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Subject[PATCH] proc: stop using BKL
[added to proc.git]

commit e137447fbf30784a86b79707ef0d76de8c6bcf8d
Author: Alexey Dobriyan <adobriyan@gmail.com>
Date: Fri Oct 24 15:30:36 2008 +0400

proc: stop using BKL

There are four BKL users in proc: de_put(), proc_lookup_de(),
proc_readdir_de(), proc_root_readdir(),

1) de_put()
-----------
de_put() is classic atomic_dec_and_test() refcount wrapper -- no BKL
needed. BKL doesn't matter to possible refcount leak as well.
2) proc_lookup_de()
-------------------
Walking PDE list is protected by proc_subdir_lock(), proc_get_inode() is
potentially blocking, all callers of proc_lookup_de() eventually end up
from ->lookup hooks which is protected by directory's ->i_mutex -- BKL
doesn't protect anything.
3) proc_readdir_de()
--------------------
"." and ".." part doesn't need BKL, walking PDE list is under
proc_subdir_lock, calling filldir callback is potentially blocking
because it writes to luserspace. All proc_readdir_de() callers
eventually come from ->readdir hook which is under directory's
->i_mutex -- BKL doesn't protect anything.
4) proc_root_readdir_de()
-------------------------
proc_root_readdir_de is ->readdir hook, see (3).
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>

diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index 60a359b..988a807 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -14,7 +14,6 @@
#include <linux/stat.h>
#include <linux/module.h>
#include <linux/mount.h>
-#include <linux/smp_lock.h>
#include <linux/init.h>
#include <linux/idr.h>
#include <linux/namei.h>
@@ -379,7 +378,6 @@ struct dentry *proc_lookup_de(struct proc_dir_entry *de, struct inode *dir,
struct inode *inode = NULL;
int error = -ENOENT;

- lock_kernel();
spin_lock(&proc_subdir_lock);
for (de = de->subdir; de ; de = de->next) {
if (de->namelen != dentry->d_name.len)
@@ -397,7 +395,6 @@ struct dentry *proc_lookup_de(struct proc_dir_entry *de, struct inode *dir,
}
spin_unlock(&proc_subdir_lock);
out_unlock:
- unlock_kernel();

if (inode) {
dentry->d_op = &proc_dentry_operations;
@@ -432,8 +429,6 @@ int proc_readdir_de(struct proc_dir_entry *de, struct file *filp, void *dirent,
struct inode *inode = filp->f_path.dentry->d_inode;
int ret = 0;

- lock_kernel();
-
ino = inode->i_ino;
i = filp->f_pos;
switch (i) {
@@ -487,7 +482,7 @@ int proc_readdir_de(struct proc_dir_entry *de, struct file *filp, void *dirent,
spin_unlock(&proc_subdir_lock);
}
ret = 1;
-out: unlock_kernel();
+out:
return ret;
}

diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index 2543fd0..3e76bb9 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -35,16 +35,13 @@ struct proc_dir_entry *de_get(struct proc_dir_entry *de)
*/
void de_put(struct proc_dir_entry *de)
{
- lock_kernel();
if (!atomic_read(&de->count)) {
printk("de_put: entry %s already free!\n", de->name);
- unlock_kernel();
return;
}

if (atomic_dec_and_test(&de->count))
free_proc_entry(de);
- unlock_kernel();
}

/*
diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c
index 7bc296f..a7bd61e 100644
--- a/fs/proc/proc_net.c
+++ b/fs/proc/proc_net.c
@@ -18,7 +18,6 @@
#include <linux/sched.h>
#include <linux/module.h>
#include <linux/bitops.h>
-#include <linux/smp_lock.h>
#include <linux/mount.h>
#include <linux/nsproxy.h>
#include <net/net_namespace.h>
diff --git a/fs/proc/root.c b/fs/proc/root.c
index 7761602..f6299a2 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -16,7 +16,6 @@
#include <linux/sched.h>
#include <linux/module.h>
#include <linux/bitops.h>
-#include <linux/smp_lock.h>
#include <linux/mount.h>
#include <linux/pid_namespace.h>

@@ -162,17 +161,12 @@ static int proc_root_readdir(struct file * filp,
unsigned int nr = filp->f_pos;
int ret;

- lock_kernel();
-
if (nr < FIRST_PROCESS_ENTRY) {
int error = proc_readdir(filp, dirent, filldir);
- if (error <= 0) {
- unlock_kernel();
+ if (error <= 0)
return error;
- }
filp->f_pos = FIRST_PROCESS_ENTRY;
}
- unlock_kernel();

ret = proc_pid_readdir(filp, dirent, filldir);
return ret;

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