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

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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>
This commit is contained in:
David Howells 2011-07-27 21:47:03 +03:00 committed by Linus Torvalds
parent 5fd00b0315
commit 09570f9149
4 changed files with 7 additions and 8 deletions
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3
fs/proc/generic.c
View file

@ -620,8 +620,7 @@ static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent,
if (!ent) goto out;
memset(ent, 0, sizeof(struct proc_dir_entry));
memcpy(((char *) ent) + sizeof(struct proc_dir_entry), fn, len + 1);
ent->name = ((char *) ent) + sizeof(*ent);
memcpy(ent->name, fn, len + 1);
ent->namelen = len;
ent->mode = mode;
ent->nlink = nlink;

4
fs/proc/proc_net.c
View file

@ -197,15 +197,15 @@ static __net_init int proc_net_ns_init(struct net *net)
int err;
err = -ENOMEM;
netd = kzalloc(sizeof(*netd), GFP_KERNEL);
netd = kzalloc(sizeof(*netd) + 4, GFP_KERNEL);
if (!netd)
goto out;
netd->data = net;
netd->nlink = 2;
netd->name = "net";
netd->namelen = 3;
netd->parent = &proc_root;
memcpy(netd->name, "net", 4);
err = -EEXIST;
net_statd = proc_net_mkdir(net, "stat", netd);

2
fs/proc/root.c
View file

@ -186,13 +186,13 @@ static const struct inode_operations proc_root_inode_operations = {
struct proc_dir_entry proc_root = {
.low_ino = PROC_ROOT_INO,
.namelen = 5,
.name = "/proc",
.mode = S_IFDIR | S_IRUGO | S_IXUGO,
.nlink = 2,
.count = ATOMIC_INIT(1),
.proc_iops = &proc_root_inode_operations,
.proc_fops = &proc_root_operations,
.parent = &proc_root,
.name = "/proc",
};
int pid_ns_prepare_proc(struct pid_namespace *ns)

6
include/linux/proc_fs.h
View file

@ -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 {