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| author | Alexey Dobriyan <adobriyan@gmail.com> | 2026-04-26 00:08:42 +0200 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2026-05-11 23:13:01 +0200 |
| commit | 912289ee831d92b377309dc832c0c3ce5906deae (patch) | |
| tree | a7735cd3e601351053fc10dc981f92b5737265a7 | |
| parent | 254f49634ee16a731174d2ae34bc50bd5f45e731 (diff) | |
| download | linux-stable-912289ee831d92b377309dc832c0c3ce5906deae.tar.gz linux-stable-912289ee831d92b377309dc832c0c3ce5906deae.zip | |
proc: allow to mark /proc files permanent outside of fs/proc/
Add proc_make_permanent() function to mark PDE as permanent to speed up
open/read/close (one alloc/free and lock/unlock less).
Enable it for built-in code and for compiled-in modules.
This function becomes nop magically in modular code.
Note, note, note!
If built-in code creates and deletes PDEs dynamically (not in init
hook), then proc_make_permanent() must not be used.
It is intended for simple code:
static int __init xxx_module_init(void)
{
g_pde = proc_create_single();
proc_make_permanent(g_pde);
return 0;
}
static void __exit xxx_module_exit(void)
{
remove_proc_entry(g_pde);
}
If module is built-in then exit hook never executed and PDE is
permanent so it is OK to mark it as such.
If module is module then rmmod will yank PDE, but proc_make_permanent()
is nop and core /proc code will do everything right.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Link: https://patch.msgid.link/20260425220844.1763933-2-mjguzik@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
| -rw-r--r-- | fs/proc/generic.c | 10 | ||||
| -rw-r--r-- | fs/proc/internal.h | 3 | ||||
| -rw-r--r-- | include/linux/proc_fs.h | 12 |
3 files changed, 25 insertions, 0 deletions
diff --git a/fs/proc/generic.c b/fs/proc/generic.c index 8bb81e58c9d8..c6ae076e1fa0 100644 --- a/fs/proc/generic.c +++ b/fs/proc/generic.c @@ -841,3 +841,13 @@ ssize_t proc_simple_write(struct file *f, const char __user *ubuf, size_t size, kfree(buf); return ret == 0 ? size : ret; } + +/* + * Not exported to modules: + * modules' /proc files aren't permanent because modules aren't permanent. + */ +void impl_proc_make_permanent(struct proc_dir_entry *pde) +{ + if (pde) + pde_make_permanent(pde); +} diff --git a/fs/proc/internal.h b/fs/proc/internal.h index 64dc44832808..1edbabbdbc5d 100644 --- a/fs/proc/internal.h +++ b/fs/proc/internal.h @@ -79,8 +79,11 @@ static inline bool pde_is_permanent(const struct proc_dir_entry *pde) return pde->flags & PROC_ENTRY_PERMANENT; } +/* This is for builtin code, not even for modules which are compiled in. */ static inline void pde_make_permanent(struct proc_dir_entry *pde) { + /* Ensure magic flag does something. */ + static_assert(PROC_ENTRY_PERMANENT != 0); pde->flags |= PROC_ENTRY_PERMANENT; } diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h index 19d1c5e5f335..d2860c18dca9 100644 --- a/include/linux/proc_fs.h +++ b/include/linux/proc_fs.h @@ -248,4 +248,16 @@ static inline struct pid_namespace *proc_pid_ns(struct super_block *sb) bool proc_ns_file(const struct file *file); +#if defined CONFIG_PROC_FS && !defined MODULE +void impl_proc_make_permanent(struct proc_dir_entry *pde); +#endif + +static inline void proc_make_permanent(struct proc_dir_entry *pde) +{ + /* Don't give matches to modules. */ +#if defined CONFIG_PROC_FS && !defined MODULE + impl_proc_make_permanent(pde); +#endif +} + #endif /* _LINUX_PROC_FS_H */ |