Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 447 insertions, 0 deletions

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
new file mode 100644
index 000000000000..352f966a1174
--- /dev/null
+++ b/fs/sysfs/file.c
@@ -0,0 +1,447 @@
+/*
+ * file.c - operations for regular (text) files.
+ */
+
+#include <linux/module.h>
+#include <linux/dnotify.h>
+#include <linux/kobject.h>
+#include <asm/uaccess.h>
+#include <asm/semaphore.h>
+
+#include "sysfs.h"
+
+#define to_subsys(k) container_of(k,struct subsystem,kset.kobj)
+#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)
+{
+        struct subsystem * s = to_subsys(kobj);
+        struct subsys_attribute * sattr = to_sattr(attr);
+        ssize_t ret = 0;
+
+        if (sattr->show)
+                ret = sattr->show(s,page);
+        return ret;
+}
+
+static ssize_t 
+subsys_attr_store(struct kobject * kobj, struct attribute * attr, 
+                  const char * page, size_t count)
+{
+        struct subsystem * s = to_subsys(kobj);
+        struct subsys_attribute * sattr = to_sattr(attr);
+        ssize_t ret = 0;
+
+        if (sattr->store)
+                ret = sattr->store(s,page,count);
+        return ret;
+}
+
+static struct sysfs_ops subsys_sysfs_ops = {
+        .show   = subsys_attr_show,
+        .store  = subsys_attr_store,
+};
+
+
+struct sysfs_buffer {
+        size_t                  count;
+        loff_t                  pos;
+        char                    * page;
+        struct sysfs_ops        * ops;
+        struct semaphore        sem;
+        int                     needs_read_fill;
+};
+
+
+/**
+ *      fill_read_buffer - allocate and fill buffer from object.
+ *      @dentry:        dentry pointer.
+ *      @buffer:        data buffer for file.
+ *
+ *      Allocate @buffer->page, if it hasn't been already, then call the
+ *      kobject's show() method to fill the buffer with this attribute's 
+ *      data. 
+ *      This is called only once, on the file's first read. 
+ */
+static int fill_read_buffer(struct dentry * dentry, struct sysfs_buffer * buffer)
+{
+        struct attribute * attr = to_attr(dentry);
+        struct kobject * kobj = to_kobj(dentry->d_parent);
+        struct sysfs_ops * ops = buffer->ops;
+        int ret = 0;
+        ssize_t count;
+
+        if (!buffer->page)
+                buffer->page = (char *) get_zeroed_page(GFP_KERNEL);
+        if (!buffer->page)
+                return -ENOMEM;
+
+        count = ops->show(kobj,attr,buffer->page);
+        buffer->needs_read_fill = 0;
+        BUG_ON(count > (ssize_t)PAGE_SIZE);
+        if (count >= 0)
+                buffer->count = count;
+        else
+                ret = count;
+        return ret;
+}
+
+
+/**
+ *      flush_read_buffer - push buffer to userspace.
+ *      @buffer:        data buffer for file.
+ *      @userbuf:       user-passed buffer.
+ *      @count:         number of bytes requested.
+ *      @ppos:          file position.
+ *
+ *      Copy the buffer we filled in fill_read_buffer() to userspace.
+ *      This is done at the reader's leisure, copying and advancing 
+ *      the amount they specify each time.
+ *      This may be called continuously until the buffer is empty.
+ */
+static int flush_read_buffer(struct sysfs_buffer * buffer, char __user * buf,
+                             size_t count, loff_t * ppos)
+{
+        int error;
+
+        if (*ppos > buffer->count)
+                return 0;
+
+        if (count > (buffer->count - *ppos))
+                count = buffer->count - *ppos;
+
+        error = copy_to_user(buf,buffer->page + *ppos,count);
+        if (!error)
+                *ppos += count;
+        return error ? -EFAULT : count;
+}
+
+/**
+ *      sysfs_read_file - read an attribute. 
+ *      @file:  file pointer.
+ *      @buf:   buffer to fill.
+ *      @count: number of bytes to read.
+ *      @ppos:  starting offset in file.
+ *
+ *      Userspace wants to read an attribute file. The attribute descriptor
+ *      is in the file's ->d_fsdata. The target object is in the directory's
+ *      ->d_fsdata.
+ *
+ *      We call fill_read_buffer() to allocate and fill the buffer from the
+ *      object's show() method exactly once (if the read is happening from
+ *      the beginning of the file). That should fill the entire buffer with
+ *      all the data the object has to offer for that attribute.
+ *      We then call flush_read_buffer() to copy the buffer to userspace
+ *      in the increments specified.
+ */
+
+static ssize_t
+sysfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos)
+{
+        struct sysfs_buffer * buffer = file->private_data;
+        ssize_t retval = 0;
+
+        down(&buffer->sem);
+        if (buffer->needs_read_fill) {
+                if ((retval = fill_read_buffer(file->f_dentry,buffer)))
+                        goto out;
+        }
+        pr_debug("%s: count = %d, ppos = %lld, buf = %s\n",
+                 __FUNCTION__,count,*ppos,buffer->page);
+        retval = flush_read_buffer(buffer,buf,count,ppos);
+out:
+        up(&buffer->sem);
+        return retval;
+}
+
+
+/**
+ *      fill_write_buffer - copy buffer from userspace.
+ *      @buffer:        data buffer for file.
+ *      @userbuf:       data from user.
+ *      @count:         number of bytes in @userbuf.
+ *
+ *      Allocate @buffer->page if it hasn't been already, then
+ *      copy the user-supplied buffer into it.
+ */
+
+static int 
+fill_write_buffer(struct sysfs_buffer * buffer, const char __user * buf, size_t count)
+{
+        int error;
+
+        if (!buffer->page)
+                buffer->page = (char *)get_zeroed_page(GFP_KERNEL);
+        if (!buffer->page)
+                return -ENOMEM;
+
+        if (count >= PAGE_SIZE)
+                count = PAGE_SIZE - 1;
+        error = copy_from_user(buffer->page,buf,count);
+        buffer->needs_read_fill = 1;
+        return error ? -EFAULT : count;
+}
+
+
+/**
+ *      flush_write_buffer - push buffer to kobject.
+ *      @file:          file pointer.
+ *      @buffer:        data buffer for file.
+ *
+ *      Get the correct pointers for the kobject and the attribute we're
+ *      dealing with, then call the store() method for the attribute, 
+ *      passing the buffer that we acquired in fill_write_buffer().
+ */
+
+static int 
+flush_write_buffer(struct dentry * dentry, struct sysfs_buffer * buffer, size_t count)
+{
+        struct attribute * attr = to_attr(dentry);
+        struct kobject * kobj = to_kobj(dentry->d_parent);
+        struct sysfs_ops * ops = buffer->ops;
+
+        return ops->store(kobj,attr,buffer->page,count);
+}
+
+
+/**
+ *      sysfs_write_file - write an attribute.
+ *      @file:  file pointer
+ *      @buf:   data to write
+ *      @count: number of bytes
+ *      @ppos:  starting offset
+ *
+ *      Similar to sysfs_read_file(), though working in the opposite direction.
+ *      We allocate and fill the data from the user in fill_write_buffer(),
+ *      then push it to the kobject in flush_write_buffer().
+ *      There is no easy way for us to know if userspace is only doing a partial
+ *      write, so we don't support them. We expect the entire buffer to come
+ *      on the first write. 
+ *      Hint: if you're writing a value, first read the file, modify only the
+ *      the value you're changing, then write entire buffer back. 
+ */
+
+static ssize_t
+sysfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
+{
+        struct sysfs_buffer * buffer = file->private_data;
+        ssize_t len;
+
+        down(&buffer->sem);
+        len = fill_write_buffer(buffer, buf, count);
+        if (len > 0)
+                len = flush_write_buffer(file->f_dentry, buffer, len);
+        if (len > 0)
+                *ppos += len;
+        up(&buffer->sem);
+        return len;
+}
+
+static int check_perm(struct inode * inode, struct file * file)
+{
+        struct kobject *kobj = sysfs_get_kobject(file->f_dentry->d_parent);
+        struct attribute * attr = to_attr(file->f_dentry);
+        struct sysfs_buffer * buffer;
+        struct sysfs_ops * ops = NULL;
+        int error = 0;
+
+        if (!kobj || !attr)
+                goto Einval;
+
+        /* Grab the module reference for this attribute if we have one */
+        if (!try_module_get(attr->owner)) {
+                error = -ENODEV;
+                goto Done;
+        }
+
+        /* 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)
+                ops = kobj->ktype->sysfs_ops;
+        else
+                ops = &subsys_sysfs_ops;
+
+        /* No sysfs operations, either from having no subsystem,
+         * or the subsystem have no operations.
+         */
+        if (!ops)
+                goto Eaccess;
+
+        /* File needs write support.
+         * The inode's perms must say it's ok, 
+         * and we must have a store method.
+         */
+        if (file->f_mode & FMODE_WRITE) {
+
+                if (!(inode->i_mode & S_IWUGO) || !ops->store)
+                        goto Eaccess;
+
+        }
+
+        /* File needs read support.
+         * The inode's perms must say it's ok, and we there
+         * must be a show method for it.
+         */
+        if (file->f_mode & FMODE_READ) {
+                if (!(inode->i_mode & S_IRUGO) || !ops->show)
+                        goto Eaccess;
+        }
+
+        /* No error? Great, allocate a buffer for the file, and store it
+         * it in file->private_data for easy access.
+         */
+        buffer = kmalloc(sizeof(struct sysfs_buffer),GFP_KERNEL);
+        if (buffer) {
+                memset(buffer,0,sizeof(struct sysfs_buffer));
+                init_MUTEX(&buffer->sem);
+                buffer->needs_read_fill = 1;
+                buffer->ops = ops;
+                file->private_data = buffer;
+        } else
+                error = -ENOMEM;
+        goto Done;
+
+ Einval:
+        error = -EINVAL;
+        goto Done;
+ Eaccess:
+        error = -EACCES;
+        module_put(attr->owner);
+ Done:
+        if (error && kobj)
+                kobject_put(kobj);
+        return error;
+}
+
+static int sysfs_open_file(struct inode * inode, struct file * filp)
+{
+        return check_perm(inode,filp);
+}
+
+static int sysfs_release(struct inode * inode, struct file * filp)
+{
+        struct kobject * kobj = to_kobj(filp->f_dentry->d_parent);
+        struct attribute * attr = to_attr(filp->f_dentry);
+        struct module * owner = attr->owner;
+        struct sysfs_buffer * buffer = filp->private_data;
+
+        if (kobj) 
+                kobject_put(kobj);
+        /* After this point, attr should not be accessed. */
+        module_put(owner);
+
+        if (buffer) {
+                if (buffer->page)
+                        free_page((unsigned long)buffer->page);
+                kfree(buffer);
+        }
+        return 0;
+}
+
+struct file_operations sysfs_file_operations = {
+        .read           = sysfs_read_file,
+        .write          = sysfs_write_file,
+        .llseek         = generic_file_llseek,
+        .open           = sysfs_open_file,
+        .release        = sysfs_release,
+};
+
+
+int sysfs_add_file(struct dentry * dir, const struct attribute * attr, int type)
+{
+        struct sysfs_dirent * parent_sd = dir->d_fsdata;
+        umode_t mode = (attr->mode & S_IALLUGO) | S_IFREG;
+        int error = 0;
+
+        down(&dir->d_inode->i_sem);
+        error = sysfs_make_dirent(parent_sd, NULL, (void *) attr, mode, type);
+        up(&dir->d_inode->i_sem);
+
+        return error;
+}
+
+
+/**
+ *      sysfs_create_file - create an attribute file for an object.
+ *      @kobj:  object we're creating for. 
+ *      @attr:  atrribute descriptor.
+ */
+
+int sysfs_create_file(struct kobject * kobj, const struct attribute * attr)
+{
+        BUG_ON(!kobj || !kobj->dentry || !attr);
+
+        return sysfs_add_file(kobj->dentry, attr, SYSFS_KOBJ_ATTR);
+
+}
+
+
+/**
+ * sysfs_update_file - update the modified timestamp on an object attribute.
+ * @kobj: object we're acting for.
+ * @attr: attribute descriptor.
+ *
+ * Also call dnotify for the dentry, which lots of userspace programs
+ * use.
+ */
+int sysfs_update_file(struct kobject * kobj, const struct attribute * attr)
+{
+        struct dentry * dir = kobj->dentry;
+        struct dentry * victim;
+        int res = -ENOENT;
+
+        down(&dir->d_inode->i_sem);
+        victim = sysfs_get_dentry(dir, attr->name);
+        if (!IS_ERR(victim)) {
+                /* make sure dentry is really there */
+                if (victim->d_inode && 
+                    (victim->d_parent->d_inode == dir->d_inode)) {
+                        victim->d_inode->i_mtime = CURRENT_TIME;
+                        dnotify_parent(victim, DN_MODIFY);
+
+                        /**
+                         * Drop reference from initial sysfs_get_dentry().
+                         */
+                        dput(victim);
+                        res = 0;
+                } else
+                        d_drop(victim);
+                
+                /**
+                 * Drop the reference acquired from sysfs_get_dentry() above.
+                 */
+                dput(victim);
+        }
+        up(&dir->d_inode->i_sem);
+
+        return res;
+}
+
+
+/**
+ *      sysfs_remove_file - remove an object attribute.
+ *      @kobj:  object we're acting for.
+ *      @attr:  attribute descriptor.
+ *
+ *      Hash the attribute name and kill the victim.
+ */
+
+void sysfs_remove_file(struct kobject * kobj, const struct attribute * attr)
+{
+        sysfs_hash_and_remove(kobj->dentry,attr->name);
+}
+
+
+EXPORT_SYMBOL_GPL(sysfs_create_file);
+EXPORT_SYMBOL_GPL(sysfs_remove_file);
+EXPORT_SYMBOL_GPL(sysfs_update_file);
+