diff options
| author | Frank Munzert <munzert@de.ibm.com> | 2008-04-17 07:46:06 +0200 |
|---|---|---|
| committer | Heiko Carstens <heiko.carstens@de.ibm.com> | 2008-04-17 07:46:59 +0200 |
| commit | a695f16729e00995fe72baf0e8bee4bf9c232ae0 (patch) | |
| tree | 2fddf1722972564e33eedbedf9010bdd9735a74d | |
| parent | 92bf435f383a6193d59c687ce87ccca3529c68a1 (diff) | |
[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 <munzert@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
| -rw-r--r-- | drivers/s390/char/vmur.c | 24 | ||||
| -rw-r--r-- | drivers/s390/char/vmur.h | 4 |
2 files changed, 20 insertions, 8 deletions
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; diff --git a/drivers/s390/char/vmur.h b/drivers/s390/char/vmur.h index fa959644735..fa320ad4593 100644 --- a/drivers/s390/char/vmur.h +++ b/drivers/s390/char/vmur.h @@ -62,7 +62,6 @@ struct file_control_block { struct urdev { struct ccw_device *cdev; /* Backpointer to ccw device */ struct mutex io_mutex; /* Serialises device IO */ - struct mutex open_mutex; /* Serialises access to device */ struct completion *io_done; /* do_ur_io waits; irq completes */ struct device *device; struct cdev *char_device; @@ -71,6 +70,9 @@ struct urdev { int class; /* VM device class */ int io_request_rc; /* return code from I/O request */ atomic_t ref_count; /* reference counter */ + wait_queue_head_t wait; /* wait queue to serialize open */ + int open_flag; /* "urdev is open" flag */ + spinlock_t open_lock; /* serialize critical sections */ }; /* |