procfs: reorder struct pid_dentry to save space on 64bit archs, and constify them

Change the order of fields of struct pid_entry (file fs/proc/base.c) in order
to avoid a hole on 64bit archs.  (8 bytes saved per object)

Also change all pid_entry arrays to be const qualified, to make clear they
must not be modified.

Before (on x86_64) :

# size fs/proc/base.o
   text    data     bss     dec     hex filename
  15549    2192       0   17741    454d fs/proc/base.o

After :

# size fs/proc/base.o
   text    data     bss     dec     hex filename
  17229     176       0   17405    43fd fs/proc/base.o

Thats 336 bytes saved on kernel size on x86_64

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 17f7a7ee6c5e14aa00e2b9b8a999a8cfa89d21d9..be94ddebb413273309b9c111986b2ec8979daeae 100644 (file)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -91,8 +91,8 @@
 #define PROC_NUMBUF 13
 
 struct pid_entry {
-       int len;
        char *name;
+       int len;
        mode_t mode;
        const struct inode_operations *iop;
        const struct file_operations *fop;
@@ -100,8 +100,8 @@ struct pid_entry {
 };
 
 #define NOD(NAME, MODE, IOP, FOP, OP) {                        \
-       .len  = sizeof(NAME) - 1,                       \
        .name = (NAME),                                 \
+       .len  = sizeof(NAME) - 1,                       \
        .mode = MODE,                                   \
        .iop  = IOP,                                    \
        .fop  = FOP,                                    \
@@ -1159,7 +1159,8 @@ static struct dentry_operations pid_dentry_operations =
 
 /* Lookups */
 
-typedef struct dentry *instantiate_t(struct inode *, struct dentry *, struct task_struct *, void *);
+typedef struct dentry *instantiate_t(struct inode *, struct dentry *,
+                               struct task_struct *, const void *);
 
 /*
  * Fill a directory entry.
@@ -1175,7 +1176,7 @@ typedef struct dentry *instantiate_t(struct inode *, struct dentry *, struct tas
  */
 static int proc_fill_cache(struct file *filp, void *dirent, filldir_t filldir,
        char *name, int len,
-       instantiate_t instantiate, struct task_struct *task, void *ptr)
+       instantiate_t instantiate, struct task_struct *task, const void *ptr)
 {
        struct dentry *child, *dir = filp->f_path.dentry;
        struct inode *inode;
@@ -1310,9 +1311,9 @@ static struct dentry_operations tid_fd_dentry_operations =
 };
 
 static struct dentry *proc_fd_instantiate(struct inode *dir,
-       struct dentry *dentry, struct task_struct *task, void *ptr)
+       struct dentry *dentry, struct task_struct *task, const void *ptr)
 {
-       unsigned fd = *(unsigned *)ptr;
+       unsigned fd = *(const unsigned *)ptr;
        struct file *file;
        struct files_struct *files;
        struct inode *inode;
@@ -1478,9 +1479,9 @@ static const struct inode_operations proc_fd_inode_operations = {
 };
 
 static struct dentry *proc_pident_instantiate(struct inode *dir,
-       struct dentry *dentry, struct task_struct *task, void *ptr)
+       struct dentry *dentry, struct task_struct *task, const void *ptr)
 {
-       struct pid_entry *p = ptr;
+       const struct pid_entry *p = ptr;
        struct inode *inode;
        struct proc_inode *ei;
        struct dentry *error = ERR_PTR(-EINVAL);
@@ -1509,13 +1510,13 @@ out:
 
 static struct dentry *proc_pident_lookup(struct inode *dir, 
                                         struct dentry *dentry,
-                                        struct pid_entry *ents,
+                                        const struct pid_entry *ents,
                                         unsigned int nents)
 {
        struct inode *inode;
        struct dentry *error;
        struct task_struct *task = get_proc_task(dir);
-       struct pid_entry *p, *last;
+       const struct pid_entry *p, *last;
 
        error = ERR_PTR(-ENOENT);
        inode = NULL;
@@ -1544,8 +1545,8 @@ out_no_task:
        return error;
 }
 
-static int proc_pident_fill_cache(struct file *filp, void *dirent, filldir_t filldir,
-       struct task_struct *task, struct pid_entry *p)
+static int proc_pident_fill_cache(struct file *filp, void *dirent,
+       filldir_t filldir, struct task_struct *task, const struct pid_entry *p)
 {
        return proc_fill_cache(filp, dirent, filldir, p->name, p->len,
                                proc_pident_instantiate, task, p);
@@ -1553,14 +1554,14 @@ static int proc_pident_fill_cache(struct file *filp, void *dirent, filldir_t fil
 
 static int proc_pident_readdir(struct file *filp,
                void *dirent, filldir_t filldir,
-               struct pid_entry *ents, unsigned int nents)
+               const struct pid_entry *ents, unsigned int nents)
 {
        int i;
        int pid;
        struct dentry *dentry = filp->f_path.dentry;
        struct inode *inode = dentry->d_inode;
        struct task_struct *task = get_proc_task(inode);
-       struct pid_entry *p, *last;
+       const struct pid_entry *p, *last;
        ino_t ino;
        int ret;
 
@@ -1675,7 +1676,7 @@ static const struct file_operations proc_pid_attr_operations = {
        .write          = proc_pid_attr_write,
 };
 
-static struct pid_entry attr_dir_stuff[] = {
+static const struct pid_entry attr_dir_stuff[] = {
        REG("current",    S_IRUGO|S_IWUGO, pid_attr),
        REG("prev",       S_IRUGO,         pid_attr),
        REG("exec",       S_IRUGO|S_IWUGO, pid_attr),
@@ -1741,7 +1742,7 @@ static const struct inode_operations proc_self_inode_operations = {
  * that properly belong to the /proc filesystem, as they describe
  * describe something that is process related.
  */
-static struct pid_entry proc_base_stuff[] = {
+static const struct pid_entry proc_base_stuff[] = {
        NOD("self", S_IFLNK|S_IRWXUGO,
                &proc_self_inode_operations, NULL, {}),
 };
@@ -1770,9 +1771,9 @@ static struct dentry_operations proc_base_dentry_operations =
 };
 
 static struct dentry *proc_base_instantiate(struct inode *dir,
-       struct dentry *dentry, struct task_struct *task, void *ptr)
+       struct dentry *dentry, struct task_struct *task, const void *ptr)
 {
-       struct pid_entry *p = ptr;
+       const struct pid_entry *p = ptr;
        struct inode *inode;
        struct proc_inode *ei;
        struct dentry *error = ERR_PTR(-EINVAL);
@@ -1820,7 +1821,7 @@ static struct dentry *proc_base_lookup(struct inode *dir, struct dentry *dentry)
 {
        struct dentry *error;
        struct task_struct *task = get_proc_task(dir);
-       struct pid_entry *p, *last;
+       const struct pid_entry *p, *last;
 
        error = ERR_PTR(-ENOENT);
 
@@ -1846,8 +1847,8 @@ out_no_task:
        return error;
 }
 
-static int proc_base_fill_cache(struct file *filp, void *dirent, filldir_t filldir,
-       struct task_struct *task, struct pid_entry *p)
+static int proc_base_fill_cache(struct file *filp, void *dirent,
+       filldir_t filldir, struct task_struct *task, const struct pid_entry *p)
 {
        return proc_fill_cache(filp, dirent, filldir, p->name, p->len,
                                proc_base_instantiate, task, p);
@@ -1884,7 +1885,7 @@ static int proc_pid_io_accounting(struct task_struct *task, char *buffer)
 static const struct file_operations proc_task_operations;
 static const struct inode_operations proc_task_inode_operations;
 
-static struct pid_entry tgid_base_stuff[] = {
+static const struct pid_entry tgid_base_stuff[] = {
        DIR("task",       S_IRUGO|S_IXUGO, task),
        DIR("fd",         S_IRUSR|S_IXUSR, fd),
        INF("environ",    S_IRUSR, pid_environ),
@@ -2027,7 +2028,7 @@ out:
 
 static struct dentry *proc_pid_instantiate(struct inode *dir,
                                           struct dentry * dentry,
-                                          struct task_struct *task, void *ptr)
+                                          struct task_struct *task, const void *ptr)
 {
        struct dentry *error = ERR_PTR(-ENOENT);
        struct inode *inode;
@@ -2142,7 +2143,7 @@ int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir)
                goto out_no_task;
 
        for (; nr < ARRAY_SIZE(proc_base_stuff); filp->f_pos++, nr++) {
-               struct pid_entry *p = &proc_base_stuff[nr];
+               const struct pid_entry *p = &proc_base_stuff[nr];
                if (proc_base_fill_cache(filp, dirent, filldir, reaper, p) < 0)
                        goto out;
        }
@@ -2168,7 +2169,7 @@ out_no_task:
 /*
  * Tasks
  */
-static struct pid_entry tid_base_stuff[] = {
+static const struct pid_entry tid_base_stuff[] = {
        DIR("fd",        S_IRUSR|S_IXUSR, fd),
        INF("environ",   S_IRUSR, pid_environ),
        INF("auxv",      S_IRUSR, pid_auxv),
@@ -2238,7 +2239,7 @@ static const struct inode_operations proc_tid_base_inode_operations = {
 };
 
 static struct dentry *proc_task_instantiate(struct inode *dir,
-       struct dentry *dentry, struct task_struct *task, void *ptr)
+       struct dentry *dentry, struct task_struct *task, const void *ptr)
 {
        struct dentry *error = ERR_PTR(-ENOENT);
        struct inode *inode;