[PATCH net-next] devlink: Execute devlink health recover as a work

Moshe Shemesh
2019-04-25T10:57:51Z

Different reporters have different rules in the driver and are being
created/destroyed during different stages of driver load/unload/running.
So during execution of a reporter recover the flow can go through
another reporter's destroy and create. Such flow leads to deadlock
trying to lock a mutex already held if the flow was triggered by devlink
recover command.
To avoid such deadlock, we execute the recover flow from a workqueue.
Once the recover work is done successfully the reporter health state and
recover counter are being updated.

Signed-off-by: Moshe Shemesh <moshe@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
---
include/net/devlink.h | 1 +
net/core/devlink.c | 70 +++++++++++++++++++++++++++++++++++----------------
2 files changed, 50 insertions(+), 21 deletions(-)

diff --git a/include/net/devlink.h b/include/net/devlink.h
index 4f5e416..820b327 100644
--- a/include/net/devlink.h
+++ b/include/net/devlink.h
@@ -32,6 +32,7 @@ struct devlink {
struct list_head region_list;
u32 snapshot_id;
struct list_head reporter_list;
+ struct workqueue_struct *reporters_wq;
struct devlink_dpipe_headers *dpipe_headers;
const struct devlink_ops *ops;
struct device *dev;
diff --git a/net/core/devlink.c b/net/core/devlink.c
index 7b91605..8ee380e 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -4422,6 +4422,7 @@ struct devlink_health_reporter {
u64 error_count;
u64 recovery_count;
u64 last_recovery_ts;
+ struct work_struct recover_work;
};

void *
@@ -4443,6 +4444,40 @@ struct devlink_health_reporter {
return NULL;
}

+static int
+devlink_health_reporter_recover(struct devlink_health_reporter *reporter,
+ void *priv_ctx)
+{
+ int err;
+
+ if (!reporter->ops->recover)
+ return -EOPNOTSUPP;
+
+ err = reporter->ops->recover(reporter, priv_ctx);
+ if (err)
+ return err;
+
+ reporter->recovery_count++;
+ reporter->health_state = DEVLINK_HEALTH_REPORTER_STATE_HEALTHY;
+ reporter->last_recovery_ts = jiffies;
+
+ trace_devlink_health_reporter_state_update(reporter->devlink,
+ reporter->ops->name,
+ reporter->health_state);
+ return 0;
+}
+
+static void
+devlink_health_reporter_recover_work(struct work_struct *work)
+{
+ struct devlink_health_reporter *reporter;
+
+ reporter = container_of(work, struct devlink_health_reporter,
+ recover_work);
+
+ devlink_health_reporter_recover(reporter, NULL);
+}
+
/**
* devlink_health_reporter_create - create devlink health reporter
*
@@ -4483,6 +4518,8 @@ struct devlink_health_reporter *
reporter->devlink = devlink;
reporter->graceful_period = graceful_period;
reporter->auto_recover = auto_recover;
+ INIT_WORK(&reporter->recover_work,
+ devlink_health_reporter_recover_work);
mutex_init(&reporter->dump_lock);
list_add_tail(&reporter->list, &devlink->reporter_list);
unlock:
@@ -4505,6 +4542,7 @@ struct devlink_health_reporter *
mutex_unlock(&reporter->devlink->lock);
if (reporter->dump_fmsg)
devlink_fmsg_free(reporter->dump_fmsg);
+ cancel_work_sync(&reporter->recover_work);
kfree(reporter);
}
EXPORT_SYMBOL_GPL(devlink_health_reporter_destroy);
@@ -4526,26 +4564,6 @@ struct devlink_health_reporter *
}
EXPORT_SYMBOL_GPL(devlink_health_reporter_state_update);

-static int
-devlink_health_reporter_recover(struct devlink_health_reporter *reporter,
- void *priv_ctx)
-{
- int err;
-
- if (!reporter->ops->recover)
- return -EOPNOTSUPP;
-
- err = reporter->ops->recover(reporter, priv_ctx);
- if (err)
- return err;
-
- reporter->recovery_count++;
- reporter->health_state = DEVLINK_HEALTH_REPORTER_STATE_HEALTHY;
- reporter->last_recovery_ts = jiffies;
-
- return 0;
-}
-
static void
devlink_health_dump_clear(struct devlink_health_reporter *reporter)
{
@@ -4813,7 +4831,11 @@ static int devlink_nl_cmd_health_reporter_recover_doit(struct sk_buff *skb,
if (!reporter)
return -EINVAL;

- return devlink_health_reporter_recover(reporter, NULL);
+ if (!reporter->ops->recover)
+ return -EOPNOTSUPP;
+
+ queue_work(devlink->reporters_wq, &reporter->recover_work);
+ return 0;
}

static int devlink_nl_cmd_health_reporter_diagnose_doit(struct sk_buff *skb,
@@ -5234,6 +5256,11 @@ struct devlink *devlink_alloc(const struct devlink_ops *ops, size_t priv_size)
INIT_LIST_HEAD(&devlink->param_list);
INIT_LIST_HEAD(&devlink->region_list);
INIT_LIST_HEAD(&devlink->reporter_list);
+ devlink->reporters_wq = create_singlethread_workqueue("devlink_reporters");
+ if (!devlink->reporters_wq) {
+ kfree(devlink);
+ return NULL;
+ }
mutex_init(&devlink->lock);
return devlink;
}
@@ -5278,6 +5305,7 @@ void devlink_unregister(struct devlink *devlink)
void devlink_free(struct devlink *devlink)
{
mutex_destroy(&devlink->lock);
+ destroy_workqueue(devlink->reporters_wq);
WARN_ON(!list_empty(&devlink->reporter_list));
WARN_ON(!list_empty(&devlink->region_list));
WARN_ON(!list_empty(&devlink->param_list));
--
1.8.3.1