linux-kernel - [PATCH 5/5] acpi, nfit: limit ->flush

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Date:   Fri, 14 Apr 2017 09:58:38 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     linux-nvdimm@...ts.01.org
Cc:     linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
        vishal.l.verma@...el.com
Subject: [PATCH 5/5] acpi, nfit: limit ->flush_probe() to initialization work

The nvdimm probe flushing mechanism gives userspace a sync point where
it knows all asynchronous driver probe sequences have completed.
However, it need not wait for other asynchronous actions, like
on-demand address-range-scrub. Track the init work separately from other
work in the workqueue, and only flush the former.

Signed-off-by: Dan Williams <dan.j.williams@...el.com>
---
 drivers/acpi/nfit/core.c |   13 ++++++++++---
 drivers/acpi/nfit/nfit.h |    1 +
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index 06738df477db..17cac9d369e0 100644
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -738,7 +738,7 @@ static void nfit_mem_init_bdw(struct acpi_nfit_desc *acpi_desc,
 	}
 }
 
-static int nfit_mem_dcr_init(struct acpi_nfit_desc *acpi_desc,
+static int __nfit_mem_init(struct acpi_nfit_desc *acpi_desc,
 		struct acpi_nfit_system_address *spa)
 {
 	struct nfit_mem *nfit_mem, *found;
@@ -898,7 +898,7 @@ static int nfit_mem_init(struct acpi_nfit_desc *acpi_desc)
 	 * BDWs are optional.
 	 */
 	list_for_each_entry(nfit_spa, &acpi_desc->spas, list) {
-		rc = nfit_mem_dcr_init(acpi_desc, nfit_spa->spa);
+		rc = __nfit_mem_init(acpi_desc, nfit_spa->spa);
 		if (rc)
 			return rc;
 	}
@@ -908,7 +908,7 @@ static int nfit_mem_init(struct acpi_nfit_desc *acpi_desc)
 	 * SPA entries above. Find and register all the unmapped DIMMs
 	 * for reporting and recovery purposes.
 	 */
-	rc = nfit_mem_dcr_init(acpi_desc, NULL);
+	rc = __nfit_mem_init(acpi_desc, NULL);
 	if (rc)
 		return rc;
 
@@ -2568,6 +2568,7 @@ static void acpi_nfit_scrub(struct work_struct *work)
 			acpi_nfit_register_region(acpi_desc, nfit_spa);
 		}
 	}
+	acpi_desc->init_complete = 1;
 
 	list_for_each_entry(nfit_spa, &acpi_desc->spas, list)
 		acpi_nfit_async_scrub(acpi_desc, nfit_spa);
@@ -2771,6 +2772,12 @@ static int acpi_nfit_flush_probe(struct nvdimm_bus_descriptor *nd_desc)
 	device_lock(dev);
 	device_unlock(dev);
 
+	/* bounce the init_mutex to make init_complete valid */
+	mutex_lock(&acpi_desc->init_mutex);
+	mutex_unlock(&acpi_desc->init_mutex);
+	if (acpi_desc->init_complete)
+		return 0;
+
 	/*
 	 * Scrub work could take 10s of seconds, userspace may give up so we
 	 * need to be interruptible while waiting.
diff --git a/drivers/acpi/nfit/nfit.h b/drivers/acpi/nfit/nfit.h
index fc29c2e9832e..256829597585 100644
--- a/drivers/acpi/nfit/nfit.h
+++ b/drivers/acpi/nfit/nfit.h
@@ -163,6 +163,7 @@ struct acpi_nfit_desc {
 	unsigned int scrub_count;
 	unsigned int scrub_mode;
 	unsigned int cancel:1;
+	unsigned int init_complete:1;
 	unsigned long dimm_cmd_force_en;
 	unsigned long bus_cmd_force_en;
 	int (*blk_do_io)(struct nd_blk_region *ndbr, resource_size_t dpa,