Return-Path: Message-ID: <49F05193.7070609@nokia.com> Date: Thu, 23 Apr 2009 14:31:31 +0300 From: Roger Quadros MIME-Version: 1.0 To: Marcel Holtmann , linux-bluetooth@vger.kernel.org Subject: [RFC][PATCH] bluetooth: hci_sysfs: Ensure sysfs add/del is pre-empt safe Content-Type: text/plain; charset=ISO-8859-1; format=flowed List-ID: From: Roger Quadros Date: Thu, 23 Apr 2009 14:05:19 +0300 Subject: [PATCH] bluetooth: hci_sysfs: Ensure sysfs add/del is pre-empt safe Uses different work_struct variables for add_conn() and del_conn(). Uses single work queue instead of two for adding and deleting connections. It eliminates the following error on a pre-emptible kernel. [ 204.358032] Unable to handle kernel NULL pointer dereference at virtual address 0000000c [ 204.370697] pgd = c0004000 [ 204.373443] [0000000c] *pgd=00000000 [ 204.378601] Internal error: Oops: 17 [#1] PREEMPT [ 204.383361] Modules linked in: vfat fat rfcomm sco l2cap sd_mod scsi_mod iphb pvr2d drm omaplfb ps [ 204.438537] CPU: 0 Not tainted (2.6.28-maemo2 #1) [ 204.443664] PC is at klist_put+0x2c/0xb4 [ 204.447601] LR is at klist_put+0x18/0xb4 [ 204.451568] pc : [] lr : [] psr: a0000113 [ 204.451568] sp : cf1b3f10 ip : cf1b3f10 fp : cf1b3f2c [ 204.463104] r10: 00000000 r9 : 00000000 r8 : bf08029c [ 204.468353] r7 : c7869200 r6 : cfbe2690 r5 : c78692c8 r4 : 00000001 [ 204.474945] r3 : 00000001 r2 : cf1b2000 r1 : 00000001 r0 : 00000000 [ 204.481506] Flags: NzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment kernel [ 204.488861] Control: 10c5387d Table: 887fc018 DAC: 00000017 [ 204.494628] Process btdelconn (pid: 515, stack limit = 0xcf1b22e0) Signed-off-by: Roger Quadros --- include/net/bluetooth/hci_core.h | 3 ++- net/bluetooth/hci_sysfs.c | 37 ++++++++++++++++--------------------- 2 files changed, 18 insertions(+), 22 deletions(-) diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h index 30a5be8..988e8cb 100644 --- a/include/net/bluetooth/hci_core.h +++ b/include/net/bluetooth/hci_core.h @@ -180,7 +180,8 @@ struct hci_conn { struct timer_list disc_timer; struct timer_list idle_timer; - struct work_struct work; + struct work_struct work_add; + struct work_struct work_del; struct device dev; diff --git a/net/bluetooth/hci_sysfs.c b/net/bluetooth/hci_sysfs.c index 1a1f916..8cddc1c 100644 --- a/net/bluetooth/hci_sysfs.c +++ b/net/bluetooth/hci_sysfs.c @@ -9,8 +9,7 @@ struct class *bt_class = NULL; EXPORT_SYMBOL_GPL(bt_class); -static struct workqueue_struct *btaddconn; -static struct workqueue_struct *btdelconn; +static struct workqueue_struct *btworkq; static inline char *link_typetostr(int type) { @@ -88,9 +87,10 @@ static struct device_type bt_link = { static void add_conn(struct work_struct *work) { - struct hci_conn *conn = container_of(work, struct hci_conn, work); + struct hci_conn *conn = container_of(work, struct hci_conn, work_add); - flush_workqueue(btdelconn); + /* ensure previous add/del is complete */ + flush_workqueue(btworkq); if (device_add(&conn->dev) < 0) { BT_ERR("Failed to register connection device"); @@ -114,9 +114,9 @@ void hci_conn_add_sysfs(struct hci_conn *conn) device_initialize(&conn->dev); - INIT_WORK(&conn->work, add_conn); + INIT_WORK(&conn->work_add, add_conn); - queue_work(btaddconn, &conn->work); + queue_work(btworkq, &conn->work_add); } /* @@ -131,9 +131,12 @@ static int __match_tty(struct device *dev, void *data) static void del_conn(struct work_struct *work) { - struct hci_conn *conn = container_of(work, struct hci_conn, work); + struct hci_conn *conn = container_of(work, struct hci_conn, work_del); struct hci_dev *hdev = conn->hdev; + /* ensure previous add/del is complete */ + flush_workqueue(btworkq); + while (1) { struct device *dev; @@ -156,9 +159,9 @@ void hci_conn_del_sysfs(struct hci_conn *conn) if (!device_is_registered(&conn->dev)) return; - INIT_WORK(&conn->work, del_conn); + INIT_WORK(&conn->work_del, del_conn); - queue_work(btdelconn, &conn->work); + queue_work(btworkq, &conn->work_del); } static inline char *host_typetostr(int type) @@ -435,20 +438,13 @@ void hci_unregister_sysfs(struct hci_dev *hdev) int __init bt_sysfs_init(void) { - btaddconn = create_singlethread_workqueue("btaddconn"); - if (!btaddconn) - return -ENOMEM; - - btdelconn = create_singlethread_workqueue("btdelconn"); - if (!btdelconn) { - destroy_workqueue(btaddconn); + btworkq = create_singlethread_workqueue("btworkq"); + if (!btworkq) return -ENOMEM; - } bt_class = class_create(THIS_MODULE, "bluetooth"); if (IS_ERR(bt_class)) { - destroy_workqueue(btdelconn); - destroy_workqueue(btaddconn); + destroy_workqueue(btworkq); return PTR_ERR(bt_class); } @@ -457,8 +453,7 @@ int __init bt_sysfs_init(void) void bt_sysfs_cleanup(void) { - destroy_workqueue(btaddconn); - destroy_workqueue(btdelconn); + destroy_workqueue(btworkq); class_destroy(bt_class); } -- 1.5.6.3