From: Roger Quadros <ext-roger.quadros@xxxxxxxxx>
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 : [<c0270f08>] lr : [<c0270ef4>] 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 <ext-roger.quadros@xxxxxxxxx>
---
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
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