The patch titled
Subject: proc: faster /proc/$PID lookup
has been added to the -mm tree. Its filename is
proc-faster-proc-pid-lookup.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/proc-faster-proc-pid-lookup.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/proc-faster-proc-pid-lookup.patch
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------------------------------------------------------
From: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Subject: proc: faster /proc/$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 <adobriyan@xxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/base.c | 2 +-
fs/proc/root.c | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)
diff -puN fs/proc/base.c~proc-faster-proc-pid-lookup fs/proc/base.c
--- a/fs/proc/base.c~proc-faster-proc-pid-lookup
+++ a/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 -puN fs/proc/root.c~proc-faster-proc-pid-lookup fs/proc/root.c
--- a/fs/proc/root.c~proc-faster-proc-pid-lookup
+++ a/fs/proc/root.c
@@ -199,10 +199,10 @@ static int proc_root_getattr(struct vfsm
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)
_
Patches currently in -mm which might be from adobriyan@xxxxxxxxx are
lib-test-kstrtoxc-use-array_size-instead-of-sizeof-sizeof.patch
proc-add-and-remove-proc-entry-create-checks.patch
proc-faster-proc-pid-lookup.patch
proc-make-proc_subdir_lock-static.patch
proc-remove-proc_tty_ldisc-variable.patch
proc-remove-proc_tty_ldisc-variable-fix.patch
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