2018-06-18 15:35:56

by Arnd Bergmann

[permalink] [raw]
Subject: [PATCH] scsi: lpfc: use monotonic timestamps for statistics

The get_seconds() function suffers from a possible overflow in 2038
or 2106, as well as jitter due to settimeofday or leap second updates,
and is deprecated.

As we are interested in elapsed time only, using ktime_get_seconds()
to read the CLOCK_MONOTONIC timebase is ideal here. This also lets us
remove the hack that tries to deal with get_seconds() going slightly
backwards, which cannot happen with montonic timestamps.

Signed-off-by: Arnd Bergmann <[email protected]>
---
drivers/scsi/lpfc/lpfc_attr.c | 10 ++--------
drivers/scsi/lpfc/lpfc_sli.c | 4 ++--
drivers/scsi/lpfc/lpfc_sli.h | 2 +-
3 files changed, 5 insertions(+), 11 deletions(-)

diff --git a/drivers/scsi/lpfc/lpfc_attr.c b/drivers/scsi/lpfc/lpfc_attr.c
index 729d343861f4..15c07481fe23 100644
--- a/drivers/scsi/lpfc/lpfc_attr.c
+++ b/drivers/scsi/lpfc/lpfc_attr.c
@@ -5891,7 +5891,6 @@ lpfc_get_stats(struct Scsi_Host *shost)
struct lpfc_lnk_stat * lso = &psli->lnk_stat_offsets;
LPFC_MBOXQ_t *pmboxq;
MAILBOX_t *pmb;
- unsigned long seconds;
int rc = 0;

/*
@@ -5992,12 +5991,7 @@ lpfc_get_stats(struct Scsi_Host *shost)

hs->dumped_frames = -1;

- seconds = get_seconds();
- if (seconds < psli->stats_start)
- hs->seconds_since_last_reset = seconds +
- ((unsigned long)-1 - psli->stats_start);
- else
- hs->seconds_since_last_reset = seconds - psli->stats_start;
+ hs->seconds_since_last_reset = ktime_get_seconds() - psli->stats_start;

mempool_free(pmboxq, phba->mbox_mem_pool);

@@ -6076,7 +6070,7 @@ lpfc_reset_stats(struct Scsi_Host *shost)
else
lso->link_events = (phba->fc_eventTag >> 1);

- psli->stats_start = get_seconds();
+ psli->stats_start = ktime_get_seconds();

mempool_free(pmboxq, phba->mbox_mem_pool);

diff --git a/drivers/scsi/lpfc/lpfc_sli.c b/drivers/scsi/lpfc/lpfc_sli.c
index 6f3c00a233ec..e6786a5db502 100644
--- a/drivers/scsi/lpfc/lpfc_sli.c
+++ b/drivers/scsi/lpfc/lpfc_sli.c
@@ -4591,7 +4591,7 @@ lpfc_sli_brdrestart_s3(struct lpfc_hba *phba)
spin_unlock_irq(&phba->hbalock);

memset(&psli->lnk_stat_offsets, 0, sizeof(psli->lnk_stat_offsets));
- psli->stats_start = get_seconds();
+ psli->stats_start = ktime_get_seconds();

/* Give the INITFF and Post time to settle. */
mdelay(100);
@@ -4638,7 +4638,7 @@ lpfc_sli_brdrestart_s4(struct lpfc_hba *phba)
spin_unlock_irq(&phba->hbalock);

memset(&psli->lnk_stat_offsets, 0, sizeof(psli->lnk_stat_offsets));
- psli->stats_start = get_seconds();
+ psli->stats_start = ktime_get_seconds();

/* Reset HBA AER if it was enabled, note hba_flag was reset above */
if (hba_aer_enabled)
diff --git a/drivers/scsi/lpfc/lpfc_sli.h b/drivers/scsi/lpfc/lpfc_sli.h
index 431754195505..80b191d73190 100644
--- a/drivers/scsi/lpfc/lpfc_sli.h
+++ b/drivers/scsi/lpfc/lpfc_sli.h
@@ -339,7 +339,7 @@ struct lpfc_sli {
struct lpfc_iocbq ** iocbq_lookup; /* array to lookup IOCB by IOTAG */
size_t iocbq_lookup_len; /* current lengs of the array */
uint16_t last_iotag; /* last allocated IOTAG */
- unsigned long stats_start; /* in seconds */
+ time64_t stats_start; /* in seconds */
struct lpfc_lnk_stat lnk_stat_offsets;
};

--
2.9.0



2018-06-25 07:50:52

by Johannes Thumshirn

[permalink] [raw]
Subject: Re: [PATCH] scsi: lpfc: use monotonic timestamps for statistics

Looks good,
Reviewed-by: Johannes Thumshirn <[email protected]>
--
Johannes Thumshirn Storage
[email protected] +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N?rnberg
GF: Felix Imend?rffer, Jane Smithard, Graham Norton
HRB 21284 (AG N?rnberg)
Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850

2018-06-26 18:17:17

by Martin K. Petersen

[permalink] [raw]
Subject: Re: [PATCH] scsi: lpfc: use monotonic timestamps for statistics


Arnd,

> The get_seconds() function suffers from a possible overflow in 2038 or
> 2106, as well as jitter due to settimeofday or leap second updates,
> and is deprecated.
>
> As we are interested in elapsed time only, using ktime_get_seconds()
> to read the CLOCK_MONOTONIC timebase is ideal here. This also lets us
> remove the hack that tries to deal with get_seconds() going slightly
> backwards, which cannot happen with montonic timestamps.

Applied to 4.19/scsi-queue. Thanks!

--
Martin K. Petersen Oracle Linux Engineering