From 335eb53158466a4c4d018fa53ceb8c8ba1067fa3 Mon Sep 17 00:00:00 2001 From: Alexey Dobriyan Date: Fri, 8 Aug 2014 14:21:27 -0700 Subject: [PATCH] proc: faster /proc/$PID lookup Currently lookup for /proc/$PID first goes through spinlock and whole list of misc /proc entries only to confirm that, yes, /proc/42 can not possibly match random proc entry. List is is several dozens entries long (52 entries on my setup). None of this is necessary. Try to convert dentry name to integer first. If it works, it must be /proc/$PID. If it doesn't, it must be random proc entry. Based on patch from Al Viro. Signed-off-by: Alexey Dobriyan Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/base.c | 2 +- fs/proc/root.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/fs/proc/base.c b/fs/proc/base.c index 11375216b49..35afb2eb4a6 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -2780,7 +2780,7 @@ out: struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, unsigned int flags) { - int result = 0; + int result = -ENOENT; struct task_struct *task; unsigned tgid; struct pid_namespace *ns; diff --git a/fs/proc/root.c b/fs/proc/root.c index 5dbadecb234..574bafc41f0 100644 --- a/fs/proc/root.c +++ b/fs/proc/root.c @@ -199,10 +199,10 @@ static int proc_root_getattr(struct vfsmount *mnt, struct dentry *dentry, struct static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags) { - if (!proc_lookup(dir, dentry, flags)) + if (!proc_pid_lookup(dir, dentry, flags)) return NULL; - return proc_pid_lookup(dir, dentry, flags); + return proc_lookup(dir, dentry, flags); } static int proc_root_readdir(struct file *file, struct dir_context *ctx) -- 2.46.0