1 files changed, 131 insertions, 49 deletions

diff --git a/arch/powerpc/platforms/powernv/opal-async.c b/arch/powerpc/platforms/powernv/opal-async.c
index cf33769..18a355f 100644
--- a/arch/powerpc/platforms/powernv/opal-async.c
+++ b/arch/powerpc/platforms/powernv/opal-async.c
@@ -1,7 +1,7 @@
 /*
  * PowerNV OPAL asynchronous completion interfaces
  *
- * Copyright 2013 IBM Corp.
+ * Copyright 2013-2017 IBM Corp.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -23,40 +23,50 @@
 #include <asm/machdep.h>
 #include <asm/opal.h>
 
-#define N_ASYNC_COMPLETIONS	64
+enum opal_async_token_state {
+	ASYNC_TOKEN_UNALLOCATED = 0,
+	ASYNC_TOKEN_ALLOCATED,
+	ASYNC_TOKEN_DISPATCHED,
+	ASYNC_TOKEN_ABANDONED,
+	ASYNC_TOKEN_COMPLETED
+};
+
+struct opal_async_token {
+	enum opal_async_token_state state;
+	struct opal_msg response;
+};
 
-static DECLARE_BITMAP(opal_async_complete_map, N_ASYNC_COMPLETIONS) = {~0UL};
-static DECLARE_BITMAP(opal_async_token_map, N_ASYNC_COMPLETIONS);
 static DECLARE_WAIT_QUEUE_HEAD(opal_async_wait);
 static DEFINE_SPINLOCK(opal_async_comp_lock);
 static struct semaphore opal_async_sem;
-static struct opal_msg *opal_async_responses;
 static unsigned int opal_max_async_tokens;
+static struct opal_async_token *opal_async_tokens;
 
-int __opal_async_get_token(void)
+static int __opal_async_get_token(void)
 {
 	unsigned long flags;
-	int token;
+	int i, token = -EBUSY;
 
 	spin_lock_irqsave(&opal_async_comp_lock, flags);
-	token = find_first_bit(opal_async_complete_map, opal_max_async_tokens);
-	if (token >= opal_max_async_tokens) {
-		token = -EBUSY;
-		goto out;
-	}
 
-	if (__test_and_set_bit(token, opal_async_token_map)) {
-		token = -EBUSY;
-		goto out;
+	for (i = 0; i < opal_max_async_tokens; i++) {
+		if (opal_async_tokens[i].state == ASYNC_TOKEN_UNALLOCATED) {
+			opal_async_tokens[i].state = ASYNC_TOKEN_ALLOCATED;
+			token = i;
+			break;
+		}
 	}
 
-	__clear_bit(token, opal_async_complete_map);
-
-out:
 	spin_unlock_irqrestore(&opal_async_comp_lock, flags);
 	return token;
 }
 
+/*
+ * Note: If the returned token is used in an opal call and opal returns
+ * OPAL_ASYNC_COMPLETION you MUST call one of opal_async_wait_response() or
+ * opal_async_wait_response_interruptible() at least once before calling another
+ * opal_async_* function
+ */
 int opal_async_get_token_interruptible(void)
 {
 	int token;
@@ -73,9 +83,10 @@ int opal_async_get_token_interruptible(void)
 }
 EXPORT_SYMBOL_GPL(opal_async_get_token_interruptible);
 
-int __opal_async_release_token(int token)
+static int __opal_async_release_token(int token)
 {
 	unsigned long flags;
+	int rc;
 
 	if (token < 0 || token >= opal_max_async_tokens) {
 		pr_err("%s: Passed token is out of range, token %d\n",
@@ -84,11 +95,26 @@ int __opal_async_release_token(int token)
 	}
 
 	spin_lock_irqsave(&opal_async_comp_lock, flags);
-	__set_bit(token, opal_async_complete_map);
-	__clear_bit(token, opal_async_token_map);
+	switch (opal_async_tokens[token].state) {
+	case ASYNC_TOKEN_COMPLETED:
+	case ASYNC_TOKEN_ALLOCATED:
+		opal_async_tokens[token].state = ASYNC_TOKEN_UNALLOCATED;
+		rc = 0;
+		break;
+	/*
+	 * DISPATCHED and ABANDONED tokens must wait for OPAL to respond.
+	 * Mark a DISPATCHED token as ABANDONED so that the response handling
+	 * code knows no one cares and that it can free it then.
+	 */
+	case ASYNC_TOKEN_DISPATCHED:
+		opal_async_tokens[token].state = ASYNC_TOKEN_ABANDONED;
+		/* Fall through */
+	default:
+		rc = 1;
+	}
 	spin_unlock_irqrestore(&opal_async_comp_lock, flags);
 
-	return 0;
+	return rc;
 }
 
 int opal_async_release_token(int token)
@@ -96,12 +122,10 @@ int opal_async_release_token(int token)
 	int ret;
 
 	ret = __opal_async_release_token(token);
-	if (ret)
-		return ret;
-
-	up(&opal_async_sem);
+	if (!ret)
+		up(&opal_async_sem);
 
-	return 0;
+	return ret;
 }
 EXPORT_SYMBOL_GPL(opal_async_release_token);
 
@@ -117,22 +141,83 @@ int opal_async_wait_response(uint64_t token, struct opal_msg *msg)
 		return -EINVAL;
 	}
 
-	/* Wakeup the poller before we wait for events to speed things
+	/*
+	 * There is no need to mark the token as dispatched, wait_event()
+	 * will block until the token completes.
+	 *
+	 * Wakeup the poller before we wait for events to speed things
 	 * up on platforms or simulators where the interrupts aren't
 	 * functional.
 	 */
 	opal_wake_poller();
-	wait_event(opal_async_wait, test_bit(token, opal_async_complete_map));
-	memcpy(msg, &opal_async_responses[token], sizeof(*msg));
+	wait_event(opal_async_wait, opal_async_tokens[token].state
+			== ASYNC_TOKEN_COMPLETED);
+	memcpy(msg, &opal_async_tokens[token].response, sizeof(*msg));
 
 	return 0;
 }
 EXPORT_SYMBOL_GPL(opal_async_wait_response);
 
+int opal_async_wait_response_interruptible(uint64_t token, struct opal_msg *msg)
+{
+	unsigned long flags;
+	int ret;
+
+	if (token >= opal_max_async_tokens) {
+		pr_err("%s: Invalid token passed\n", __func__);
+		return -EINVAL;
+	}
+
+	if (!msg) {
+		pr_err("%s: Invalid message pointer passed\n", __func__);
+		return -EINVAL;
+	}
+
+	/*
+	 * The first time this gets called we mark the token as DISPATCHED
+	 * so that if wait_event_interruptible() returns not zero and the
+	 * caller frees the token, we know not to actually free the token
+	 * until the response comes.
+	 *
+	 * Only change if the token is ALLOCATED - it may have been
+	 * completed even before the caller gets around to calling this
+	 * the first time.
+	 *
+	 * There is also a dirty great comment at the token allocation
+	 * function that if the opal call returns OPAL_ASYNC_COMPLETION to
+	 * the caller then the caller *must* call this or the not
+	 * interruptible version before doing anything else with the
+	 * token.
+	 */
+	if (opal_async_tokens[token].state == ASYNC_TOKEN_ALLOCATED) {
+		spin_lock_irqsave(&opal_async_comp_lock, flags);
+		if (opal_async_tokens[token].state == ASYNC_TOKEN_ALLOCATED)
+			opal_async_tokens[token].state = ASYNC_TOKEN_DISPATCHED;
+		spin_unlock_irqrestore(&opal_async_comp_lock, flags);
+	}
+
+	/*
+	 * Wakeup the poller before we wait for events to speed things
+	 * up on platforms or simulators where the interrupts aren't
+	 * functional.
+	 */
+	opal_wake_poller();
+	ret = wait_event_interruptible(opal_async_wait,
+			opal_async_tokens[token].state ==
+			ASYNC_TOKEN_COMPLETED);
+	if (!ret)
+		memcpy(msg, &opal_async_tokens[token].response, sizeof(*msg));
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(opal_async_wait_response_interruptible);
+
+/* Called from interrupt context */
 static int opal_async_comp_event(struct notifier_block *nb,
 		unsigned long msg_type, void *msg)
 {
 	struct opal_msg *comp_msg = msg;
+	enum opal_async_token_state state;
 	unsigned long flags;
 	uint64_t token;
 
@@ -140,11 +225,17 @@ static int opal_async_comp_event(struct notifier_block *nb,
 		return 0;
 
 	token = be64_to_cpu(comp_msg->params[0]);
-	memcpy(&opal_async_responses[token], comp_msg, sizeof(*comp_msg));
 	spin_lock_irqsave(&opal_async_comp_lock, flags);
-	__set_bit(token, opal_async_complete_map);
+	state = opal_async_tokens[token].state;
+	opal_async_tokens[token].state = ASYNC_TOKEN_COMPLETED;
 	spin_unlock_irqrestore(&opal_async_comp_lock, flags);
 
+	if (state == ASYNC_TOKEN_ABANDONED) {
+		/* Free the token, no one else will */
+		opal_async_release_token(token);
+		return 0;
+	}
+	memcpy(&opal_async_tokens[token].response, comp_msg, sizeof(*comp_msg));
 	wake_up(&opal_async_wait);
 
 	return 0;
@@ -178,32 +269,23 @@ int __init opal_async_comp_init(void)
 	}
 
 	opal_max_async_tokens = be32_to_cpup(async);
-	if (opal_max_async_tokens > N_ASYNC_COMPLETIONS)
-		opal_max_async_tokens = N_ASYNC_COMPLETIONS;
+	opal_async_tokens = kcalloc(opal_max_async_tokens,
+			sizeof(*opal_async_tokens), GFP_KERNEL);
+	if (!opal_async_tokens) {
+		err = -ENOMEM;
+		goto out_opal_node;
+	}
 
 	err = opal_message_notifier_register(OPAL_MSG_ASYNC_COMP,
 			&opal_async_comp_nb);
 	if (err) {
 		pr_err("%s: Can't register OPAL event notifier (%d)\n",
 				__func__, err);
+		kfree(opal_async_tokens);
 		goto out_opal_node;
 	}
 
-	opal_async_responses = kzalloc(
-			sizeof(*opal_async_responses) * opal_max_async_tokens,
-			GFP_KERNEL);
-	if (!opal_async_responses) {
-		pr_err("%s: Out of memory, failed to do asynchronous "
-				"completion init\n", __func__);
-		err = -ENOMEM;
-		goto out_opal_node;
-	}
-
-	/* Initialize to 1 less than the maximum tokens available, as we may
-	 * require to pop one during emergency through synchronous call to
-	 * __opal_async_get_token()
-	 */
-	sema_init(&opal_async_sem, opal_max_async_tokens - 1);
+	sema_init(&opal_async_sem, opal_max_async_tokens);
 
 out_opal_node:
 	of_node_put(opal_node);