consolidate the reassignments of ->f_op in ->open() instances
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/drivers/char/misc.c b/drivers/char/misc.c
index 190d442..fd0f7c4 100644
--- a/drivers/char/misc.c
+++ b/drivers/char/misc.c
@@ -114,7 +114,7 @@
int minor = iminor(inode);
struct miscdevice *c;
int err = -ENODEV;
- const struct file_operations *old_fops, *new_fops = NULL;
+ const struct file_operations *new_fops = NULL;
mutex_lock(&misc_mtx);
@@ -141,17 +141,11 @@
}
err = 0;
- old_fops = file->f_op;
- file->f_op = new_fops;
+ replace_fops(file, new_fops);
if (file->f_op->open) {
file->private_data = c;
- err=file->f_op->open(inode,file);
- if (err) {
- fops_put(file->f_op);
- file->f_op = fops_get(old_fops);
- }
+ err = file->f_op->open(inode,file);
}
- fops_put(old_fops);
fail:
mutex_unlock(&misc_mtx);
return err;
diff --git a/drivers/gpu/drm/drm_fops.c b/drivers/gpu/drm/drm_fops.c
index 3f84277..22d14ec 100644
--- a/drivers/gpu/drm/drm_fops.c
+++ b/drivers/gpu/drm/drm_fops.c
@@ -148,7 +148,7 @@
struct drm_minor *minor;
int minor_id = iminor(inode);
int err = -ENODEV;
- const struct file_operations *old_fops;
+ const struct file_operations *new_fops;
DRM_DEBUG("\n");
@@ -163,18 +163,13 @@
if (drm_device_is_unplugged(dev))
goto out;
- old_fops = filp->f_op;
- filp->f_op = fops_get(dev->driver->fops);
- if (filp->f_op == NULL) {
- filp->f_op = old_fops;
+ new_fops = fops_get(dev->driver->fops);
+ if (!new_fops)
goto out;
- }
- if (filp->f_op->open && (err = filp->f_op->open(inode, filp))) {
- fops_put(filp->f_op);
- filp->f_op = fops_get(old_fops);
- }
- fops_put(old_fops);
+ replace_fops(filp, new_fops);
+ if (filp->f_op->open)
+ err = filp->f_op->open(inode, filp);
out:
mutex_unlock(&drm_global_mutex);
return err;
diff --git a/drivers/media/dvb-core/dvbdev.c b/drivers/media/dvb-core/dvbdev.c
index 401ef64..983db75 100644
--- a/drivers/media/dvb-core/dvbdev.c
+++ b/drivers/media/dvb-core/dvbdev.c
@@ -74,22 +74,15 @@
if (dvbdev && dvbdev->fops) {
int err = 0;
- const struct file_operations *old_fops;
+ const struct file_operations *new_fops;
- file->private_data = dvbdev;
- old_fops = file->f_op;
- file->f_op = fops_get(dvbdev->fops);
- if (file->f_op == NULL) {
- file->f_op = old_fops;
+ new_fops = fops_get(dvbdev->fops);
+ if (!new_fops)
goto fail;
- }
- if(file->f_op->open)
+ file->private_data = dvbdev;
+ replace_fops(file, new_fops);
+ if (file->f_op->open)
err = file->f_op->open(inode,file);
- if (err) {
- fops_put(file->f_op);
- file->f_op = fops_get(old_fops);
- }
- fops_put(old_fops);
up_read(&minor_rwsem);
mutex_unlock(&dvbdev_mutex);
return err;
diff --git a/drivers/usb/core/file.c b/drivers/usb/core/file.c
index 7421888..fe0d836 100644
--- a/drivers/usb/core/file.c
+++ b/drivers/usb/core/file.c
@@ -29,27 +29,19 @@
static int usb_open(struct inode * inode, struct file * file)
{
- int minor = iminor(inode);
- const struct file_operations *c;
int err = -ENODEV;
- const struct file_operations *old_fops, *new_fops = NULL;
+ const struct file_operations *new_fops;
down_read(&minor_rwsem);
- c = usb_minors[minor];
+ new_fops = fops_get(usb_minors[iminor(inode)]);
- if (!c || !(new_fops = fops_get(c)))
+ if (!new_fops)
goto done;
- old_fops = file->f_op;
- file->f_op = new_fops;
+ replace_fops(file, new_fops);
/* Curiouser and curiouser... NULL ->open() as "no device" ? */
if (file->f_op->open)
err = file->f_op->open(inode,file);
- if (err) {
- fops_put(file->f_op);
- file->f_op = fops_get(old_fops);
- }
- fops_put(old_fops);
done:
up_read(&minor_rwsem);
return err;
diff --git a/fs/char_dev.c b/fs/char_dev.c
index afc2bb6..94b5f60 100644
--- a/fs/char_dev.c
+++ b/fs/char_dev.c
@@ -368,6 +368,7 @@
*/
static int chrdev_open(struct inode *inode, struct file *filp)
{
+ const struct file_operations *fops;
struct cdev *p;
struct cdev *new = NULL;
int ret = 0;
@@ -400,10 +401,11 @@
return ret;
ret = -ENXIO;
- filp->f_op = fops_get(p->ops);
- if (!filp->f_op)
+ fops = fops_get(p->ops);
+ if (!fops)
goto out_cdev_put;
+ replace_fops(filp, fops);
if (filp->f_op->open) {
ret = filp->f_op->open(inode, filp);
if (ret)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index d80c243..b09e4e1 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1875,6 +1875,17 @@
(((fops) && try_module_get((fops)->owner) ? (fops) : NULL))
#define fops_put(fops) \
do { if (fops) module_put((fops)->owner); } while(0)
+/*
+ * This one is to be used *ONLY* from ->open() instances.
+ * fops must be non-NULL, pinned down *and* module dependencies
+ * should be sufficient to pin the caller down as well.
+ */
+#define replace_fops(f, fops) \
+ do { \
+ struct file *__file = (f); \
+ fops_put(__file->f_op); \
+ BUG_ON(!(__file->f_op = (fops))); \
+ } while(0)
extern int register_filesystem(struct file_system_type *);
extern int unregister_filesystem(struct file_system_type *);
diff --git a/sound/core/sound.c b/sound/core/sound.c
index f002bd9..437c25e 100644
--- a/sound/core/sound.c
+++ b/sound/core/sound.c
@@ -153,7 +153,7 @@
{
unsigned int minor = iminor(inode);
struct snd_minor *mptr = NULL;
- const struct file_operations *old_fops;
+ const struct file_operations *new_fops;
int err = 0;
if (minor >= ARRAY_SIZE(snd_minors))
@@ -167,24 +167,14 @@
return -ENODEV;
}
}
- old_fops = file->f_op;
- file->f_op = fops_get(mptr->f_ops);
- if (file->f_op == NULL) {
- file->f_op = old_fops;
- err = -ENODEV;
- }
+ new_fops = fops_get(mptr->f_ops);
mutex_unlock(&sound_mutex);
- if (err < 0)
- return err;
+ if (!new_fops)
+ return -ENODEV;
+ replace_fops(file, new_fops);
- if (file->f_op->open) {
+ if (file->f_op->open)
err = file->f_op->open(inode, file);
- if (err) {
- fops_put(file->f_op);
- file->f_op = fops_get(old_fops);
- }
- }
- fops_put(old_fops);
return err;
}
diff --git a/sound/sound_core.c b/sound/sound_core.c
index 45759f4..11e953a 100644
--- a/sound/sound_core.c
+++ b/sound/sound_core.c
@@ -626,31 +626,20 @@
if (s)
new_fops = fops_get(s->unit_fops);
}
+ spin_unlock(&sound_loader_lock);
if (new_fops) {
/*
* We rely upon the fact that we can't be unloaded while the
- * subdriver is there, so if ->open() is successful we can
- * safely drop the reference counter and if it is not we can
- * revert to old ->f_op. Ugly, indeed, but that's the cost of
- * switching ->f_op in the first place.
+ * subdriver is there.
*/
int err = 0;
- const struct file_operations *old_fops = file->f_op;
- file->f_op = new_fops;
- spin_unlock(&sound_loader_lock);
+ replace_fops(file, new_fops);
if (file->f_op->open)
err = file->f_op->open(inode,file);
- if (err) {
- fops_put(file->f_op);
- file->f_op = fops_get(old_fops);
- }
-
- fops_put(old_fops);
return err;
}
- spin_unlock(&sound_loader_lock);
return -ENODEV;
}