From: Arnd Bergmann <a...@arndb.de>
The slp_s0_residency_usec debugfs file currently uses
DEFINE_DEBUGFS_ATTRIBUTE(), but that macro cannot really be used to
define files outside of the debugfs code, as it has no reference to
the get/set functions if CONFIG_DEBUG_FS is not defined:
drivers/platform/x86/intel_pmc_core.c:80:12: error: ‘pmc_core_dev_state_get’
defined but not used [-Werror=unused-function]
This fixes the macro to always contain the reference, and instead rely
on the stubbed-out debugfs_create_file to not actually refer to
its arguments so the compiler can still drop the reference.
This works because the attribute definition is always 'static',
and the dead-code removal silently drops all static symbols
that are not used.
Fixes: c64688081490 ("debugfs: add support for self-protecting attribute file
fops")
Fixes: df2294fb6428 ("intel_pmc_core: Convert to DEFINE_DEBUGFS_ATTRIBUTE")
Signed-off-by: Arnd Bergmann <a...@arndb.de>
[nicsta...@gmail.com: Add dummy implementations of debugfs_attr_read() and
debugfs_attr_write() in order to protect against possibly broken dead
code elimination and to improve readability.
Correct CONFIG_DEBUGFS_FS -> CONFIG_DEBUG_FS typo in changelog.]
Signed-off-by: Nicolai Stange <nicsta...@gmail.com>
---
Compile-tested on top of next-20161020 with gcc-4.9.0 and gcc-6.2.1,
CONFIG_INTEL_PMC_CORE=y and both, CONFIG_DEBUG_FS=n and CONFIG_DEBUG_FS=y.
I verified that there isn't anything in the intel_pmc_core.o that shouldn'tbe
there with CONFIG_DEBUG_FS=n.
Changes to v1:
- Add dummy implementations of debugfs_attr_read()/debugfs_attr_write()
for the CONFIG_DEBUG_FS=n case.
- Fix a typo in the changelog.
include/linux/debugfs.h | 44 +++++++++++++++++++++++++++-----------------
1 file changed, 27 insertions(+), 17 deletions(-)
diff --git a/include/linux/debugfs.h b/include/linux/debugfs.h
index 4d3f0d1..1b413a9 100644
--- a/include/linux/debugfs.h
+++ b/include/linux/debugfs.h
@@ -62,6 +62,21 @@ static inline const struct file_operations
*debugfs_real_fops(struct file *filp)
return filp->f_path.dentry->d_fsdata;
}
+#define DEFINE_DEBUGFS_ATTRIBUTE(__fops, __get, __set, __fmt) \
+static int __fops ## _open(struct inode *inode, struct file *file) \
+{ \
+ __simple_attr_check_format(__fmt, 0ull); \
+ return simple_attr_open(inode, file, __get, __set, __fmt); \
+} \
+static const struct file_operations __fops = { \
+ .owner = THIS_MODULE, \
+ .open = __fops ## _open, \
+ .release = simple_attr_release, \
+ .read = debugfs_attr_read, \
+ .write = debugfs_attr_write, \
+ .llseek = generic_file_llseek, \
+}
+
#if defined(CONFIG_DEBUG_FS)
struct dentry *debugfs_create_file(const char *name, umode_t mode,
@@ -99,21 +114,6 @@ ssize_t debugfs_attr_read(struct file *file, char __user
*buf,
ssize_t debugfs_attr_write(struct file *file, const char __user *buf,
size_t len, loff_t *ppos);
-#define DEFINE_DEBUGFS_ATTRIBUTE(__fops, __get, __set, __fmt) \
-static int __fops ## _open(struct inode *inode, struct file *file) \
-{ \
- __simple_attr_check_format(__fmt, 0ull); \
- return simple_attr_open(inode, file, __get, __set, __fmt); \
-} \
-static const struct file_operations __fops = { \
- .owner = THIS_MODULE, \
- .open = __fops ## _open, \
- .release = simple_attr_release, \
- .read = debugfs_attr_read, \
- .write = debugfs_attr_write, \
- .llseek = generic_file_llseek, \
-}
-
struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry
*old_dentry,
struct dentry *new_dir, const char *new_name);
@@ -233,8 +233,18 @@ static inline void debugfs_use_file_finish(int srcu_idx)
__releases(&debugfs_srcu)
{ }
-#define DEFINE_DEBUGFS_ATTRIBUTE(__fops, __get, __set, __fmt) \
- static const struct file_operations __fops = { 0 }
+static inline ssize_t debugfs_attr_read(struct file *file, char __user *buf,
+ size_t len, loff_t *ppos)
+{
+ return -ENODEV;
+}
+
+static inline ssize_t debugfs_attr_write(struct file *file,
+ const char __user *buf,
+ size_t len, loff_t *ppos)
+{
+ return -ENODEV;
+}
static inline struct dentry *debugfs_rename(struct dentry *old_dir, struct
dentry *old_dentry,
struct dentry *new_dir, char *new_name)
--
2.10.1
