[PATCH 4.9 080/191] libata: Use per port sync for detach

Sasha Levin
2020-06-29T20:27:46Z

From: Kai-Heng Feng <kai.heng.feng@canonical.com>

[ Upstream commit b5292111de9bb70cba3489075970889765302136 ]

Commit 130f4caf145c ("libata: Ensure ata_port probe has completed before
detach") may cause system freeze during suspend.

Using async_synchronize_full() in PM callbacks is wrong, since async
callbacks that are already scheduled may wait for not-yet-scheduled
callbacks, causes a circular dependency.

Instead of using big hammer like async_synchronize_full(), use async
cookie to make sure port probe are synced, without affecting other
scheduled PM callbacks.

Fixes: 130f4caf145c ("libata: Ensure ata_port probe has completed before detach")
Suggested-by: John Garry <john.garry@huawei.com>
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Tested-by: John Garry <john.garry@huawei.com>
BugLink: https://bugs.launchpad.net/bugs/1867983
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/ata/libata-core.c | 11 +++++------
include/linux/libata.h | 3 +++
2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index ba0cffbd0bb6e..46bf7e9d00aba 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -57,7 +57,6 @@
#include <linux/workqueue.h>
#include <linux/scatterlist.h>
#include <linux/io.h>
-#include <linux/async.h>
#include <linux/log2.h>
#include <linux/slab.h>
#include <linux/glob.h>
@@ -6410,7 +6409,7 @@ int ata_host_register(struct ata_host *host, struct scsi_host_template *sht)
/* perform each probe asynchronously */
for (i = 0; i < host->n_ports; i++) {
struct ata_port *ap = host->ports[i];
- async_schedule(async_port_probe, ap);
+ ap->cookie = async_schedule(async_port_probe, ap);
}

return 0;
@@ -6550,11 +6549,11 @@ void ata_host_detach(struct ata_host *host)
{
int i;

- /* Ensure ata_port probe has completed */
- async_synchronize_full();
-
- for (i = 0; i < host->n_ports; i++)
+ for (i = 0; i < host->n_ports; i++) {
+ /* Ensure ata_port probe has completed */
+ async_synchronize_cookie(host->ports[i]->cookie + 1);
ata_port_detach(host->ports[i]);
+ }

/* the host is dead now, dissociate ACPI */
ata_acpi_dissociate(host);
diff --git a/include/linux/libata.h b/include/linux/libata.h
index cdfb67b22317b..780ccde2c3127 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -38,6 +38,7 @@
#include <linux/acpi.h>
#include <linux/cdrom.h>
#include <linux/sched.h>
+#include <linux/async.h>

/*
* Define if arch has non-standard setup. This is a _PCI_ standard
@@ -878,6 +879,8 @@ struct ata_port {
struct timer_list fastdrain_timer;
unsigned long fastdrain_cnt;

+ async_cookie_t cookie;
+
int em_message_type;
void *private_data;

--
2.25.1