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SubjectRe: simplify procfs code for seq_file instances V2
On Sun, May 06, 2018 at 08:19:49PM +0300, Alexey Dobriyan wrote:
> +++ b/fs/proc/internal.h
> @@ -48,8 +48,8 @@ struct proc_dir_entry {
> const struct seq_operations *seq_ops;
> int (*single_show)(struct seq_file *, void *);
> };
> - unsigned int state_size;
> void *data;
> + unsigned int state_size;
> unsigned int low_ino;
> nlink_t nlink;
> kuid_t uid;

Makes sense

> @@ -62,9 +62,9 @@ struct proc_dir_entry {
> umode_t mode;
> u8 namelen;
> #ifdef CONFIG_64BIT
> -#define SIZEOF_PDE_INLINE_NAME (192-139)
> +#define SIZEOF_PDE_INLINE_NAME (192-155)
> #else
> -#define SIZEOF_PDE_INLINE_NAME (128-87)
> +#define SIZEOF_PDE_INLINE_NAME (128-95)

> #endif
> char inline_name[SIZEOF_PDE_INLINE_NAME];
> } __randomize_layout;

*UGH*

Both to the original state and that kind of "adjustments".
Incidentally, with __bugger_layout in there these expressions
are simply wrong.

If nothing else, I would suggest turning the last one into
char inline_name[];
in hope that layout won't get... randomized that much and
used

#ifdef CONFIG_64BIT
#define PDE_SIZE 192
#else
#define PDE_SIZE 128
#endif

union __proc_dir_entry {
char pad[PDE_SIZE];
struct proc_dir_entry real;
};

#define SIZEOF_PDE_INLINE_NAME (PDE_SIZE - offsetof(struct proc_dir_entry, inline_name))

for constants, adjusted sizeof and sizeof_field when creating
proc_dir_entry_cache and turned proc_root into

union __proc_dir_entry __proc_root = { .real = {
.low_ino = PROC_ROOT_INO,
.namelen = 5,
.mode = S_IFDIR | S_IRUGO | S_IXUGO,
.nlink = 2,
.refcnt = REFCOUNT_INIT(1),
.proc_iops = &proc_root_inode_operations,
.proc_fops = &proc_root_operations,
.parent = &__proc_root.real,
.subdir = RB_ROOT,
.name = __proc_root.real.inline_name,
.inline_name = "/proc",
}};

#define proc_root __proc_root.real
(or actually used __proc_root.real in all of a 6 places where it remains).

> diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c
> index baf1994289ce..7d94fa005b0d 100644
> --- a/fs/proc/proc_net.c
> +++ b/fs/proc/proc_net.c
> @@ -40,7 +40,7 @@ static struct net *get_proc_net(const struct inode *inode)
>
> static int seq_open_net(struct inode *inode, struct file *file)
> {
> - size_t state_size = PDE(inode)->state_size;
> + unsigned int state_size = PDE(inode)->state_size;
> struct seq_net_private *p;
> struct net *net;

<shakes head>
You and your "size_t is evil" crusade...

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