Merge tag 'for-linus-6.16-1' of https://github.com/cminyard/linux-ipmi

Pull IPMI updates from Corey Minyard:
 "Restructure the IPMI driver.

  This is a restructure of the IPMI driver, mostly to remove SRCU. The
  locking had issues, and they were not going to be straightforward to
  fix. Plus it used tons of memory and was generally a pain.

  Most of this moves handling of messages out of bh and interrupt
  context and runs it in thread context. Then getting rid of SRCU is
  easy.

  This also has a minor cleanup to remove a warning on newer GCCs and to
  fix some documentation"

* tag 'for-linus-6.16-1' of https://github.com/cminyard/linux-ipmi: (26 commits)
  docs: ipmi: fix spelling and grammar mistakes
  ipmi:msghandler: Fix potential memory corruption in ipmi_create_user()
  ipmi:watchdog: Use the new interface for panic messages
  ipmi:msghandler: Export and fix panic messaging capability
  Documentation:ipmi: Remove comments about interrupt level
  ipmi:ssif: Fix a shutdown race
  ipmi:msghandler: Don't deliver messages to deleted users
  ipmi:si: Rework startup of IPMI devices
  ipmi:msghandler: Add a error return from unhandle LAN cmds
  ipmi:msghandler: Shut down lower layer first at unregister
  ipmi:msghandler: Remove proc_fs.h
  ipmi:msghandler: Don't check for shutdown when returning responses
  ipmi:msghandler: Don't acquire a user refcount for queued messages
  ipmi:msghandler: Fix locking around users and interfaces
  ipmi:msghandler: Remove some user level processing in panic mode
  ipmi: Add a note about the pretimeout callback
  ipmi:watchdog: Change lock to mutex
  ipmi:msghandler: Remove srcu for the ipmi_interfaces list
  ipmi:msghandler: Remove srcu from the ipmi user structure
  ipmi:msghandler: Use the system_wq, not system_bh_wq
  ...

8 files changed, 559 insertions, 507 deletions

diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
index 3ba9d7e9a6c7..064944ae9fdc 100644
--- a/drivers/char/ipmi/ipmi_msghandler.c
+++ b/drivers/char/ipmi/ipmi_msghandler.c
@@ -27,7 +27,6 @@
 #include <linux/ipmi_smi.h>
 #include <linux/notifier.h>
 #include <linux/init.h>
-#include <linux/proc_fs.h>
 #include <linux/rcupdate.h>
 #include <linux/interrupt.h>
 #include <linux/moduleparam.h>
@@ -41,11 +40,12 @@
 
 static struct ipmi_recv_msg *ipmi_alloc_recv_msg(void);
 static int ipmi_init_msghandler(void);
-static void smi_recv_work(struct work_struct *t);
+static void smi_work(struct work_struct *t);
 static void handle_new_recv_msgs(struct ipmi_smi *intf);
 static void need_waiter(struct ipmi_smi *intf);
 static int handle_one_recv_msg(struct ipmi_smi *intf,
 			       struct ipmi_smi_msg *msg);
+static void intf_free(struct kref *ref);
 
 static bool initialized;
 static bool drvregistered;
@@ -180,14 +180,8 @@ MODULE_PARM_DESC(max_msgs_per_user,
 struct ipmi_user {
 	struct list_head link;
 
-	/*
-	 * Set to NULL when the user is destroyed, a pointer to myself
-	 * so srcu_dereference can be used on it.
-	 */
-	struct ipmi_user *self;
-	struct srcu_struct release_barrier;
-
 	struct kref refcount;
+	refcount_t destroyed;
 
 	/* The upper layer that handles receive messages. */
 	const struct ipmi_user_hndl *handler;
@@ -200,30 +194,8 @@ struct ipmi_user {
 	bool gets_events;
 
 	atomic_t nr_msgs;
-
-	/* Free must run in process context for RCU cleanup. */
-	struct work_struct remove_work;
 };
 
-static struct workqueue_struct *remove_work_wq;
-
-static struct ipmi_user *acquire_ipmi_user(struct ipmi_user *user, int *index)
-	__acquires(user->release_barrier)
-{
-	struct ipmi_user *ruser;
-
-	*index = srcu_read_lock(&user->release_barrier);
-	ruser = srcu_dereference(user->self, &user->release_barrier);
-	if (!ruser)
-		srcu_read_unlock(&user->release_barrier, *index);
-	return ruser;
-}
-
-static void release_ipmi_user(struct ipmi_user *user, int index)
-{
-	srcu_read_unlock(&user->release_barrier, index);
-}
-
 struct cmd_rcvr {
 	struct list_head link;
 
@@ -327,6 +299,8 @@ struct bmc_device {
 };
 #define to_bmc_device(x) container_of((x), struct bmc_device, pdev.dev)
 
+static struct workqueue_struct *bmc_remove_work_wq;
+
 static int bmc_get_device_id(struct ipmi_smi *intf, struct bmc_device *bmc,
 			     struct ipmi_device_id *id,
 			     bool *guid_set, guid_t *guid);
@@ -451,11 +425,10 @@ struct ipmi_smi {
 	struct list_head link;
 
 	/*
-	 * The list of upper layers that are using me.  seq_lock write
-	 * protects this.  Read protection is with srcu.
+	 * The list of upper layers that are using me.
 	 */
 	struct list_head users;
-	struct srcu_struct users_srcu;
+	struct mutex users_mutex;
 	atomic_t nr_users;
 	struct device_attribute nr_users_devattr;
 	struct device_attribute nr_msgs_devattr;
@@ -496,15 +469,22 @@ struct ipmi_smi {
 	int curr_seq;
 
 	/*
-	 * Messages queued for delivery.  If delivery fails (out of memory
-	 * for instance), They will stay in here to be processed later in a
-	 * periodic timer interrupt.  The workqueue is for handling received
-	 * messages directly from the handler.
+	 * Messages queued for deliver to the user.
+	 */
+	struct mutex user_msgs_mutex;
+	struct list_head user_msgs;
+
+	/*
+	 * Messages queued for processing.  If processing fails (out
+	 * of memory for instance), They will stay in here to be
+	 * processed later in a periodic timer interrupt.  The
+	 * workqueue is for handling received messages directly from
+	 * the handler.
 	 */
 	spinlock_t       waiting_rcv_msgs_lock;
 	struct list_head waiting_rcv_msgs;
 	atomic_t	 watchdog_pretimeouts_to_deliver;
-	struct work_struct recv_work;
+	struct work_struct smi_work;
 
 	spinlock_t             xmit_msgs_lock;
 	struct list_head       xmit_msgs;
@@ -522,10 +502,9 @@ struct ipmi_smi {
 	 * Events that were queues because no one was there to receive
 	 * them.
 	 */
-	spinlock_t       events_lock; /* For dealing with event stuff. */
+	struct mutex     events_mutex; /* For dealing with event stuff. */
 	struct list_head waiting_events;
 	unsigned int     waiting_events_count; /* How many events in queue? */
-	char             delivering_events;
 	char             event_msg_printed;
 
 	/* How many users are waiting for events? */
@@ -613,6 +592,28 @@ static int __ipmi_bmc_register(struct ipmi_smi *intf,
 			       bool guid_set, guid_t *guid, int intf_num);
 static int __scan_channels(struct ipmi_smi *intf, struct ipmi_device_id *id);
 
+static void free_ipmi_user(struct kref *ref)
+{
+	struct ipmi_user *user = container_of(ref, struct ipmi_user, refcount);
+	struct module *owner;
+
+	owner = user->intf->owner;
+	kref_put(&user->intf->refcount, intf_free);
+	module_put(owner);
+	vfree(user);
+}
+
+static void release_ipmi_user(struct ipmi_user *user)
+{
+	kref_put(&user->refcount, free_ipmi_user);
+}
+
+static struct ipmi_user *acquire_ipmi_user(struct ipmi_user *user)
+{
+	if (!kref_get_unless_zero(&user->refcount))
+		return NULL;
+	return user;
+}
 
 /*
  * The driver model view of the IPMI messaging driver.
@@ -630,9 +631,6 @@ static DEFINE_MUTEX(ipmidriver_mutex);
 
 static LIST_HEAD(ipmi_interfaces);
 static DEFINE_MUTEX(ipmi_interfaces_mutex);
-#define ipmi_interfaces_mutex_held() \
-	lockdep_is_held(&ipmi_interfaces_mutex)
-static struct srcu_struct ipmi_interfaces_srcu;
 
 /*
  * List of watchers that want to know when smi's are added and deleted.
@@ -698,27 +696,20 @@ static void free_smi_msg_list(struct list_head *q)
 	}
 }
 
-static void clean_up_interface_data(struct ipmi_smi *intf)
+static void intf_free(struct kref *ref)
 {
+	struct ipmi_smi *intf = container_of(ref, struct ipmi_smi, refcount);
 	int              i;
 	struct cmd_rcvr  *rcvr, *rcvr2;
-	struct list_head list;
-
-	cancel_work_sync(&intf->recv_work);
 
 	free_smi_msg_list(&intf->waiting_rcv_msgs);
 	free_recv_msg_list(&intf->waiting_events);
 
 	/*
 	 * Wholesale remove all the entries from the list in the
-	 * interface and wait for RCU to know that none are in use.
+	 * interface.  No need for locks, this is single-threaded.
 	 */
-	mutex_lock(&intf->cmd_rcvrs_mutex);
-	INIT_LIST_HEAD(&list);
-	list_splice_init_rcu(&intf->cmd_rcvrs, &list, synchronize_rcu);
-	mutex_unlock(&intf->cmd_rcvrs_mutex);
-
-	list_for_each_entry_safe(rcvr, rcvr2, &list, link)
+	list_for_each_entry_safe(rcvr, rcvr2, &intf->cmd_rcvrs, link)
 		kfree(rcvr);
 
 	for (i = 0; i < IPMI_IPMB_NUM_SEQ; i++) {
@@ -726,20 +717,17 @@ static void clean_up_interface_data(struct ipmi_smi *intf)
 					&& (intf->seq_table[i].recv_msg))
 			ipmi_free_recv_msg(intf->seq_table[i].recv_msg);
 	}
-}
-
-static void intf_free(struct kref *ref)
-{
-	struct ipmi_smi *intf = container_of(ref, struct ipmi_smi, refcount);
 
-	clean_up_interface_data(intf);
 	kfree(intf);
 }
 
 int ipmi_smi_watcher_register(struct ipmi_smi_watcher *watcher)
 {
 	struct ipmi_smi *intf;
-	int index, rv;
+	unsigned int count = 0, i;
+	int *interfaces = NULL;
+	struct device **devices = NULL;
+	int rv = 0;
 
 	/*
 	 * Make sure the driver is actually initialized, this handles
@@ -753,20 +741,53 @@ int ipmi_smi_watcher_register(struct ipmi_smi_watcher *watcher)
 
 	list_add(&watcher->link, &smi_watchers);
 
-	index = srcu_read_lock(&ipmi_interfaces_srcu);
-	list_for_each_entry_rcu(intf, &ipmi_interfaces, link,
-			lockdep_is_held(&smi_watchers_mutex)) {
-		int intf_num = READ_ONCE(intf->intf_num);
+	/*
+	 * Build an array of ipmi interfaces and fill it in, and
+	 * another array of the devices.  We can't call the callback
+	 * with ipmi_interfaces_mutex held.  smi_watchers_mutex will
+	 * keep things in order for the user.
+	 */
+	mutex_lock(&ipmi_interfaces_mutex);
+	list_for_each_entry(intf, &ipmi_interfaces, link)
+		count++;
+	if (count > 0) {
+		interfaces = kmalloc_array(count, sizeof(*interfaces),
+					   GFP_KERNEL);
+		if (!interfaces) {
+			rv = -ENOMEM;
+		} else {
+			devices = kmalloc_array(count, sizeof(*devices),
+						GFP_KERNEL);
+			if (!devices) {
+				kfree(interfaces);
+				interfaces = NULL;
+				rv = -ENOMEM;
+			}
+		}
+		count = 0;
+	}
+	if (interfaces) {
+		list_for_each_entry(intf, &ipmi_interfaces, link) {
+			int intf_num = READ_ONCE(intf->intf_num);
 
-		if (intf_num == -1)
-			continue;
-		watcher->new_smi(intf_num, intf->si_dev);
+			if (intf_num == -1)
+				continue;
+			devices[count] = intf->si_dev;
+			interfaces[count++] = intf_num;
+		}
+	}
+	mutex_unlock(&ipmi_interfaces_mutex);
+
+	if (interfaces) {
+		for (i = 0; i < count; i++)
+			watcher->new_smi(interfaces[i], devices[i]);
+		kfree(interfaces);
+		kfree(devices);
 	}
-	srcu_read_unlock(&ipmi_interfaces_srcu, index);
 
 	mutex_unlock(&smi_watchers_mutex);
 
-	return 0;
+	return rv;
 }
 EXPORT_SYMBOL(ipmi_smi_watcher_register);
 
@@ -779,22 +800,17 @@ int ipmi_smi_watcher_unregister(struct ipmi_smi_watcher *watcher)
 }
 EXPORT_SYMBOL(ipmi_smi_watcher_unregister);
 
-/*
- * Must be called with smi_watchers_mutex held.
- */
 static void
 call_smi_watchers(int i, struct device *dev)
 {
 	struct ipmi_smi_watcher *w;
 
-	mutex_lock(&smi_watchers_mutex);
 	list_for_each_entry(w, &smi_watchers, link) {
 		if (try_module_get(w->owner)) {
 			w->new_smi(i, dev);
 			module_put(w->owner);
 		}
 	}
-	mutex_unlock(&smi_watchers_mutex);
 }
 
 static int
@@ -941,18 +957,14 @@ static int deliver_response(struct ipmi_smi *intf, struct ipmi_recv_msg *msg)
 		ipmi_free_recv_msg(msg);
 		atomic_dec(&msg->user->nr_msgs);
 	} else {
-		int index;
-		struct ipmi_user *user = acquire_ipmi_user(msg->user, &index);
-
-		if (user) {
-			atomic_dec(&user->nr_msgs);
-			user->handler->ipmi_recv_hndl(msg, user->handler_data);
-			release_ipmi_user(user, index);
-		} else {
-			/* User went away, give up. */
-			ipmi_free_recv_msg(msg);
-			rv = -EINVAL;
-		}
+		/*
+		 * Deliver it in smi_work.  The message will hold a
+		 * refcount to the user.
+		 */
+		mutex_lock(&intf->user_msgs_mutex);
+		list_add_tail(&msg->link, &intf->user_msgs);
+		mutex_unlock(&intf->user_msgs_mutex);
+		queue_work(system_wq, &intf->smi_work);
 	}
 
 	return rv;
@@ -1192,23 +1204,14 @@ static int intf_err_seq(struct ipmi_smi *intf,
 	return rv;
 }
 
-static void free_user_work(struct work_struct *work)
-{
-	struct ipmi_user *user = container_of(work, struct ipmi_user,
-					      remove_work);
-
-	cleanup_srcu_struct(&user->release_barrier);
-	vfree(user);
-}
-
 int ipmi_create_user(unsigned int          if_num,
 		     const struct ipmi_user_hndl *handler,
 		     void                  *handler_data,
 		     struct ipmi_user      **user)
 {
 	unsigned long flags;
-	struct ipmi_user *new_user;
-	int           rv, index;
+	struct ipmi_user *new_user = NULL;
+	int           rv = 0;
 	struct ipmi_smi *intf;
 
 	/*
@@ -1230,30 +1233,31 @@ int ipmi_create_user(unsigned int          if_num,
 	if (rv)
 		return rv;
 
-	new_user = vzalloc(sizeof(*new_user));
-	if (!new_user)
-		return -ENOMEM;
-
-	index = srcu_read_lock(&ipmi_interfaces_srcu);
-	list_for_each_entry_rcu(intf, &ipmi_interfaces, link) {
+	mutex_lock(&ipmi_interfaces_mutex);
+	list_for_each_entry(intf, &ipmi_interfaces, link) {
 		if (intf->intf_num == if_num)
 			goto found;
 	}
 	/* Not found, return an error */
 	rv = -EINVAL;
-	goto out_kfree;
+	goto out_unlock;
 
  found:
+	if (intf->in_shutdown) {
+		rv = -ENODEV;
+		goto out_unlock;
+	}
+
 	if (atomic_add_return(1, &intf->nr_users) > max_users) {
 		rv = -EBUSY;
 		goto out_kfree;
 	}
 
-	INIT_WORK(&new_user->remove_work, free_user_work);
-
-	rv = init_srcu_struct(&new_user->release_barrier);
-	if (rv)
+	new_user = vzalloc(sizeof(*new_user));
+	if (!new_user) {
+		rv = -ENOMEM;
 		goto out_kfree;
+	}
 
 	if (!try_module_get(intf->owner)) {
 		rv = -ENODEV;
@@ -1265,64 +1269,58 @@ int ipmi_create_user(unsigned int          if_num,
 
 	atomic_set(&new_user->nr_msgs, 0);
 	kref_init(&new_user->refcount);
+	refcount_set(&new_user->destroyed, 1);
+	kref_get(&new_user->refcount); /* Destroy owns a refcount. */
 	new_user->handler = handler;
 	new_user->handler_data = handler_data;
 	new_user->intf = intf;
 	new_user->gets_events = false;
 
-	rcu_assign_pointer(new_user->self, new_user);
+	mutex_lock(&intf->users_mutex);
 	spin_lock_irqsave(&intf->seq_lock, flags);
-	list_add_rcu(&new_user->link, &intf->users);
+	list_add(&new_user->link, &intf->users);
 	spin_unlock_irqrestore(&intf->seq_lock, flags);
+	mutex_unlock(&intf->users_mutex);
+
 	if (handler->ipmi_watchdog_pretimeout)
 		/* User wants pretimeouts, so make sure to watch for them. */
 		smi_add_watch(intf, IPMI_WATCH_MASK_CHECK_WATCHDOG);
-	srcu_read_unlock(&ipmi_interfaces_srcu, index);
-	*user = new_user;
-	return 0;
 
 out_kfree:
-	atomic_dec(&intf->nr_users);
-	srcu_read_unlock(&ipmi_interfaces_srcu, index);
-	vfree(new_user);
+	if (rv) {
+		atomic_dec(&intf->nr_users);
+		vfree(new_user);
+	} else {
+		*user = new_user;
+	}
+out_unlock:
+	mutex_unlock(&ipmi_interfaces_mutex);
 	return rv;
 }
 EXPORT_SYMBOL(ipmi_create_user);
 
 int ipmi_get_smi_info(int if_num, struct ipmi_smi_info *data)
 {
-	int rv, index;
+	int rv = -EINVAL;
 	struct ipmi_smi *intf;
 
-	index = srcu_read_lock(&ipmi_interfaces_srcu);
-	list_for_each_entry_rcu(intf, &ipmi_interfaces, link) {
-		if (intf->intf_num == if_num)
-			goto found;
+	mutex_lock(&ipmi_interfaces_mutex);
+	list_for_each_entry(intf, &ipmi_interfaces, link) {
+		if (intf->intf_num == if_num) {
+			if (!intf->handlers->get_smi_info)
+				rv = -ENOTTY;
+			else
+				rv = intf->handlers->get_smi_info(intf->send_info, data);
+			break;
+		}
 	}
-	srcu_read_unlock(&ipmi_interfaces_srcu, index);
-
-	/* Not found, return an error */
-	return -EINVAL;
-
-found:
-	if (!intf->handlers->get_smi_info)
-		rv = -ENOTTY;
-	else
-		rv = intf->handlers->get_smi_info(intf->send_info, data);
-	srcu_read_unlock(&ipmi_interfaces_srcu, index);
+	mutex_unlock(&ipmi_interfaces_mutex);
 
 	return rv;
 }
 EXPORT_SYMBOL(ipmi_get_smi_info);
 
-static void free_user(struct kref *ref)
-{
-	struct ipmi_user *user = container_of(ref, struct ipmi_user, refcount);
-
-	/* SRCU cleanup must happen in workqueue context. */
-	queue_work(remove_work_wq, &user->remove_work);
-}
-
+/* Must be called with intf->users_mutex held. */
 static void _ipmi_destroy_user(struct ipmi_user *user)
 {
 	struct ipmi_smi  *intf = user->intf;
@@ -1330,21 +1328,10 @@ static void _ipmi_destroy_user(struct ipmi_user *user)
 	unsigned long    flags;
 	struct cmd_rcvr  *rcvr;
 	struct cmd_rcvr  *rcvrs = NULL;
-	struct module    *owner;
+	struct ipmi_recv_msg *msg, *msg2;
 
-	if (!acquire_ipmi_user(user, &i)) {
-		/*
-		 * The user has already been cleaned up, just make sure
-		 * nothing is using it and return.
-		 */
-		synchronize_srcu(&user->release_barrier);
+	if (!refcount_dec_if_one(&user->destroyed))
 		return;
-	}
-
-	rcu_assign_pointer(user->self, NULL);
-	release_ipmi_user(user, i);
-
-	synchronize_srcu(&user->release_barrier);
 
 	if (user->handler->shutdown)
 		user->handler->shutdown(user->handler_data);
@@ -1355,11 +1342,11 @@ static void _ipmi_destroy_user(struct ipmi_user *user)
 	if (user->gets_events)
 		atomic_dec(&intf->event_waiters);
 
-	/* Remove the user from the interface's sequence table. */
-	spin_lock_irqsave(&intf->seq_lock, flags);
-	list_del_rcu(&user->link);
+	/* Remove the user from the interface's list and sequence table. */
+	list_del(&user->link);
 	atomic_dec(&intf->nr_users);
 
+	spin_lock_irqsave(&intf->seq_lock, flags);
 	for (i = 0; i < IPMI_IPMB_NUM_SEQ; i++) {
 		if (intf->seq_table[i].inuse
 		    && (intf->seq_table[i].recv_msg->user == user)) {
@@ -1374,7 +1361,7 @@ static void _ipmi_destroy_user(struct ipmi_user *user)
 	 * Remove the user from the command receiver's table.  First
 	 * we build a list of everything (not using the standard link,
 	 * since other things may be using it till we do
-	 * synchronize_srcu()) then free everything in that list.
+	 * synchronize_rcu()) then free everything in that list.
 	 */
 	mutex_lock(&intf->cmd_rcvrs_mutex);
 	list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link,
@@ -1386,23 +1373,33 @@ static void _ipmi_destroy_user(struct ipmi_user *user)
 		}
 	}
 	mutex_unlock(&intf->cmd_rcvrs_mutex);
-	synchronize_rcu();
 	while (rcvrs) {
 		rcvr = rcvrs;
 		rcvrs = rcvr->next;
 		kfree(rcvr);
 	}
 
-	owner = intf->owner;
-	kref_put(&intf->refcount, intf_free);
-	module_put(owner);
+	mutex_lock(&intf->user_msgs_mutex);
+	list_for_each_entry_safe(msg, msg2, &intf->user_msgs, link) {
+		if (msg->user != user)
+			continue;
+		list_del(&msg->link);
+		ipmi_free_recv_msg(msg);
+	}
+	mutex_unlock(&intf->user_msgs_mutex);
+
+	release_ipmi_user(user);
 }
 
 void ipmi_destroy_user(struct ipmi_user *user)
 {
+	struct ipmi_smi *intf = user->intf;
+
+	mutex_lock(&intf->users_mutex);
 	_ipmi_destroy_user(user);
+	mutex_unlock(&intf->users_mutex);
 
-	kref_put(&user->refcount, free_user);
+	kref_put(&user->refcount, free_ipmi_user);
 }
 EXPORT_SYMBOL(ipmi_destroy_user);
 
@@ -1411,9 +1408,9 @@ int ipmi_get_version(struct ipmi_user *user,
 		     unsigned char *minor)
 {
 	struct ipmi_device_id id;
-	int rv, index;
+	int rv;
 
-	user = acquire_ipmi_user(user, &index);
+	user = acquire_ipmi_user(user);
 	if (!user)
 		return -ENODEV;
 
@@ -1422,7 +1419,7 @@ int ipmi_get_version(struct ipmi_user *user,
 		*major = ipmi_version_major(&id);
 		*minor = ipmi_version_minor(&id);
 	}
-	release_ipmi_user(user, index);
+	release_ipmi_user(user);
 
 	return rv;
 }
@@ -1432,9 +1429,9 @@ int ipmi_set_my_address(struct ipmi_user *user,
 			unsigned int  channel,
 			unsigned char address)
 {
-	int index, rv = 0;
+	int rv = 0;
 
-	user = acquire_ipmi_user(user, &index);
+	user = acquire_ipmi_user(user);
 	if (!user)
 		return -ENODEV;
 
@@ -1444,7 +1441,7 @@ int ipmi_set_my_address(struct ipmi_user *user,
 		channel = array_index_nospec(channel, IPMI_MAX_CHANNELS);
 		user->intf->addrinfo[channel].address = address;
 	}
-	release_ipmi_user(user, index);
+	release_ipmi_user(user);
 
 	return rv;
 }
@@ -1454,9 +1451,9 @@ int ipmi_get_my_address(struct ipmi_user *user,
 			unsigned int  channel,
 			unsigned char *address)
 {
-	int index, rv = 0;
+	int rv = 0;
 
-	user = acquire_ipmi_user(user, &index);
+	user = acquire_ipmi_user(user);
 	if (!user)
 		return -ENODEV;
 
@@ -1466,7 +1463,7 @@ int ipmi_get_my_address(struct ipmi_user *user,
 		channel = array_index_nospec(channel, IPMI_MAX_CHANNELS);
 		*address = user->intf->addrinfo[channel].address;
 	}
-	release_ipmi_user(user, index);
+	release_ipmi_user(user);
 
 	return rv;
 }
@@ -1476,9 +1473,9 @@ int ipmi_set_my_LUN(struct ipmi_user *user,
 		    unsigned int  channel,
 		    unsigned char LUN)
 {
-	int index, rv = 0;
+	int rv = 0;
 
-	user = acquire_ipmi_user(user, &index);
+	user = acquire_ipmi_user(user);
 	if (!user)
 		return -ENODEV;
 
@@ -1488,7 +1485,7 @@ int ipmi_set_my_LUN(struct ipmi_user *user,
 		channel = array_index_nospec(channel, IPMI_MAX_CHANNELS);
 		user->intf->addrinfo[channel].lun = LUN & 0x3;
 	}
-	release_ipmi_user(user, index);
+	release_ipmi_user(user);
 
 	return rv;
 }
@@ -1498,9 +1495,9 @@ int ipmi_get_my_LUN(struct ipmi_user *user,
 		    unsigned int  channel,
 		    unsigned char *address)
 {
-	int index, rv = 0;
+	int rv = 0;
 
-	user = acquire_ipmi_user(user, &index);
+	user = acquire_ipmi_user(user);
 	if (!user)
 		return -ENODEV;
 
@@ -1510,7 +1507,7 @@ int ipmi_get_my_LUN(struct ipmi_user *user,
 		channel = array_index_nospec(channel, IPMI_MAX_CHANNELS);
 		*address = user->intf->addrinfo[channel].lun;
 	}
-	release_ipmi_user(user, index);
+	release_ipmi_user(user);
 
 	return rv;
 }
@@ -1518,17 +1515,17 @@ EXPORT_SYMBOL(ipmi_get_my_LUN);
 
 int ipmi_get_maintenance_mode(struct ipmi_user *user)
 {
-	int mode, index;
+	int mode;
 	unsigned long flags;
 
-	user = acquire_ipmi_user(user, &index);
+	user = acquire_ipmi_user(user);
 	if (!user)
 		return -ENODEV;
 
 	spin_lock_irqsave(&user->intf->maintenance_mode_lock, flags);
 	mode = user->intf->maintenance_mode;
 	spin_unlock_irqrestore(&user->intf->maintenance_mode_lock, flags);
-	release_ipmi_user(user, index);
+	release_ipmi_user(user);
 
 	return mode;
 }
@@ -1543,11 +1540,11 @@ static void maintenance_mode_update(struct ipmi_smi *intf)
 
 int ipmi_set_maintenance_mode(struct ipmi_user *user, int mode)
 {
-	int rv = 0, index;
+	int rv = 0;
 	unsigned long flags;
 	struct ipmi_smi *intf = user->intf;
 
-	user = acquire_ipmi_user(user, &index);
+	user = acquire_ipmi_user(user);
 	if (!user)
 		return -ENODEV;
 
@@ -1577,7 +1574,7 @@ int ipmi_set_maintenance_mode(struct ipmi_user *user, int mode)
 	}
  out_unlock:
 	spin_unlock_irqrestore(&intf->maintenance_mode_lock, flags);
-	release_ipmi_user(user, index);
+	release_ipmi_user(user);
 
 	return rv;
 }
@@ -1585,19 +1582,17 @@ EXPORT_SYMBOL(ipmi_set_maintenance_mode);
 
 int ipmi_set_gets_events(struct ipmi_user *user, bool val)
 {
-	unsigned long        flags;
 	struct ipmi_smi      *intf = user->intf;
 	struct ipmi_recv_msg *msg, *msg2;
 	struct list_head     msgs;
-	int index;
 
-	user = acquire_ipmi_user(user, &index);
+	user = acquire_ipmi_user(user);
 	if (!user)
 		return -ENODEV;
 
 	INIT_LIST_HEAD(&msgs);
 
-	spin_lock_irqsave(&intf->events_lock, flags);
+	mutex_lock(&intf->events_mutex);
 	if (user->gets_events == val)
 		goto out;
 
@@ -1610,13 +1605,6 @@ int ipmi_set_gets_events(struct ipmi_user *user, bool val)
 		atomic_dec(&intf->event_waiters);
 	}
 
-	if (intf->delivering_events)
-		/*
-		 * Another thread is delivering events for this, so
-		 * let it handle any new events.
-		 */
-		goto out;
-
 	/* Deliver any queued events. */
 	while (user->gets_events && !list_empty(&intf->waiting_events)) {
 		list_for_each_entry_safe(msg, msg2, &intf->waiting_events, link)
@@ -1627,22 +1615,16 @@ int ipmi_set_gets_events(struct ipmi_user *user, bool val)
 			intf->event_msg_printed = 0;
 		}
 
-		intf->delivering_events = 1;
-		spin_unlock_irqrestore(&intf->events_lock, flags);
-
 		list_for_each_entry_safe(msg, msg2, &msgs, link) {
 			msg->user = user;
 			kref_get(&user->refcount);
 			deliver_local_response(intf, msg);
 		}
-
-		spin_lock_irqsave(&intf->events_lock, flags);
-		intf->delivering_events = 0;
 	}
 
  out:
-	spin_unlock_irqrestore(&intf->events_lock, flags);
-	release_ipmi_user(user, index);
+	mutex_unlock(&intf->events_mutex);
+	release_ipmi_user(user);
 
 	return 0;
 }
@@ -1687,9 +1669,9 @@ int ipmi_register_for_cmd(struct ipmi_user *user,
 {
 	struct ipmi_smi *intf = user->intf;
 	struct cmd_rcvr *rcvr;
-	int rv = 0, index;
+	int rv = 0;
 
-	user = acquire_ipmi_user(user, &index);
+	user = acquire_ipmi_user(user);
 	if (!user)
 		return -ENODEV;
 
@@ -1719,7 +1701,7 @@ out_unlock:
 	if (rv)
 		kfree(rcvr);
 out_release:
-	release_ipmi_user(user, index);
+	release_ipmi_user(user);
 
 	return rv;
 }
@@ -1733,9 +1715,9 @@ int ipmi_unregister_for_cmd(struct ipmi_user *user,
 	struct ipmi_smi *intf = user->intf;
 	struct cmd_rcvr *rcvr;
 	struct cmd_rcvr *rcvrs = NULL;
-	int i, rv = -ENOENT, index;
+	int i, rv = -ENOENT;
 
-	user = acquire_ipmi_user(user, &index);
+	user = acquire_ipmi_user(user);
 	if (!user)
 		return -ENODEV;
 
@@ -1758,7 +1740,7 @@ int ipmi_unregister_for_cmd(struct ipmi_user *user,
 	}
 	mutex_unlock(&intf->cmd_rcvrs_mutex);
 	synchronize_rcu();
-	release_ipmi_user(user, index);
+	release_ipmi_user(user);
 	while (rcvrs) {
 		smi_remove_watch(intf, IPMI_WATCH_MASK_CHECK_COMMANDS);
 		rcvr = rcvrs;
@@ -1882,13 +1864,12 @@ static void smi_send(struct ipmi_smi *intf,
 		     const struct ipmi_smi_handlers *handlers,
 		     struct ipmi_smi_msg *smi_msg, int priority)
 {
-	int run_to_completion = intf->run_to_completion;
+	int run_to_completion = READ_ONCE(intf->run_to_completion);
 	unsigned long flags = 0;
 
 	if (!run_to_completion)
 		spin_lock_irqsave(&intf->xmit_msgs_lock, flags);
 	smi_msg = smi_add_send_msg(intf, smi_msg, priority);
-
 	if (!run_to_completion)
 		spin_unlock_irqrestore(&intf->xmit_msgs_lock, flags);
 
@@ -2304,6 +2285,7 @@ static int i_ipmi_request(struct ipmi_user     *user,
 {
 	struct ipmi_smi_msg *smi_msg;
 	struct ipmi_recv_msg *recv_msg;
+	int run_to_completion = READ_ONCE(intf->run_to_completion);
 	int rv = 0;
 
 	if (user) {
@@ -2337,7 +2319,8 @@ static int i_ipmi_request(struct ipmi_user     *user,
 		}
 	}
 
-	rcu_read_lock();
+	if (!run_to_completion)
+		mutex_lock(&intf->users_mutex);
 	if (intf->in_shutdown) {
 		rv = -ENODEV;
 		goto out_err;
@@ -2383,7 +2366,8 @@ out_err:
 
 		smi_send(intf, intf->handlers, smi_msg, priority);
 	}
-	rcu_read_unlock();
+	if (!run_to_completion)
+		mutex_unlock(&intf->users_mutex);
 
 out:
 	if (rv && user)
@@ -2414,12 +2398,12 @@ int ipmi_request_settime(struct ipmi_user *user,
 			 unsigned int     retry_time_ms)
 {
 	unsigned char saddr = 0, lun = 0;
-	int rv, index;
+	int rv;
 
 	if (!user)
 		return -EINVAL;
 
-	user = acquire_ipmi_user(user, &index);
+	user = acquire_ipmi_user(user);
 	if (!user)
 		return -ENODEV;
 
@@ -2438,7 +2422,7 @@ int ipmi_request_settime(struct ipmi_user *user,
 				    retries,
 				    retry_time_ms);
 
-	release_ipmi_user(user, index);
+	release_ipmi_user(user);
 	return rv;
 }
 EXPORT_SYMBOL(ipmi_request_settime);
@@ -2453,12 +2437,12 @@ int ipmi_request_supply_msgs(struct ipmi_user     *user,
 			     int                  priority)
 {
 	unsigned char saddr = 0, lun = 0;
-	int rv, index;
+	int rv;
 
 	if (!user)
 		return -EINVAL;
 
-	user = acquire_ipmi_user(user, &index);
+	user = acquire_ipmi_user(user);
 	if (!user)
 		return -ENODEV;
 
@@ -2477,7 +2461,7 @@ int ipmi_request_supply_msgs(struct ipmi_user     *user,
 				    lun,
 				    -1, 0);
 
-	release_ipmi_user(user, index);
+	release_ipmi_user(user);
 	return rv;
 }
 EXPORT_SYMBOL(ipmi_request_supply_msgs);
@@ -3064,7 +3048,7 @@ cleanup_bmc_device(struct kref *ref)
 	 * with removing the device attributes while reading a device
 	 * attribute.
 	 */
-	queue_work(remove_work_wq, &bmc->remove_work);
+	queue_work(bmc_remove_work_wq, &bmc->remove_work);
 }
 
 /*
@@ -3520,15 +3504,14 @@ static ssize_t nr_msgs_show(struct device *dev,
 			    char *buf)
 {
 	struct ipmi_smi *intf = container_of(attr,
-			 struct ipmi_smi, nr_msgs_devattr);
+					     struct ipmi_smi, nr_msgs_devattr);
 	struct ipmi_user *user;
-	int index;
 	unsigned int count = 0;
 
-	index = srcu_read_lock(&intf->users_srcu);
-	list_for_each_entry_rcu(user, &intf->users, link)
+	mutex_lock(&intf->users_mutex);
+	list_for_each_entry(user, &intf->users, link)
 		count += atomic_read(&user->nr_msgs);
-	srcu_read_unlock(&intf->users_srcu, index);
+	mutex_unlock(&intf->users_mutex);
 
 	return sysfs_emit(buf, "%u\n", count);
 }
@@ -3569,12 +3552,6 @@ int ipmi_add_smi(struct module         *owner,
 	if (!intf)
 		return -ENOMEM;
 
-	rv = init_srcu_struct(&intf->users_srcu);
-	if (rv) {
-		kfree(intf);
-		return rv;
-	}
-
 	intf->owner = owner;
 	intf->bmc = &intf->tmp_bmc;
 	INIT_LIST_HEAD(&intf->bmc->intfs);
@@ -3591,7 +3568,10 @@ int ipmi_add_smi(struct module         *owner,
 	}
 	if (slave_addr != 0)
 		intf->addrinfo[0].address = slave_addr;
+	INIT_LIST_HEAD(&intf->user_msgs);
+	mutex_init(&intf->user_msgs_mutex);
 	INIT_LIST_HEAD(&intf->users);
+	mutex_init(&intf->users_mutex);
 	atomic_set(&intf->nr_users, 0);
 	intf->handlers = handlers;
 	intf->send_info = send_info;
@@ -3603,12 +3583,12 @@ int ipmi_add_smi(struct module         *owner,
 	intf->curr_seq = 0;
 	spin_lock_init(&intf->waiting_rcv_msgs_lock);
 	INIT_LIST_HEAD(&intf->waiting_rcv_msgs);
-	INIT_WORK(&intf->recv_work, smi_recv_work);
+	INIT_WORK(&intf->smi_work, smi_work);
 	atomic_set(&intf->watchdog_pretimeouts_to_deliver, 0);
 	spin_lock_init(&intf->xmit_msgs_lock);
 	INIT_LIST_HEAD(&intf->xmit_msgs);
 	INIT_LIST_HEAD(&intf->hp_xmit_msgs);
-	spin_lock_init(&intf->events_lock);
+	mutex_init(&intf->events_mutex);
 	spin_lock_init(&intf->watch_lock);
 	atomic_set(&intf->event_waiters, 0);
 	intf->ticks_to_req_ev = IPMI_REQUEST_EV_TIME;
@@ -3621,12 +3601,16 @@ int ipmi_add_smi(struct module         *owner,
 	for (i = 0; i < IPMI_NUM_STATS; i++)