From 523ded71de0c5e66973335bf99a80edfda9f401b Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Thu, 26 Apr 2007 00:12:04 -0700 Subject: [PATCH] device_schedule_callback() needs a module reference This patch (as896b) fixes an oversight in the design of device_schedule_callback(). It is necessary to acquire a reference to the module owning the callback routine, to prevent the module from being unloaded before the callback can run. Signed-off-by: Alan Stern Cc: Satyam Sharma Cc: Neil Brown Cc: Cornelia Huck Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- drivers/base/core.c | 16 ++++++++++------ fs/sysfs/file.c | 14 +++++++++++--- include/linux/device.h | 8 ++++++-- include/linux/sysfs.h | 4 ++-- 4 files changed, 29 insertions(+), 13 deletions(-) diff --git a/drivers/base/core.c b/drivers/base/core.c index f69305c726..8aa090da1c 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -480,9 +480,10 @@ void device_remove_bin_file(struct device *dev, struct bin_attribute *attr) EXPORT_SYMBOL_GPL(device_remove_bin_file); /** - * device_schedule_callback - helper to schedule a callback for a device + * device_schedule_callback_owner - helper to schedule a callback for a device * @dev: device. * @func: callback function to invoke later. + * @owner: module owning the callback routine * * Attribute methods must not unregister themselves or their parent device * (which would amount to the same thing). Attempts to do so will deadlock, @@ -493,20 +494,23 @@ EXPORT_SYMBOL_GPL(device_remove_bin_file); * argument in the workqueue's process context. @dev will be pinned until * @func returns. * + * This routine is usually called via the inline device_schedule_callback(), + * which automatically sets @owner to THIS_MODULE. + * * Returns 0 if the request was submitted, -ENOMEM if storage could not - * be allocated. + * be allocated, -ENODEV if a reference to @owner isn't available. * * NOTE: This routine won't work if CONFIG_SYSFS isn't set! It uses an * underlying sysfs routine (since it is intended for use by attribute * methods), and if sysfs isn't available you'll get nothing but -ENOSYS. */ -int device_schedule_callback(struct device *dev, - void (*func)(struct device *)) +int device_schedule_callback_owner(struct device *dev, + void (*func)(struct device *), struct module *owner) { return sysfs_schedule_callback(&dev->kobj, - (void (*)(void *)) func, dev); + (void (*)(void *)) func, dev, owner); } -EXPORT_SYMBOL_GPL(device_schedule_callback); +EXPORT_SYMBOL_GPL(device_schedule_callback_owner); static void klist_children_get(struct klist_node *n) { diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c index fc4633378d..db0413a411 100644 --- a/fs/sysfs/file.c +++ b/fs/sysfs/file.c @@ -633,6 +633,7 @@ struct sysfs_schedule_callback_struct { struct kobject *kobj; void (*func)(void *); void *data; + struct module *owner; struct work_struct work; }; @@ -643,6 +644,7 @@ static void sysfs_schedule_callback_work(struct work_struct *work) (ss->func)(ss->data); kobject_put(ss->kobj); + module_put(ss->owner); kfree(ss); } @@ -651,6 +653,7 @@ static void sysfs_schedule_callback_work(struct work_struct *work) * @kobj: object we're acting for. * @func: callback function to invoke later. * @data: argument to pass to @func. + * @owner: module owning the callback code * * sysfs attribute methods must not unregister themselves or their parent * kobject (which would amount to the same thing). Attempts to do so will @@ -663,20 +666,25 @@ static void sysfs_schedule_callback_work(struct work_struct *work) * until @func returns. * * Returns 0 if the request was submitted, -ENOMEM if storage could not - * be allocated. + * be allocated, -ENODEV if a reference to @owner isn't available. */ int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *), - void *data) + void *data, struct module *owner) { struct sysfs_schedule_callback_struct *ss; + if (!try_module_get(owner)) + return -ENODEV; ss = kmalloc(sizeof(*ss), GFP_KERNEL); - if (!ss) + if (!ss) { + module_put(owner); return -ENOMEM; + } kobject_get(kobj); ss->kobj = kobj; ss->func = func; ss->data = data; + ss->owner = owner; INIT_WORK(&ss->work, sysfs_schedule_callback_work); schedule_work(&ss->work); return 0; diff --git a/include/linux/device.h b/include/linux/device.h index af603a1376..8511d14071 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -367,8 +367,12 @@ extern int __must_check device_create_bin_file(struct device *dev, struct bin_attribute *attr); extern void device_remove_bin_file(struct device *dev, struct bin_attribute *attr); -extern int device_schedule_callback(struct device *dev, - void (*func)(struct device *)); +extern int device_schedule_callback_owner(struct device *dev, + void (*func)(struct device *), struct module *owner); + +/* This is a macro to avoid include problems with THIS_MODULE */ +#define device_schedule_callback(dev, func) \ + device_schedule_callback_owner(dev, func, THIS_MODULE) /* device resource management */ typedef void (*dr_release_t)(struct device *dev, void *res); diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h index fea9a6b3fb..7d5d1ec95c 100644 --- a/include/linux/sysfs.h +++ b/include/linux/sysfs.h @@ -80,7 +80,7 @@ struct sysfs_ops { #ifdef CONFIG_SYSFS extern int sysfs_schedule_callback(struct kobject *kobj, - void (*func)(void *), void *data); + void (*func)(void *), void *data, struct module *owner); extern int __must_check sysfs_create_dir(struct kobject *, struct dentry *); @@ -137,7 +137,7 @@ extern int __must_check sysfs_init(void); #else /* CONFIG_SYSFS */ static inline int sysfs_schedule_callback(struct kobject *kobj, - void (*func)(void *), void *data) + void (*func)(void *), void *data, struct module *owner) { return -ENOSYS; } -- 2.39.5