IB/core: lock client data with lists_rwsem

An ib_client callback that is called with the lists_rwsem locked only for
read is protected from changes to the IB client lists, but not from
ib_unregister_device() freeing its client data. This is because
ib_unregister_device() will remove the device from the device list with
lists_rwsem locked for write, but perform the rest of the cleanup,
including the call to remove() without that lock.

Mark client data that is undergoing de-registration with a new going_down
flag in the client data context. Lock the client data list with lists_rwsem
for write in addition to using the spinlock, so that functions calling the
callback would be able to lock only lists_rwsem for read and let callbacks
sleep.

Since ib_unregister_client() now marks the client data context, no need for
remove() to search the context again, so pass the client data directly to
remove() callbacks.

Reviewed-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: Haggai Eran <haggaie@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

10 files changed, 67 insertions, 35 deletions

diff --git a/drivers/infiniband/core/cache.c b/drivers/infiniband/core/cache.c
index 871da832d016..c93af66cc091 100644
--- a/drivers/infiniband/core/cache.c
+++ b/drivers/infiniband/core/cache.c
@@ -394,7 +394,7 @@ err:
 	kfree(device->cache.lmc_cache);
 }
 
-static void ib_cache_cleanup_one(struct ib_device *device)
+static void ib_cache_cleanup_one(struct ib_device *device, void *client_data)
 {
 	int p;
 
diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c
index 3a972ebf3c0d..82d5c4362aa8 100644
--- a/drivers/infiniband/core/cm.c
+++ b/drivers/infiniband/core/cm.c
@@ -58,7 +58,7 @@ MODULE_DESCRIPTION("InfiniBand CM");
 MODULE_LICENSE("Dual BSD/GPL");
 
 static void cm_add_one(struct ib_device *device);
-static void cm_remove_one(struct ib_device *device);
+static void cm_remove_one(struct ib_device *device, void *client_data);
 
 static struct ib_client cm_client = {
 	.name   = "cm",
@@ -3886,9 +3886,9 @@ free:
 	kfree(cm_dev);
 }
 
-static void cm_remove_one(struct ib_device *ib_device)
+static void cm_remove_one(struct ib_device *ib_device, void *client_data)
 {
-	struct cm_device *cm_dev;
+	struct cm_device *cm_dev = client_data;
 	struct cm_port *port;
 	struct ib_port_modify port_modify = {
 		.clr_port_cap_mask = IB_PORT_CM_SUP
@@ -3896,7 +3896,6 @@ static void cm_remove_one(struct ib_device *ib_device)
 	unsigned long flags;
 	int i;
 
-	cm_dev = ib_get_client_data(ib_device, &cm_client);
 	if (!cm_dev)
 		return;
 
diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 4e72e4c16cfe..9664131c4eeb 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -94,7 +94,7 @@ const char *rdma_event_msg(enum rdma_cm_event_type event)
 EXPORT_SYMBOL(rdma_event_msg);
 
 static void cma_add_one(struct ib_device *device);
-static void cma_remove_one(struct ib_device *device);
+static void cma_remove_one(struct ib_device *device, void *client_data);
 
 static struct ib_client cma_client = {
 	.name   = "cma",
@@ -3554,11 +3554,10 @@ static void cma_process_remove(struct cma_device *cma_dev)
 	wait_for_completion(&cma_dev->comp);
 }
 
-static void cma_remove_one(struct ib_device *device)
+static void cma_remove_one(struct ib_device *device, void *client_data)
 {
-	struct cma_device *cma_dev;
+	struct cma_device *cma_dev = client_data;
 
-	cma_dev = ib_get_client_data(device, &cma_client);
 	if (!cma_dev)
 		return;
 
diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
index 0c8fa781538b..ce317e623862 100644
--- a/drivers/infiniband/core/device.c
+++ b/drivers/infiniband/core/device.c
@@ -50,6 +50,9 @@ struct ib_client_data {
 	struct list_head  list;
 	struct ib_client *client;
 	void *            data;
+	/* The device or client is going down. Do not call client or device
+	 * callbacks other than remove(). */
+	bool		  going_down;
 };
 
 struct workqueue_struct *ib_wq;
@@ -69,6 +72,8 @@ static LIST_HEAD(client_list);
  * to the lists must be done with a write lock. A special case is when the
  * device_mutex is locked. In this case locking the lists for read access is
  * not necessary as the device_mutex implies it.
+ *
+ * lists_rwsem also protects access to the client data list.
  */
 static DEFINE_MUTEX(device_mutex);
 static DECLARE_RWSEM(lists_rwsem);
@@ -210,10 +215,13 @@ static int add_client_context(struct ib_device *device, struct ib_client *client
 
 	context->client = client;
 	context->data   = NULL;
+	context->going_down = false;
 
+	down_write(&lists_rwsem);
 	spin_lock_irqsave(&device->client_data_lock, flags);
 	list_add(&context->list, &device->client_data_list);
 	spin_unlock_irqrestore(&device->client_data_lock, flags);
+	up_write(&lists_rwsem);
 
 	return 0;
 }
@@ -339,7 +347,6 @@ EXPORT_SYMBOL(ib_register_device);
  */
 void ib_unregister_device(struct ib_device *device)
 {
-	struct ib_client *client;
 	struct ib_client_data *context, *tmp;
 	unsigned long flags;
 
@@ -347,20 +354,29 @@ void ib_unregister_device(struct ib_device *device)
 
 	down_write(&lists_rwsem);
 	list_del(&device->core_list);
-	up_write(&lists_rwsem);
+	spin_lock_irqsave(&device->client_data_lock, flags);
+	list_for_each_entry_safe(context, tmp, &device->client_data_list, list)
+		context->going_down = true;
+	spin_unlock_irqrestore(&device->client_data_lock, flags);
+	downgrade_write(&lists_rwsem);
 
-	list_for_each_entry_reverse(client, &client_list, list)
-		if (client->remove)
-			client->remove(device);
+	list_for_each_entry_safe(context, tmp, &device->client_data_list,
+				 list) {
+		if (context->client->remove)
+			context->client->remove(device, context->data);
+	}
+	up_read(&lists_rwsem);
 
 	mutex_unlock(&device_mutex);
 
 	ib_device_unregister_sysfs(device);
 
+	down_write(&lists_rwsem);
 	spin_lock_irqsave(&device->client_data_lock, flags);
 	list_for_each_entry_safe(context, tmp, &device->client_data_list, list)
 		kfree(context);
 	spin_unlock_irqrestore(&device->client_data_lock, flags);
+	up_write(&lists_rwsem);
 
 	device->reg_state = IB_DEV_UNREGISTERED;
 }
@@ -420,16 +436,35 @@ void ib_unregister_client(struct ib_client *client)
 	up_write(&lists_rwsem);
 
 	list_for_each_entry(device, &device_list, core_list) {
-		if (client->remove)
-			client->remove(device);
+		struct ib_client_data *found_context = NULL;
 
+		down_write(&lists_rwsem);
 		spin_lock_irqsave(&device->client_data_lock, flags);
 		list_for_each_entry_safe(context, tmp, &device->client_data_list, list)
 			if (context->client == client) {
-				list_del(&context->list);
-				kfree(context);
+				context->going_down = true;
+				found_context = context;
+				break;
 			}
 		spin_unlock_irqrestore(&device->client_data_lock, flags);
+		up_write(&lists_rwsem);
+
+		if (client->remove)
+			client->remove(device, found_context ?
+					       found_context->data : NULL);
+
+		if (!found_context) {
+			pr_warn("No client context found for %s/%s\n",
+				device->name, client->name);
+			continue;
+		}
+
+		down_write(&lists_rwsem);
+		spin_lock_irqsave(&device->client_data_lock, flags);
+		list_del(&found_context->list);
+		kfree(found_context);
+		spin_unlock_irqrestore(&device->client_data_lock, flags);
+		up_write(&lists_rwsem);
 	}
 
 	mutex_unlock(&device_mutex);
diff --git a/drivers/infiniband/core/mad.c b/drivers/infiniband/core/mad.c
index 786fc51bf04b..66b4b3eb8f67 100644
--- a/drivers/infiniband/core/mad.c
+++ b/drivers/infiniband/core/mad.c
@@ -3335,7 +3335,7 @@ error:
 	}
 }
 
-static void ib_mad_remove_device(struct ib_device *device)
+static void ib_mad_remove_device(struct ib_device *device, void *client_data)
 {
 	int i;
 
diff --git a/drivers/infiniband/core/multicast.c b/drivers/infiniband/core/multicast.c
index 2cb865c7ce7a..d38d8b2b2979 100644
--- a/drivers/infiniband/core/multicast.c
+++ b/drivers/infiniband/core/multicast.c
@@ -43,7 +43,7 @@
 #include "sa.h"
 
 static void mcast_add_one(struct ib_device *device);
-static void mcast_remove_one(struct ib_device *device);
+static void mcast_remove_one(struct ib_device *device, void *client_data);
 
 static struct ib_client mcast_client = {
 	.name   = "ib_multicast",
@@ -840,13 +840,12 @@ static void mcast_add_one(struct ib_device *device)
 	ib_register_event_handler(&dev->event_handler);
 }
 
-static void mcast_remove_one(struct ib_device *device)
+static void mcast_remove_one(struct ib_device *device, void *client_data)
 {
-	struct mcast_device *dev;
+	struct mcast_device *dev = client_data;
 	struct mcast_port *port;
 	int i;
 
-	dev = ib_get_client_data(device, &mcast_client);
 	if (!dev)
 		return;
 
diff --git a/drivers/infiniband/core/sa_query.c b/drivers/infiniband/core/sa_query.c
index ca919f429666..d40be3673b79 100644
--- a/drivers/infiniband/core/sa_query.c
+++ b/drivers/infiniband/core/sa_query.c
@@ -107,7 +107,7 @@ struct ib_sa_mcmember_query {
 };
 
 static void ib_sa_add_one(struct ib_device *device);
-static void ib_sa_remove_one(struct ib_device *device);
+static void ib_sa_remove_one(struct ib_device *device, void *client_data);
 
 static struct ib_client sa_client = {
 	.name   = "sa",
@@ -1221,9 +1221,9 @@ free:
 	return;
 }
 
-static void ib_sa_remove_one(struct ib_device *device)
+static void ib_sa_remove_one(struct ib_device *device, void *client_data)
 {
-	struct ib_sa_device *sa_dev = ib_get_client_data(device, &sa_client);
+	struct ib_sa_device *sa_dev = client_data;
 	int i;
 
 	if (!sa_dev)
diff --git a/drivers/infiniband/core/ucm.c b/drivers/infiniband/core/ucm.c
index 009481073644..8cde48b96f19 100644
--- a/drivers/infiniband/core/ucm.c
+++ b/drivers/infiniband/core/ucm.c
@@ -109,7 +109,7 @@ enum {
 #define IB_UCM_BASE_DEV MKDEV(IB_UCM_MAJOR, IB_UCM_BASE_MINOR)
 
 static void ib_ucm_add_one(struct ib_device *device);
-static void ib_ucm_remove_one(struct ib_device *device);
+static void ib_ucm_remove_one(struct ib_device *device, void *client_data);
 
 static struct ib_client ucm_client = {
 	.name   = "ucm",
@@ -1310,9 +1310,9 @@ err:
 	return;
 }
 
-static void ib_ucm_remove_one(struct ib_device *device)
+static void ib_ucm_remove_one(struct ib_device *device, void *client_data)
 {
-	struct ib_ucm_device *ucm_dev = ib_get_client_data(device, &ucm_client);
+	struct ib_ucm_device *ucm_dev = client_data;
 
 	if (!ucm_dev)
 		return;
diff --git a/drivers/infiniband/core/user_mad.c b/drivers/infiniband/core/user_mad.c
index 35567fffaa4e..57f281f8d686 100644
--- a/drivers/infiniband/core/user_mad.c
+++ b/drivers/infiniband/core/user_mad.c
@@ -133,7 +133,7 @@ static DEFINE_SPINLOCK(port_lock);
 static DECLARE_BITMAP(dev_map, IB_UMAD_MAX_PORTS);
 
 static void ib_umad_add_one(struct ib_device *device);
-static void ib_umad_remove_one(struct ib_device *device);
+static void ib_umad_remove_one(struct ib_device *device, void *client_data);
 
 static void ib_umad_release_dev(struct kobject *kobj)
 {
@@ -1322,9 +1322,9 @@ free:
 	kobject_put(&umad_dev->kobj);
 }
 
-static void ib_umad_remove_one(struct ib_device *device)
+static void ib_umad_remove_one(struct ib_device *device, void *client_data)
 {
-	struct ib_umad_device *umad_dev = ib_get_client_data(device, &umad_client);
+	struct ib_umad_device *umad_dev = client_data;
 	int i;
 
 	if (!umad_dev)
diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c
index f6eef2da7097..46c92294afa5 100644
--- a/drivers/infiniband/core/uverbs_main.c
+++ b/drivers/infiniband/core/uverbs_main.c
@@ -128,7 +128,7 @@ static int (*uverbs_ex_cmd_table[])(struct ib_uverbs_file *file,
 };
 
 static void ib_uverbs_add_one(struct ib_device *device);
-static void ib_uverbs_remove_one(struct ib_device *device);
+static void ib_uverbs_remove_one(struct ib_device *device, void *client_data);
 
 static void ib_uverbs_release_dev(struct kref *ref)
 {
@@ -948,9 +948,9 @@ err:
 	return;
 }
 
-static void ib_uverbs_remove_one(struct ib_device *device)
+static void ib_uverbs_remove_one(struct ib_device *device, void *client_data)
 {
-	struct ib_uverbs_device *uverbs_dev = ib_get_client_data(device, &uverbs_client);
+	struct ib_uverbs_device *uverbs_dev = client_data;
 
 	if (!uverbs_dev)
 		return;