proc: make struct proc_dir_entry::name a terminal array rather than a pointer

Since __proc_create() appends the name it is given to the end of the PDE
structure that it allocates, there isn't a need to store a name pointer.
Instead we can just replace the name pointer with a terminal char array of
_unspecified_ length.  The compiler will simply append the string to statically
defined variables of PDE type overlapping any hole at the end of the structure
and, unlike specifying an explicitly _zero_ length array, won't give a warning
if you try to statically initialise it with a string of more than zero length.

Also, whilst we're at it:

 (1) Move namelen to end just prior to name and reduce it to a single byte
     (name shouldn't be longer than NAME_MAX).

 (2) Move pde_unload_lock two places further on so that if it's four bytes in
     size on a 64-bit machine, it won't cause an unused hole in the PDE struct.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index 650af6d..643b96c 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -50,8 +50,6 @@ typedef	int (write_proc_t)(struct file *file, const char __user *buffer,
 
 struct proc_dir_entry {
 	unsigned int low_ino;
-	unsigned int namelen;
-	const char *name;
 	mode_t mode;
 	nlink_t nlink;
 	uid_t uid;
@@ -73,9 +71,11 @@ struct proc_dir_entry {
 	write_proc_t *write_proc;
 	atomic_t count;		/* use count */
 	int pde_users;	/* number of callers into module in progress */
-	spinlock_t pde_unload_lock; /* proc_fops checks and pde_users bumps */
 	struct completion *pde_unload_completion;
 	struct list_head pde_openers;	/* who did ->open, but not ->release */
+	spinlock_t pde_unload_lock; /* proc_fops checks and pde_users bumps */
+	u8 namelen;
+	char name[];
 };
 
 enum kcore_type {