rapidio: run discovery as an asynchronous process

Modify mport initialization routine to run the RapidIO discovery process
asynchronously.  This allows to have an arbitrary order of enumerating and
discovering ports in systems with multiple RapidIO controllers without
creating a deadlock situation if enumerator port is registered after a
discovering one.

Making netID matching to mportID ensures consistent net ID assignment in
multiport RapidIO systems with asynchronous discovery process (global
counter implementation is affected by race between threads).

[akpm@linux-foundation.org: tweak code layput]
Signed-off-by: Alexandre Bounine <alexandre.bounine@idt.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Li Yang <leoli@freescale.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 49 insertions, 2 deletions

diff --git a/drivers/rapidio/rio.c b/drivers/rapidio/rio.c
index d7b68cc..d4bd690 100644
--- a/drivers/rapidio/rio.c
+++ b/drivers/rapidio/rio.c
@@ -1260,15 +1260,62 @@ static int __devinit rio_init(void)
 	return 0;
 }
 
+static struct workqueue_struct *rio_wq;
+
+struct rio_disc_work {
+	struct work_struct	work;
+	struct rio_mport	*mport;
+};
+
+static void __devinit disc_work_handler(struct work_struct *_work)
+{
+	struct rio_disc_work *work;
+
+	work = container_of(_work, struct rio_disc_work, work);
+	pr_debug("RIO: discovery work for mport %d %s\n",
+		 work->mport->id, work->mport->name);
+	rio_disc_mport(work->mport);
+
+	kfree(work);
+}
+
 int __devinit rio_init_mports(void)
 {
 	struct rio_mport *port;
+	struct rio_disc_work *work;
+	int no_disc = 0;
 
 	list_for_each_entry(port, &rio_mports, node) {
 		if (port->host_deviceid >= 0)
 			rio_enum_mport(port);
-		else
-			rio_disc_mport(port);
+		else if (!no_disc) {
+			if (!rio_wq) {
+				rio_wq = alloc_workqueue("riodisc", 0, 0);
+				if (!rio_wq) {
+					pr_err("RIO: unable allocate rio_wq\n");
+					no_disc = 1;
+					continue;
+				}
+			}
+
+			work = kzalloc(sizeof *work, GFP_KERNEL);
+			if (!work) {
+				pr_err("RIO: no memory for work struct\n");
+				no_disc = 1;
+				continue;
+			}
+
+			work->mport = port;
+			INIT_WORK(&work->work, disc_work_handler);
+			queue_work(rio_wq, &work->work);
+		}
+	}
+
+	if (rio_wq) {
+		pr_debug("RIO: flush discovery workqueue\n");
+		flush_workqueue(rio_wq);
+		pr_debug("RIO: flush discovery workqueue finished\n");
+		destroy_workqueue(rio_wq);
 	}
 
 	rio_init();