X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=fs%2Fsysfs%2Ffile.c;h=dc30d9e31683cd64f5dfdccc6d645bdc16c1de54;hb=3b9f0ed78cf2eb678edd60d74a4a36f5947d003d;hp=8f1ebd88b9cec02f01e36c1f02d77017578627e8;hpb=50ab1a72863b1ad4b117862bc52610f8d4535609;p=safe%2Fjmp%2Flinux-2.6 diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c index 8f1ebd8..dc30d9e 100644 --- a/fs/sysfs/file.c +++ b/fs/sysfs/file.c @@ -1,52 +1,52 @@ /* - * file.c - operations for regular (text) files. + * fs/sysfs/file.c - sysfs regular (text) file implementation + * + * Copyright (c) 2001-3 Patrick Mochel + * Copyright (c) 2007 SUSE Linux Products GmbH + * Copyright (c) 2007 Tejun Heo + * + * This file is released under the GPLv2. + * + * Please see Documentation/filesystems/sysfs.txt for more information. */ #include #include +#include +#include +#include #include #include #include #include +#include #include #include "sysfs.h" -#define to_sattr(a) container_of(a,struct subsys_attribute, attr) - -/* - * Subsystem file operations. - * These operations allow subsystems to have files that can be - * read/written. - */ -static ssize_t -subsys_attr_show(struct kobject * kobj, struct attribute * attr, char * page) +/* used in crash dumps to help with debugging */ +static char last_sysfs_file[PATH_MAX]; +void sysfs_printk_last_file(void) { - struct kset *kset = to_kset(kobj); - struct subsys_attribute * sattr = to_sattr(attr); - ssize_t ret = -EIO; - - if (sattr->show) - ret = sattr->show(kset, page); - return ret; + printk(KERN_EMERG "last sysfs file: %s\n", last_sysfs_file); } -static ssize_t -subsys_attr_store(struct kobject * kobj, struct attribute * attr, - const char * page, size_t count) -{ - struct kset *kset = to_kset(kobj); - struct subsys_attribute * sattr = to_sattr(attr); - ssize_t ret = -EIO; - - if (sattr->store) - ret = sattr->store(kset, page, count); - return ret; -} +/* + * There's one sysfs_buffer for each open file and one + * sysfs_open_dirent for each sysfs_dirent with one or more open + * files. + * + * filp->private_data points to sysfs_buffer and + * sysfs_dirent->s_attr.open points to sysfs_open_dirent. s_attr.open + * is protected by sysfs_open_dirent_lock. + */ +static DEFINE_SPINLOCK(sysfs_open_dirent_lock); -static struct sysfs_ops subsys_sysfs_ops = { - .show = subsys_attr_show, - .store = subsys_attr_store, +struct sysfs_open_dirent { + atomic_t refcnt; + atomic_t event; + wait_queue_head_t poll; + struct list_head buffers; /* goes through sysfs_buffer.list */ }; struct sysfs_buffer { @@ -57,6 +57,7 @@ struct sysfs_buffer { struct mutex mutex; int needs_read_fill; int event; + struct list_head list; }; /** @@ -73,7 +74,7 @@ struct sysfs_buffer { static int fill_read_buffer(struct dentry * dentry, struct sysfs_buffer * buffer) { struct sysfs_dirent *attr_sd = dentry->d_fsdata; - struct kobject *kobj = attr_sd->s_parent->s_elem.dir.kobj; + struct kobject *kobj = attr_sd->s_parent->s_dir.kobj; struct sysfs_ops * ops = buffer->ops; int ret = 0; ssize_t count; @@ -87,12 +88,21 @@ static int fill_read_buffer(struct dentry * dentry, struct sysfs_buffer * buffer if (!sysfs_get_active_two(attr_sd)) return -ENODEV; - buffer->event = atomic_read(&attr_sd->s_event); - count = ops->show(kobj, attr_sd->s_elem.attr.attr, buffer->page); + buffer->event = atomic_read(&attr_sd->s_attr.open->event); + count = ops->show(kobj, attr_sd->s_attr.attr, buffer->page); sysfs_put_active_two(attr_sd); - BUG_ON(count > (ssize_t)PAGE_SIZE); + /* + * The code works fine with PAGE_SIZE return but it's likely to + * indicate truncated result or overflow in normal use cases. + */ + if (count >= (ssize_t)PAGE_SIZE) { + print_symbol("fill_read_buffer: %s returned bad count\n", + (unsigned long)ops->show); + /* Try to struggle along */ + count = PAGE_SIZE - 1; + } if (count >= 0) { buffer->needs_read_fill = 0; buffer->count = count; @@ -128,13 +138,13 @@ sysfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos) ssize_t retval = 0; mutex_lock(&buffer->mutex); - if (buffer->needs_read_fill) { + if (buffer->needs_read_fill || *ppos == 0) { retval = fill_read_buffer(file->f_path.dentry,buffer); if (retval) goto out; } pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n", - __FUNCTION__, count, *ppos, buffer->page); + __func__, count, *ppos, buffer->page); retval = simple_read_from_buffer(buf, count, ppos, buffer->page, buffer->count); out: @@ -188,7 +198,7 @@ static int flush_write_buffer(struct dentry * dentry, struct sysfs_buffer * buffer, size_t count) { struct sysfs_dirent *attr_sd = dentry->d_fsdata; - struct kobject *kobj = attr_sd->s_parent->s_elem.dir.kobj; + struct kobject *kobj = attr_sd->s_parent->s_dir.kobj; struct sysfs_ops * ops = buffer->ops; int rc; @@ -196,7 +206,7 @@ flush_write_buffer(struct dentry * dentry, struct sysfs_buffer * buffer, size_t if (!sysfs_get_active_two(attr_sd)) return -ENODEV; - rc = ops->store(kobj, attr_sd->s_elem.attr.attr, buffer->page, count); + rc = ops->store(kobj, attr_sd->s_attr.attr, buffer->page, count); sysfs_put_active_two(attr_sd); @@ -237,35 +247,114 @@ sysfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t return len; } +/** + * sysfs_get_open_dirent - get or create sysfs_open_dirent + * @sd: target sysfs_dirent + * @buffer: sysfs_buffer for this instance of open + * + * If @sd->s_attr.open exists, increment its reference count; + * otherwise, create one. @buffer is chained to the buffers + * list. + * + * LOCKING: + * Kernel thread context (may sleep). + * + * RETURNS: + * 0 on success, -errno on failure. + */ +static int sysfs_get_open_dirent(struct sysfs_dirent *sd, + struct sysfs_buffer *buffer) +{ + struct sysfs_open_dirent *od, *new_od = NULL; + + retry: + spin_lock_irq(&sysfs_open_dirent_lock); + + if (!sd->s_attr.open && new_od) { + sd->s_attr.open = new_od; + new_od = NULL; + } + + od = sd->s_attr.open; + if (od) { + atomic_inc(&od->refcnt); + list_add_tail(&buffer->list, &od->buffers); + } + + spin_unlock_irq(&sysfs_open_dirent_lock); + + if (od) { + kfree(new_od); + return 0; + } + + /* not there, initialize a new one and retry */ + new_od = kmalloc(sizeof(*new_od), GFP_KERNEL); + if (!new_od) + return -ENOMEM; + + atomic_set(&new_od->refcnt, 0); + atomic_set(&new_od->event, 1); + init_waitqueue_head(&new_od->poll); + INIT_LIST_HEAD(&new_od->buffers); + goto retry; +} + +/** + * sysfs_put_open_dirent - put sysfs_open_dirent + * @sd: target sysfs_dirent + * @buffer: associated sysfs_buffer + * + * Put @sd->s_attr.open and unlink @buffer from the buffers list. + * If reference count reaches zero, disassociate and free it. + * + * LOCKING: + * None. + */ +static void sysfs_put_open_dirent(struct sysfs_dirent *sd, + struct sysfs_buffer *buffer) +{ + struct sysfs_open_dirent *od = sd->s_attr.open; + unsigned long flags; + + spin_lock_irqsave(&sysfs_open_dirent_lock, flags); + + list_del(&buffer->list); + if (atomic_dec_and_test(&od->refcnt)) + sd->s_attr.open = NULL; + else + od = NULL; + + spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags); + + kfree(od); +} + static int sysfs_open_file(struct inode *inode, struct file *file) { struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata; - struct kobject *kobj = attr_sd->s_parent->s_elem.dir.kobj; - struct sysfs_buffer * buffer; - struct sysfs_ops * ops = NULL; - int error; + struct kobject *kobj = attr_sd->s_parent->s_dir.kobj; + struct sysfs_buffer *buffer; + struct sysfs_ops *ops; + int error = -EACCES; + char *p; + + p = d_path(&file->f_path, last_sysfs_file, sizeof(last_sysfs_file)); + if (p) + memmove(last_sysfs_file, p, strlen(p) + 1); /* need attr_sd for attr and ops, its parent for kobj */ if (!sysfs_get_active_two(attr_sd)) return -ENODEV; - /* if the kobject has no ktype, then we assume that it is a subsystem - * itself, and use ops for it. - */ - if (kobj->kset && kobj->kset->ktype) - ops = kobj->kset->ktype->sysfs_ops; - else if (kobj->ktype) + /* every kobject with an attribute needs a ktype assigned */ + if (kobj->ktype && kobj->ktype->sysfs_ops) ops = kobj->ktype->sysfs_ops; - else - ops = &subsys_sysfs_ops; - - error = -EACCES; - - /* No sysfs operations, either from having no subsystem, - * or the subsystem have no operations. - */ - if (!ops) + else { + WARN(1, KERN_ERR "missing sysfs attribute operations for " + "kobject: %s\n", kobject_name(kobj)); goto err_out; + } /* File needs write support. * The inode's perms must say it's ok, @@ -298,19 +387,29 @@ static int sysfs_open_file(struct inode *inode, struct file *file) buffer->ops = ops; file->private_data = buffer; + /* make sure we have open dirent struct */ + error = sysfs_get_open_dirent(attr_sd, buffer); + if (error) + goto err_free; + /* open succeeded, put active references */ sysfs_put_active_two(attr_sd); return 0; + err_free: + kfree(buffer); err_out: sysfs_put_active_two(attr_sd); return error; } -static int sysfs_release(struct inode * inode, struct file * filp) +static int sysfs_release(struct inode *inode, struct file *filp) { + struct sysfs_dirent *sd = filp->f_path.dentry->d_fsdata; struct sysfs_buffer *buffer = filp->private_data; + sysfs_put_open_dirent(sd, buffer); + if (buffer->page) free_page((unsigned long)buffer->page); kfree(buffer); @@ -325,8 +424,7 @@ static int sysfs_release(struct inode * inode, struct file * filp) * return POLLERR|POLLPRI, and select will return the fd whether * it is waiting for read, write, or exceptions. * Once poll/select indicates that the value has changed, you - * need to close and re-open the file, as simply seeking and reading - * again will not get new data, or reset the state of 'poll'. + * need to close and re-open the file, or seek to 0 and read again. * Reminder: this only works for attributes which actively support * it, and it is not possible to test an attribute from userspace * to see if it supports poll (Neither 'poll' nor 'select' return @@ -336,27 +434,44 @@ static unsigned int sysfs_poll(struct file *filp, poll_table *wait) { struct sysfs_buffer * buffer = filp->private_data; struct sysfs_dirent *attr_sd = filp->f_path.dentry->d_fsdata; - struct kobject *kobj = attr_sd->s_parent->s_elem.dir.kobj; + struct sysfs_open_dirent *od = attr_sd->s_attr.open; /* need parent for the kobj, grab both */ if (!sysfs_get_active_two(attr_sd)) goto trigger; - poll_wait(filp, &kobj->poll, wait); + poll_wait(filp, &od->poll, wait); sysfs_put_active_two(attr_sd); - if (buffer->event != atomic_read(&attr_sd->s_event)) + if (buffer->event != atomic_read(&od->event)) goto trigger; - return 0; + return DEFAULT_POLLMASK; trigger: buffer->needs_read_fill = 1; - return POLLERR|POLLPRI; + return DEFAULT_POLLMASK|POLLERR|POLLPRI; } -void sysfs_notify(struct kobject *k, char *dir, char *attr) +void sysfs_notify_dirent(struct sysfs_dirent *sd) +{ + struct sysfs_open_dirent *od; + unsigned long flags; + + spin_lock_irqsave(&sysfs_open_dirent_lock, flags); + + od = sd->s_attr.open; + if (od) { + atomic_inc(&od->event); + wake_up_interruptible(&od->poll); + } + + spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags); +} +EXPORT_SYMBOL_GPL(sysfs_notify_dirent); + +void sysfs_notify(struct kobject *k, const char *dir, const char *attr) { struct sysfs_dirent *sd = k->sd; @@ -366,10 +481,8 @@ void sysfs_notify(struct kobject *k, char *dir, char *attr) sd = sysfs_find_dirent(sd, dir); if (sd && attr) sd = sysfs_find_dirent(sd, attr); - if (sd) { - atomic_inc(&sd->s_event); - wake_up_interruptible(&k->poll); - } + if (sd) + sysfs_notify_dirent(sd); mutex_unlock(&sysfs_mutex); } @@ -384,11 +497,10 @@ const struct file_operations sysfs_file_operations = { .poll = sysfs_poll, }; - -int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr, - int type) +int sysfs_add_file_mode(struct sysfs_dirent *dir_sd, + const struct attribute *attr, int type, mode_t amode) { - umode_t mode = (attr->mode & S_IALLUGO) | S_IFREG; + umode_t mode = (amode & S_IALLUGO) | S_IFREG; struct sysfs_addrm_cxt acxt; struct sysfs_dirent *sd; int rc; @@ -396,7 +508,7 @@ int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr, sd = sysfs_new_dirent(attr->name, mode, type); if (!sd) return -ENOMEM; - sd->s_elem.attr.attr = (void *)attr; + sd->s_attr.attr = (void *)attr; sysfs_addrm_start(&acxt, dir_sd); rc = sysfs_add_one(&acxt, sd); @@ -409,10 +521,17 @@ int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr, } +int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr, + int type) +{ + return sysfs_add_file_mode(dir_sd, attr, type, attr->mode); +} + + /** * sysfs_create_file - create an attribute file for an object. * @kobj: object we're creating for. - * @attr: atrribute descriptor. + * @attr: attribute descriptor. */ int sysfs_create_file(struct kobject * kobj, const struct attribute * attr) @@ -436,7 +555,11 @@ int sysfs_add_file_to_group(struct kobject *kobj, struct sysfs_dirent *dir_sd; int error; - dir_sd = sysfs_get_dirent(kobj->sd, group); + if (group) + dir_sd = sysfs_get_dirent(kobj->sd, group); + else + dir_sd = sysfs_get(kobj->sd); + if (!dir_sd) return -ENOENT; @@ -456,44 +579,23 @@ EXPORT_SYMBOL_GPL(sysfs_add_file_to_group); */ int sysfs_chmod_file(struct kobject *kobj, struct attribute *attr, mode_t mode) { - struct sysfs_dirent *victim_sd = NULL; - struct dentry *victim = NULL; - struct inode * inode; + struct sysfs_dirent *sd; struct iattr newattrs; int rc; - rc = -ENOENT; - victim_sd = sysfs_get_dirent(kobj->sd, attr->name); - if (!victim_sd) - goto out; + mutex_lock(&sysfs_mutex); - mutex_lock(&sysfs_rename_mutex); - victim = sysfs_get_dentry(victim_sd); - mutex_unlock(&sysfs_rename_mutex); - if (IS_ERR(victim)) { - rc = PTR_ERR(victim); - victim = NULL; + rc = -ENOENT; + sd = sysfs_find_dirent(kobj->sd, attr->name); + if (!sd) goto out; - } - - inode = victim->d_inode; - - mutex_lock(&inode->i_mutex); - - newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO); - newattrs.ia_valid = ATTR_MODE | ATTR_CTIME; - rc = notify_change(victim, &newattrs); - if (rc == 0) { - mutex_lock(&sysfs_mutex); - victim_sd->s_mode = newattrs.ia_mode; - mutex_unlock(&sysfs_mutex); - } + newattrs.ia_mode = (mode & S_IALLUGO) | (sd->s_mode & ~S_IALLUGO); + newattrs.ia_valid = ATTR_MODE; + rc = sysfs_sd_setattr(sd, &newattrs); - mutex_unlock(&inode->i_mutex); out: - dput(victim); - sysfs_put(victim_sd); + mutex_unlock(&sysfs_mutex); return rc; } EXPORT_SYMBOL_GPL(sysfs_chmod_file); @@ -524,7 +626,10 @@ void sysfs_remove_file_from_group(struct kobject *kobj, { struct sysfs_dirent *dir_sd; - dir_sd = sysfs_get_dirent(kobj->sd, group); + if (group) + dir_sd = sysfs_get_dirent(kobj->sd, group); + else + dir_sd = sysfs_get(kobj->sd); if (dir_sd) { sysfs_hash_and_remove(dir_sd, attr->name); sysfs_put(dir_sd); @@ -533,13 +638,17 @@ void sysfs_remove_file_from_group(struct kobject *kobj, EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group); struct sysfs_schedule_callback_struct { - struct kobject *kobj; + 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, @@ -548,6 +657,9 @@ static void sysfs_schedule_callback_work(struct work_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); } @@ -569,15 +681,34 @@ 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, -ENODEV if a reference to @owner isn't available. + * 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; + 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); @@ -589,7 +720,11 @@ int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *), ss->data = data; ss->owner = owner; INIT_WORK(&ss->work, sysfs_schedule_callback_work); - schedule_work(&ss->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);