From 107c42f138d21d80b49e6c6986cf0f6fd8e605b5 Mon Sep 17 00:00:00 2001
From: Alessandro Rubini <rubini@gnudd.com>
Date: Mon, 30 Jan 2012 01:29:07 +0100
Subject: [PATCH] core: offer generic_fops, add v_op
We will have buffers that use the default operations (the majority) and
buffers without file operations for in-kernel activities, like the
input subsystem. In the latter case we want the cdev to refuse being
openend, so NULL is reserved for that case.
Also, add v_op to the buffer, so it can support mmap.
Signed-off-by: Alessandro Rubini <rubini@gnudd.com>
Acked-by: Federico Vaga <federico.vaga@gmail.com>
---
buffers/zio-buf-kmalloc.c | 15 +---------
include/linux/zio-buffer.h | 25 +++++++---------
include/linux/zio.h | 3 ++
zio-cdev.c | 60 +++++++++++++++++++++++++++++++++-----
zio-sys.c | 9 +++++-
5 files changed, 74 insertions(+), 38 deletions(-)
diff --git a/buffers/zio-buf-kmalloc.c b/buffers/zio-buf-kmalloc.c
index 0155e29..450ead8 100644
--- a/buffers/zio-buf-kmalloc.c
+++ b/buffers/zio-buf-kmalloc.c
@@ -243,19 +243,6 @@ static const struct zio_buffer_operations zbk_buffer_ops = {
.destroy = zbk_destroy,
};
-/*
- * File operations. We only have read and write: mmap is definitely
- * not suitable here, and open/release are not needed.
- */
-
-static const struct file_operations zbk_file_ops = {
- .owner = THIS_MODULE,
- .read = zio_generic_read,
- .write = zio_generic_write,
- .poll = zio_generic_poll,
- .release = zio_generic_release,
-};
-
static struct zio_buffer_type zbk_buffer = {
.owner = THIS_MODULE,
.zattr_set = {
@@ -263,7 +250,7 @@ static struct zio_buffer_type zbk_buffer = {
},
.s_op = &zbk_sysfs_ops,
.b_op = &zbk_buffer_ops,
- .f_op = &zbk_file_ops,
+ .f_op = &zio_generic_file_operations,
};
static int __init zbk_init(void)
diff --git a/include/linux/zio-buffer.h b/include/linux/zio-buffer.h
index df987d1..7cda57b 100644
--- a/include/linux/zio-buffer.h
+++ b/include/linux/zio-buffer.h
@@ -26,26 +26,27 @@ struct zio_buffer_type {
struct module *owner;
struct list_head list; /* instances, and list lock */
struct spinlock lock;
- unsigned long flags; /* to be defined */
+ unsigned long flags;
- /* file operations (read/write etc) are buffer-specific too */
const struct zio_sysfs_operations *s_op;
const struct zio_buffer_operations *b_op;
+ /*
+ * file operations (read/write etc) are buffer-specific too, but
+ * you are strongly suggested to use zio_generic_file_operations.
+ * If the field is NULL, you'll get ENODEV when opening the cdev.
+ */
const struct file_operations *f_op;
+ const struct vm_operations *v_op;
/* default attributes for instance */
struct zio_attribute_set zattr_set;
};
#define to_zio_buf(ptr) container_of(ptr, struct zio_buffer_type, head.kobj)
-/* read and write may often be the generic ones */
-ssize_t zio_generic_read(struct file *, char __user *,
- size_t, loff_t *);
-ssize_t zio_generic_write(struct file *, const char __user *,
- size_t, loff_t *);
-unsigned int zio_generic_poll(struct file *, struct poll_table_struct *);
-int zio_generic_release(struct inode *inode, struct file *f);
+/* buffer_type->flags */
+#define ZIO_BFLAG_ALLOC_FOPS 0x00000001 /* set by zio-core */
+extern const struct file_operations zio_generic_file_operations;
int __must_check zio_register_buf(struct zio_buffer_type *zbuf,
const char *name);
@@ -141,10 +142,4 @@ struct zio_f_priv {
enum zio_cdev_type type;
};
-ssize_t zio_generic_read(struct file *f, char __user *ubuf,
- size_t count, loff_t *offp);
-ssize_t zio_generic_write(struct file *f, const char __user *ubuf,
- size_t count, loff_t *offp);
-unsigned int zio_generic_poll(struct file *f, struct poll_table_struct *w);
-
#endif /* __ZIO_BUFFER_H__ */
diff --git a/include/linux/zio.h b/include/linux/zio.h
index 588548f..eaf1627 100644
--- a/include/linux/zio.h
+++ b/include/linux/zio.h
@@ -266,6 +266,9 @@ void zio_default_buffer_exit(void);
int zio_default_trigger_init(void);
void zio_default_trigger_exit(void);
+int zio_init_buffer_fops(struct zio_buffer_type *zbuf);
+int zio_fini_buffer_fops(struct zio_buffer_type *zbuf);
+
#endif /* __ZIO_INTERNAL__ */
#endif /* __KERNEL__ */
diff --git a/zio-cdev.c b/zio-cdev.c
index 54488be..9bfbd32 100644
--- a/zio-cdev.c
+++ b/zio-cdev.c
@@ -125,9 +125,15 @@ static int zio_f_open(struct inode *ino, struct file *f)
chan = __zio_minor_to_chan(ino->i_rdev);
if (!chan) {
pr_err("ZIO: can't retrieve channel for minor %i\n", minor);
+ zio_device_put(ino->i_rdev);
return -EBUSY;
}
zbuf = chan->cset->zbuf;
+ if (!zbuf->f_op) {
+ zio_device_put(ino->i_rdev);
+ return -ENODEV;
+ }
+
f->private_data = NULL;
priv = kzalloc(sizeof(struct zio_f_priv), GFP_KERNEL);
if (!priv)
@@ -370,7 +376,7 @@ static int __zio_write_allowed(struct zio_f_priv *priv)
* work for most buffer types, and are exported for use in their
* buffer operations.
*/
-ssize_t zio_generic_read(struct file *f, char __user *ubuf,
+static ssize_t zio_generic_read(struct file *f, char __user *ubuf,
size_t count, loff_t *offp)
{
struct zio_f_priv *priv = f->private_data;
@@ -418,9 +424,8 @@ ssize_t zio_generic_read(struct file *f, char __user *ubuf,
}
return count;
}
-EXPORT_SYMBOL(zio_generic_read);
-ssize_t zio_generic_write(struct file *f, const char __user *ubuf,
+static ssize_t zio_generic_write(struct file *f, const char __user *ubuf,
size_t count, loff_t *offp)
{
struct zio_f_priv *priv = f->private_data;
@@ -475,9 +480,9 @@ ssize_t zio_generic_write(struct file *f, const char __user *ubuf,
*offp += count;
return count;
}
-EXPORT_SYMBOL(zio_generic_write);
-unsigned int zio_generic_poll(struct file *f, struct poll_table_struct *w)
+static unsigned int zio_generic_poll(struct file *f,
+ struct poll_table_struct *w)
{
struct zio_f_priv *priv = f->private_data;
struct zio_bi *bi = priv->chan->bi;
@@ -485,9 +490,8 @@ unsigned int zio_generic_poll(struct file *f, struct poll_table_struct *w)
poll_wait(f, &bi->q, w);
return __zio_read_allowed(priv) | __zio_write_allowed(priv);
}
-EXPORT_SYMBOL(zio_generic_poll);
-int zio_generic_release(struct inode *inode, struct file *f)
+static int zio_generic_release(struct inode *inode, struct file *f)
{
struct zio_f_priv *priv = f->private_data;
@@ -496,5 +500,45 @@ int zio_generic_release(struct inode *inode, struct file *f)
zio_device_put(inode->i_rdev);
return 0;
}
-EXPORT_SYMBOL(zio_generic_release);
+const struct file_operations zio_generic_file_operations = {
+ /* no owner: this template is copied over */
+ .read = zio_generic_read,
+ .write = zio_generic_write,
+ .poll = zio_generic_poll,
+ .release = zio_generic_release,
+};
+/* Export, so buffers can use it or internal function */
+EXPORT_SYMBOL(zio_generic_file_operations);
+
+/* Currently, this is a "all or nothing" choice */
+int zio_init_buffer_fops(struct zio_buffer_type *zbuf)
+{
+ struct file_operations *ops;
+
+ /* Current fops may be NULL (buffer for in-kernel data handling */
+ if (!zbuf->f_op)
+ return 0;
+ if (zbuf->f_op != &zio_generic_file_operations)
+ return 0;
+
+ /* If it's the generic ones, we must clone to fit the owner field */
+ ops = kzalloc(sizeof(*ops), GFP_KERNEL);
+ if (!ops)
+ return -ENOMEM;
+ zbuf->flags |= ZIO_BFLAG_ALLOC_FOPS;
+ *ops = zio_generic_file_operations;
+ ops->owner = zbuf->owner;
+ zbuf->f_op = ops;
+ return 0;
+}
+
+int zio_fini_buffer_fops(struct zio_buffer_type *zbuf)
+{
+ if (!(zbuf->flags & ZIO_BFLAG_ALLOC_FOPS))
+ return 0;
+ zbuf->flags &= ~ZIO_BFLAG_ALLOC_FOPS;
+ kfree(zbuf->f_op);
+ zbuf->f_op = &zio_generic_file_operations;
+ return 0;
+}
diff --git a/zio-sys.c b/zio-sys.c
index 5cd661c..107da39 100644
--- a/zio-sys.c
+++ b/zio-sys.c
@@ -1671,10 +1671,16 @@ int zio_register_buf(struct zio_buffer_type *zbuf, const char *name)
if (!zbuf || !name)
return -EINVAL;
+ err = zio_init_buffer_fops(zbuf);
+ if (err < 0)
+ return err;
+
err = zobj_register(&zstat->all_buffer_types, &zbuf->head,
ZBUF, zbuf->owner, name);
- if (err)
+ if (err) {
+ zio_fini_buffer_fops(zbuf);
return err;
+ }
zbuf->zattr_set.n_std_attr = ZATTR_STD_NUM_ZBUF;
INIT_LIST_HEAD(&zbuf->list);
spin_lock_init(&zbuf->lock);
@@ -1687,6 +1693,7 @@ void zio_unregister_buf(struct zio_buffer_type *zbuf)
{
if (!zbuf)
return;
+ zio_fini_buffer_fops(zbuf);
zobj_unregister(&zstat->all_buffer_types, &zbuf->head);
}
EXPORT_SYMBOL(zio_unregister_buf);
--
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