From: Konrad Lipinski <konrad.l@samsung.com>
Date: Wed, 16 Nov 2016 18:52:03 +0000 (+0100)
Subject: kdbus: conn_call() cleanup
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=0c8769a7632c1a618345372955b5073f863f39dd;p=platform%2Fkernel%2Flinux-exynos.git

kdbus: conn_call() cleanup
---

diff --git a/ipc/kdbus/connection.c b/ipc/kdbus/connection.c
index e0508d82d551..74373ddf8345 100644
--- a/ipc/kdbus/connection.c
+++ b/ipc/kdbus/connection.c
@@ -1070,8 +1070,7 @@ static int kdbus_conn_call(struct kdbus_conn *src,
 	struct kdbus_conn *dst;
 	struct kdbus_bus *bus;
 	int ret;
-	bool has_sync_reply;
-	bool free_wait;
+	typeof(wait->waiting) waiting;
 	kdbus_assert(staging);
 	kdbus_assert(*staging);
 	kdbus_assert(src);
@@ -1090,8 +1089,6 @@ static int kdbus_conn_call(struct kdbus_conn *src,
 
 restart:
 	wait = NULL;
-	has_sync_reply = false;
-	free_wait = false;
 
 	/* name-registry must be locked for lookup *and* collecting data */
 	down_read(&bus->name_registry.rwlock);
@@ -1158,6 +1155,7 @@ read_unlock:
 		 */
 		if (!kdbus_conn_active(src)) {
 			ret = -ECONNRESET;
+			waiting = 1;
 			break;
 		}
 
@@ -1165,10 +1163,8 @@ read_unlock:
 		 * After the replying peer unset the waiting variable
 		 * it will wake us up.
 		 */
-		if (wait->waiting <= 0) {
-			has_sync_reply = true;
+		if ((waiting = wait->waiting) <= 0) /* reply present (receive) or sync moved (reissue call) */
 			break;
-		}
 
 		if (cancel_fd && POLLIN & cancel_fd->f_op->poll(cancel_fd, &pwq.pt)) {
 			ret = -ECANCELED;
@@ -1196,46 +1192,40 @@ read_unlock:
 	poll_freewait(&pwq);
 
 	/* reap */
-	if (!has_sync_reply) {
+	if (waiting > 0) { /* no reply yet - recheck under lock */
+		bool free_wait = true;
 		mutex_lock(&dst->lock);
-		if (wait->waiting <= 0) { /* reply is now present */
-			kdbus_assert(wait->queue_entry.reply_state < 0); /* wait is now completely divorced from dst */
-			has_sync_reply = true;
-		} else { /* reply is not present yet - abort the call */
+		if (0 < (waiting = wait->waiting)) { /* reply is not present yet - abort the call */
 			var(reply_state, wait->queue_entry.reply_state);
 			if (reply_state >= 0) { /* still linked - unlink and free the message so that replier will never see it */
 				if (reply_state > 0) /* still enqueued in dst */
 					kdbus_queue_entry_destroy(&wait->queue_entry, dst);
 				else /* only dequeued sync replies are actually linked */
 					kdbus_reply_unlink(wait);
-				free_wait = true;
-			} else /* unlinked but still in the process of answering */
+			} else { /* unlinked but in the process of being answered */
 				wait->waiting = 0; /* pity, inform replier we don't care anymore */
-		}
+				free_wait = false;
+			}
+		} else if (!waiting) /* reply present */
+			kdbus_assert(wait->queue_entry.reply_state < 0); /* wait is now completely divorced from dst */
 		mutex_unlock(&dst->lock);
+		if (unlikely(!free_wait)) /* will be freed by replier who has already been informed */
+			goto end;
 	}
 
-	if (has_sync_reply) {
-		if (unlikely(wait->waiting < 0)) { /* the object got moved - need to reissue the entire call */
-			kdbus_reply_free(wait);
-			goto restart;
-		}
-		ret = wait->err;
-		free_wait = true;
-	}
-
-	if (!ret) { /* we got an actual reply: let's install */
+	if (!waiting && !(ret = wait->err)) { /* we got an actual reply: let's install */
 		struct kdbus_queue_entry *entry = &wait->queue_entry;
 		mutex_lock(&src->lock);
-		ret = kdbus_queue_entry_install(entry, src, &cmd_send->reply.return_flags, true);
-		kdbus_pool_slice_publish(&src->pool, entry->slice, &cmd_send->reply.offset, &cmd_send->reply.msg_size);
+		if (!(ret = kdbus_queue_entry_install(entry, src, &cmd_send->reply.return_flags, true)))
+			kdbus_pool_slice_publish(&src->pool, entry->slice, &cmd_send->reply.offset, &cmd_send->reply.msg_size);
 		kdbus_queue_entry_destroy_nounlink(entry, src);
 		mutex_unlock(&src->lock);
 	}
 
-	if (free_wait)
-		kdbus_reply_free(wait);
-
+	kdbus_reply_free(wait);
+	if (unlikely(waiting < 0)) /* the object got moved - need to reissue the entire call */
+		goto restart;
+end:
 	return -EINTR == ret ? -ERESTARTSYS : ret;
 }
 
diff --git a/ipc/kdbus/reply.h b/ipc/kdbus/reply.h
index cf16f6337fd6..f05d27e55385 100644
--- a/ipc/kdbus/reply.h
+++ b/ipc/kdbus/reply.h
@@ -40,7 +40,7 @@ struct kdbus_reply {
 	u64 cookie;
 	union {
 		u64 deadline_ns; /* async */
-		int waiting; /* sync; 1 == sync caller waiting, 0 == sync caller gone or reply present, -1 == sync moved (need to reissue call t) */
+		int waiting; /* sync; 1 == sync caller waiting, 0 == sync caller gone or reply present, -1 == sync moved (need to reissue call) */
 	};
 	struct kdbus_conn *reply_dst;
 	int err;