From 5479b2757f26fe9908fc341d105b2097fe820b6f Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Wed, 13 Feb 2019 09:04:07 -0800 Subject: nfit/ars: Allow root to busy-poll the ARS state machine The ARS implementation implements exponential back-off on the poll interval to prevent high-frequency access to the DIMM / platform interface. Depending on when the ARS completes the poll interval may exceed the completion event by minutes. Allow root to reset the timeout each time it probes the status. A one-second timeout is still enforced, but root can otherwise can control the poll interval. Fixes: bc6ba8085842 ("nfit, address-range-scrub: rework and simplify ARS...") Cc: Reported-by: Erwin Tsaur Reviewed-by: Toshi Kani Signed-off-by: Dan Williams --- drivers/acpi/nfit/core.c | 8 ++++++++ drivers/acpi/nfit/nfit.h | 1 + 2 files changed, 9 insertions(+) (limited to 'drivers/acpi') diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c index 90312892093e..629cf91649d2 100644 --- a/drivers/acpi/nfit/core.c +++ b/drivers/acpi/nfit/core.c @@ -1333,6 +1333,13 @@ static ssize_t scrub_show(struct device *dev, busy = test_bit(ARS_BUSY, &acpi_desc->scrub_flags) && !test_bit(ARS_CANCEL, &acpi_desc->scrub_flags); rc = sprintf(buf, "%d%s", acpi_desc->scrub_count, busy ? "+\n" : "\n"); + /* Allow an admin to poll the busy state at a higher rate */ + if (busy && capable(CAP_SYS_RAWIO) && !test_and_set_bit(ARS_POLL, + &acpi_desc->scrub_flags)) { + acpi_desc->scrub_tmo = 1; + mod_delayed_work(nfit_wq, &acpi_desc->dwork, HZ); + } + mutex_unlock(&acpi_desc->init_mutex); device_unlock(dev); return rc; @@ -3187,6 +3194,7 @@ static void acpi_nfit_scrub(struct work_struct *work) else notify_ars_done(acpi_desc); memset(acpi_desc->ars_status, 0, acpi_desc->max_ars); + clear_bit(ARS_POLL, &acpi_desc->scrub_flags); mutex_unlock(&acpi_desc->init_mutex); } diff --git a/drivers/acpi/nfit/nfit.h b/drivers/acpi/nfit/nfit.h index 897ce10192a0..d14bad687fb8 100644 --- a/drivers/acpi/nfit/nfit.h +++ b/drivers/acpi/nfit/nfit.h @@ -213,6 +213,7 @@ struct nfit_mem { enum scrub_flags { ARS_BUSY, ARS_CANCEL, + ARS_POLL, }; struct acpi_nfit_desc { -- cgit