlflash_worker_thread(struct work_struct *work)
> int port;
> ulong lock_flags;
>
> + /* Avoid MMIO if the device has failed */
> +
> + if (cfg->state != STATE_NORMAL)
> + return;
> +
> spin_lock_irqsave(cfg->host->host_lock, lock_flags);
>
> if (cfg->lr_state == LINK_RESET_REQUIRED) {
> @@ -2200,10 +2265,9 @@ static int cxlflash_probe(struct pci_dev *pdev,
> cfg->dev = pdev;
> cfg->dev_id = (struct pci_device_id *)dev_id;
> cfg->mcctx = NULL;
> - cfg->err_recovery_active = 0;
>
> init_waitqueue_head(&cfg->tmf_waitq);
> - init_waitqueue_head(&cfg->eeh_waitq);
> + init_waitqueue_head(&cfg->limbo_waitq);
>
> INIT_WORK(&cfg->work_q, cxlflash_worker_thread);
> cfg->lr_state = LINK_RESET_INVALID;
> @@ -2259,6 +2323,89 @@ out_remove:
> goto out;
> }
>
> +/**
> + * cxlflash_pci_error_detected() - called when a PCI error is detected
> + * @pdev: PCI device struct.
> + * @state: PCI channel state.
> + *
> + * Return: PCI_ERS_RESULT_NEED_RESET or PCI_ERS_RESULT_DISCONNECT
> + */
> +static pci_ers_result_t cxlflash_pci_error_detected(struct pci_dev *pdev,
> + pci_channel_state_t state)
> +{
> + struct cxlflash_cfg *cfg = pci_get_drvdata(pdev);
> +
> + pr_debug("%s: pdev=%p state=%u\n", __func__, pdev, state);
> +
> + switch (state) {
> + case pci_channel_io_frozen:
> + cfg->state = STATE_LIMBO;
> +
> + /* Turn off legacy I/O */
> + scsi_block_requests(cfg->host);
> +
> + term_mc(cfg, UNDO_START);
> + stop_afu(cfg);
> +
> + return PCI_ERS_RESULT_NEED_RESET;
> + case pci_channel_io_perm_failure:
> + cfg->state = STATE_FAILTERM;
> + wake_up_all(&cfg->limbo_waitq);
> + scsi_unblock_requests(cfg->host);
> + return PCI_ERS_RESULT_DISCONNECT;
> + default:
> + break;
> + }
> + return PCI_ERS_RESULT_NEED_RESET;
> +}
> +
> +/**
> + * cxlflash_pci_slot_reset() - called when PCI slot has been reset
> + * @pdev: PCI device struct.
> + *
> + * This routine is called by the pci error recovery code after the PCI
> + * slot has been reset, just before we should resume normal operations.
> + *
> + * Return: PCI_ERS_RESULT_RECOVERED or PCI_ERS_RESULT_DISCONNECT
> + */
> +static pci_ers_result_t cxlflash_pci_slot_reset(struct pci_dev *pdev)
> +{
> + int rc = 0;
> + struct cxlflash_cfg *cfg = pci_get_drvdata(pdev);
> + struct device *dev = &cfg->dev->dev;
> +
> + pr_debug("%s: pdev=%p\n", __func__, pdev);
> +
> + rc = init_afu(cfg);
> + if (unlikely(rc)) {
> + dev_err(dev, "%s: EEH recovery failed! (%d)\n", __func__, rc);
> + return PCI_ERS_RESULT_DISCONNECT;
> + }
> +
> + return PCI_ERS_RESULT_RECOVERED;
> +}
> +
> +/**
> + * cxlflash_pci_resume() - called when normal operation can resume
> + * @pdev: PCI device struct
> + */
> +static void cxlflash_pci_resume(struct pci_dev *pdev)
> +{
> + struct cxlflash_cfg *cfg = pci_get_drvdata(pdev);
> +
> + pr_debug("%s: pdev=%p\n", __func__, pdev);
> +
> + cfg->state = STATE_NORMAL;
> + wake_up_all(&cfg->limbo_waitq);
> + scsi_unblock_requests(cfg->host);
> +}
> +
> +static const struct pci_error_handlers cxlflash_err_handler = {
> + .error_detected = cxlflash_pci_error_detected,
> + .slot_reset = cxlflash_pci_slot_reset,
> + .resume = cxlflash_pci_resume,
> +};
> +
> /*
> * PCI device structure
> */
> @@ -2267,6 +2414,7 @@ static struct pci_driver cxlflash_driver = {
> .id_table = cxlflash_pci_table,
> .probe = cxlflash_probe,
> .remove = cxlflash_remove,
> + .err_handler = &cxlflash_err_handler,
> };
>
> /**
> diff --git a/drivers/scsi/cxlflash/main.h b/drivers/scsi/cxlflash/main.h
> index 7f890cc..7232536 100644
> --- a/drivers/scsi/cxlflash/main.h
> +++ b/drivers/scsi/cxlflash/main.h
> @@ -101,4 +101,8 @@ struct asyc_intr_info {
> #define LINK_RESET 0x02
> };
>
> +#ifndef CONFIG_CXL_EEH
> +#define cxl_perst_reloads_same_image(_a, _b) do { } while (0)
> +#endif
> +
> #endif /* _CXLFLASH_MAIN_H */
--
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