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>

4 files changed, 4 insertions, 17 deletions

diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index 60a359b35582..db7fa5cab988 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;     
 }
 
@@ -504,6 +499,7 @@ int proc_readdir(struct file *filp, void *dirent, filldir_t filldir)
  * the /proc directory.
  */
 static const struct file_operations proc_dir_operations = {
+        .llseek                 = generic_file_llseek,
         .read                   = generic_read_dir,
         .readdir                = proc_readdir,
 };
diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index 2543fd00c658..3e76bb9b3ad6 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 7bc296f424ae..04d1270f1c38 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>
@@ -172,6 +171,7 @@ static int proc_tgid_net_readdir(struct file *filp, void *dirent,
 }
 
 const struct file_operations proc_net_operations = {
+        .llseek         = generic_file_llseek,
         .read           = generic_read_dir,
         .readdir        = proc_tgid_net_readdir,
 };
diff --git a/fs/proc/root.c b/fs/proc/root.c
index 7761602af9de..f6299a25594e 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;