diff options
author | Greg Kroah-Hartman | 2014-03-25 20:54:57 -0700 |
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committer | Greg Kroah-Hartman | 2014-03-25 20:54:57 -0700 |
commit | 72099304eeb316c4b00df3ae83efe4375729bd78 (patch) | |
tree | 3d4a7dbe61ad9bbaeb767b1fb43e190901bcb70b /fs/sysfs | |
parent | b7ce40cff0b9f6597f8318fd761accd92727f61f (diff) |
Revert "sysfs, driver-core: remove unused {sysfs|device}_schedule_callback_owner()"
This reverts commit d1ba277e79889085a2faec3b68b91ce89c63f888.
As reported by Stephen, this patch breaks linux-next as a ppc patch
suddenly (after 2 years) started using this old api call. So revert it
for now, it will go away in 3.15-rc2 when we can change the PPC call to
the new api.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tejun Heo <tj@kernel.org>
Cc: Stewart Smith <stewart@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/sysfs')
-rw-r--r-- | fs/sysfs/file.c | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c index 28cc1acd5439..1b8b91b67fdb 100644 --- a/fs/sysfs/file.c +++ b/fs/sysfs/file.c @@ -453,3 +453,95 @@ void sysfs_remove_bin_file(struct kobject *kobj, kernfs_remove_by_name(kobj->sd, attr->attr.name); } EXPORT_SYMBOL_GPL(sysfs_remove_bin_file); + +struct sysfs_schedule_callback_struct { + struct list_head workq_list; + struct kobject *kobj; + void (*func)(void *); + void *data; + struct module *owner; + struct work_struct work; +}; + +static struct workqueue_struct *sysfs_workqueue; +static DEFINE_MUTEX(sysfs_workq_mutex); +static LIST_HEAD(sysfs_workq); +static void sysfs_schedule_callback_work(struct work_struct *work) +{ + struct sysfs_schedule_callback_struct *ss = container_of(work, + struct sysfs_schedule_callback_struct, work); + + (ss->func)(ss->data); + kobject_put(ss->kobj); + module_put(ss->owner); + mutex_lock(&sysfs_workq_mutex); + list_del(&ss->workq_list); + mutex_unlock(&sysfs_workq_mutex); + kfree(ss); +} + +/** + * sysfs_schedule_callback - helper to schedule a callback for a kobject + * @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 + * deadlock, since unregistration is mutually exclusive with driver + * callbacks. + * + * Instead methods can call this routine, which will attempt to allocate + * and schedule a workqueue request to call back @func with @data as its + * argument in the workqueue's process context. @kobj will be pinned + * until @func returns. + * + * Returns 0 if the request was submitted, -ENOMEM if storage could not + * be allocated, -ENODEV if a reference to @owner isn't available, + * -EAGAIN if a callback has already been scheduled for @kobj. + */ +int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *), + void *data, struct module *owner) +{ + struct sysfs_schedule_callback_struct *ss, *tmp; + + if (!try_module_get(owner)) + return -ENODEV; + + mutex_lock(&sysfs_workq_mutex); + list_for_each_entry_safe(ss, tmp, &sysfs_workq, workq_list) + if (ss->kobj == kobj) { + module_put(owner); + mutex_unlock(&sysfs_workq_mutex); + return -EAGAIN; + } + mutex_unlock(&sysfs_workq_mutex); + + if (sysfs_workqueue == NULL) { + sysfs_workqueue = create_singlethread_workqueue("sysfsd"); + if (sysfs_workqueue == NULL) { + module_put(owner); + return -ENOMEM; + } + } + + ss = kmalloc(sizeof(*ss), GFP_KERNEL); + 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); + INIT_LIST_HEAD(&ss->workq_list); + mutex_lock(&sysfs_workq_mutex); + list_add_tail(&ss->workq_list, &sysfs_workq); + mutex_unlock(&sysfs_workq_mutex); + queue_work(sysfs_workqueue, &ss->work); + return 0; +} +EXPORT_SYMBOL_GPL(sysfs_schedule_callback); |