From 3e48acac26c8b5321ff5b752c8650e1cf4d04344 Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Wed, 2 Dec 2015 18:23:31 +0100 Subject: [PATCH] greybus: svc: fix racy hotplug handling Fix racy hotplug handling by serialising all processing of hot-plug and unplug requests using a single-threaded dedicated workqueue. This fixes a reported crash during enumeration when processing multiple events. The current svc implementation does not handle concurrency at all (e.g. no interface list lock or refcounting) so we need to use the big hammer for now. Note that we will eventually want to process events for different interfaces in parallel, but that we'd still need a workqueue in order not to starve other svc requests (e.g. for timesync). Reported-by: Vaibhav Hiremath Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman --- drivers/staging/greybus/svc.c | 12 ++++++++++-- drivers/staging/greybus/svc.h | 1 + 2 files changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/staging/greybus/svc.c b/drivers/staging/greybus/svc.c index 34713d6b0074..af41e8e49c31 100644 --- a/drivers/staging/greybus/svc.c +++ b/drivers/staging/greybus/svc.c @@ -511,6 +511,7 @@ static void gb_svc_process_deferred_request(struct work_struct *work) static int gb_svc_queue_deferred_request(struct gb_operation *operation) { + struct gb_svc *svc = operation->connection->private; struct gb_svc_deferred_request *dr; dr = kmalloc(sizeof(*dr), GFP_KERNEL); @@ -522,7 +523,7 @@ static int gb_svc_queue_deferred_request(struct gb_operation *operation) dr->operation = operation; INIT_WORK(&dr->work, gb_svc_process_deferred_request); - queue_work(system_unbound_wq, &dr->work); + queue_work(svc->wq, &dr->work); return 0; } @@ -532,7 +533,7 @@ static int gb_svc_queue_deferred_request(struct gb_operation *operation) * initialization on the module side. Over that, we may also need to download * the firmware first and flash that on the module. * - * In order to make other hotplug events to not wait for all this to finish, + * In order not to make other svc events wait for all this to finish, * handle most of module hotplug stuff outside of the hotplug callback, with * help of a workqueue. */ @@ -658,6 +659,7 @@ static void gb_svc_release(struct device *dev) struct gb_svc *svc = to_gb_svc(dev); ida_destroy(&svc->device_id_map); + destroy_workqueue(svc->wq); kfree(svc); } @@ -675,6 +677,12 @@ static int gb_svc_connection_init(struct gb_connection *connection) if (!svc) return -ENOMEM; + svc->wq = alloc_workqueue("%s:svc", WQ_UNBOUND, 1, dev_name(&hd->dev)); + if (!svc->wq) { + kfree(svc); + return -ENOMEM; + } + svc->dev.parent = &hd->dev; svc->dev.bus = &greybus_bus_type; svc->dev.type = &greybus_svc_type; diff --git a/drivers/staging/greybus/svc.h b/drivers/staging/greybus/svc.h index 99be0411d000..3acfa07cc73b 100644 --- a/drivers/staging/greybus/svc.h +++ b/drivers/staging/greybus/svc.h @@ -22,6 +22,7 @@ struct gb_svc { struct gb_connection *connection; enum gb_svc_state state; struct ida device_id_map; + struct workqueue_struct *wq; u16 endo_id; u8 ap_intf_id; -- 2.20.1