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debugfs: unproxify files created through debugfs_create_bool()

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Currently, the struct file_operations fops_bool associated with files
created through the debugfs_create_bool() helpers are not file
lifetime aware.

Thus, a lifetime managing proxy is created around fops_bool each time such
a file is opened which is an unnecessary waste of resources.

Implement file lifetime management for the fops_bool file_operations.
Namely, make debugfs_read_file_bool() and debugfs_write_file_bool() safe
against file removals by means of debugfs_use_file_start() and
debugfs_use_file_finish().

Make debugfs_create_bool() create its files in non-proxying operation mode
through debugfs_create_mode_unsafe().

Finally, purge debugfs_create_mode() as debugfs_create_bool() had been its
last user.

Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Nicolai Stange 2016-03-22 14:11:18 +01:00 committed by Greg Kroah-Hartman
parent 4909f16810
commit 4d45f7974c
1 changed files with 20 additions and 21 deletions
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39
fs/debugfs/file.c
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@ -312,22 +312,6 @@ ssize_t debugfs_attr_write(struct file *file, const char __user *buf,
}
EXPORT_SYMBOL_GPL(debugfs_attr_write);
static struct dentry *debugfs_create_mode(const char *name, umode_t mode,
struct dentry *parent, void *value,
const struct file_operations *fops,
const struct file_operations *fops_ro,
const struct file_operations *fops_wo)
{
/* if there are no write bits set, make read only */
if (!(mode & S_IWUGO))
return debugfs_create_file(name, mode, parent, value, fops_ro);
/* if there are no read bits set, make write only */
if (!(mode & S_IRUGO))
return debugfs_create_file(name, mode, parent, value, fops_wo);
return debugfs_create_file(name, mode, parent, value, fops);
}
static struct dentry *debugfs_create_mode_unsafe(const char *name, umode_t mode,
struct dentry *parent, void *value,
const struct file_operations *fops,
@ -756,9 +740,17 @@ ssize_t debugfs_read_file_bool(struct file *file, char __user *user_buf,
size_t count, loff_t *ppos)
{
char buf[3];
bool *val = file->private_data;
bool val;
int r, srcu_idx;
if (*val)
r = debugfs_use_file_start(F_DENTRY(file), &srcu_idx);
if (likely(!r))
val = *(bool *)file->private_data;
debugfs_use_file_finish(srcu_idx);
if (r)
return r;
if (val)
buf[0] = 'Y';
else
buf[0] = 'N';
@ -774,6 +766,7 @@ ssize_t debugfs_write_file_bool(struct file *file, const char __user *user_buf,
char buf[32];
size_t buf_size;
bool bv;
int r, srcu_idx;
bool *val = file->private_data;
buf_size = min(count, (sizeof(buf)-1));
@ -781,8 +774,14 @@ ssize_t debugfs_write_file_bool(struct file *file, const char __user *user_buf,
return -EFAULT;
buf[buf_size] = '\0';
if (strtobool(buf, &bv) == 0)
if (strtobool(buf, &bv) == 0) {
r = debugfs_use_file_start(F_DENTRY(file), &srcu_idx);
if (likely(!r))
*val = bv;
debugfs_use_file_finish(srcu_idx);
if (r)
return r;
}
return count;
}
@ -834,7 +833,7 @@ static const struct file_operations fops_bool_wo = {
struct dentry *debugfs_create_bool(const char *name, umode_t mode,
struct dentry *parent, bool *value)
{
return debugfs_create_mode(name, mode, parent, value, &fops_bool,
return debugfs_create_mode_unsafe(name, mode, parent, value, &fops_bool,
&fops_bool_ro, &fops_bool_wo);
}
EXPORT_SYMBOL_GPL(debugfs_create_bool);