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).
Since readdir hooks doesn't use BKL anymore, switch to
generic_file_llseek, since it also takes directory's i_mutex.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index 60a359b..db7fa5c 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 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 @@
}
spin_unlock(&proc_subdir_lock);
out_unlock:
- unlock_kernel();
if (inode) {
dentry->d_op = &proc_dentry_operations;
@@ -432,8 +429,6 @@
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 @@
spin_unlock(&proc_subdir_lock);
}
ret = 1;
-out: unlock_kernel();
+out:
return ret;
}
@@ -504,6 +499,7 @@
* the /proc directory.
*/
static const struct file_operations proc_dir_operations = {
+ .llseek = generic_file_llseek,
.read = generic_read_dir,
.readdir = proc_readdir,
};
