From a695f16729e00995fe72baf0e8bee4bf9c232ae0 Mon Sep 17 00:00:00 2001 From: Frank Munzert Date: Thu, 17 Apr 2008 07:46:06 +0200 Subject: [S390] vmur: Use wait queue instead of mutex to serialize open If user space opens a unit record device node then vmur is leaving the kernel with lock open_mutex still held to prevent other processes from opening the device simultaneously. This causes lockdep to complain about a lock held when returning to user space. Now the mutex is replaced by a wait queue to serialize device open. Signed-off-by: Frank Munzert Signed-off-by: Martin Schwidefsky Signed-off-by: Heiko Carstens --- drivers/s390/char/vmur.c | 24 +++++++++++++++++------- 1 file changed, 17 insertions(+), 7 deletions(-) (limited to 'drivers/s390/char/vmur.c') diff --git a/drivers/s390/char/vmur.c b/drivers/s390/char/vmur.c index 7689b500a10..83ae9a852f0 100644 --- a/drivers/s390/char/vmur.c +++ b/drivers/s390/char/vmur.c @@ -100,7 +100,8 @@ static struct urdev *urdev_alloc(struct ccw_device *cdev) urd->reclen = cdev->id.driver_info; ccw_device_get_id(cdev, &urd->dev_id); mutex_init(&urd->io_mutex); - mutex_init(&urd->open_mutex); + init_waitqueue_head(&urd->wait); + spin_lock_init(&urd->open_lock); atomic_set(&urd->ref_count, 1); urd->cdev = cdev; get_device(&cdev->dev); @@ -678,17 +679,21 @@ static int ur_open(struct inode *inode, struct file *file) if (!urd) return -ENXIO; - if (file->f_flags & O_NONBLOCK) { - if (!mutex_trylock(&urd->open_mutex)) { + spin_lock(&urd->open_lock); + while (urd->open_flag) { + spin_unlock(&urd->open_lock); + if (file->f_flags & O_NONBLOCK) { rc = -EBUSY; goto fail_put; } - } else { - if (mutex_lock_interruptible(&urd->open_mutex)) { + if (wait_event_interruptible(urd->wait, urd->open_flag == 0)) { rc = -ERESTARTSYS; goto fail_put; } + spin_lock(&urd->open_lock); } + urd->open_flag++; + spin_unlock(&urd->open_lock); TRACE("ur_open\n"); @@ -720,7 +725,9 @@ static int ur_open(struct inode *inode, struct file *file) fail_urfile_free: urfile_free(urf); fail_unlock: - mutex_unlock(&urd->open_mutex); + spin_lock(&urd->open_lock); + urd->open_flag--; + spin_unlock(&urd->open_lock); fail_put: urdev_put(urd); return rc; @@ -731,7 +738,10 @@ static int ur_release(struct inode *inode, struct file *file) struct urfile *urf = file->private_data; TRACE("ur_release\n"); - mutex_unlock(&urf->urd->open_mutex); + spin_lock(&urf->urd->open_lock); + urf->urd->open_flag--; + spin_unlock(&urf->urd->open_lock); + wake_up_interruptible(&urf->urd->wait); urdev_put(urf->urd); urfile_free(urf); return 0; -- cgit v1.2.3-70-g09d2