net: autoconvert trivial BKL users to private mutex

All these files use the big kernel lock in a trivial
way to serialize their private file operations,
typically resulting from an earlier semi-automatic
pushdown from VFS.

None of these drivers appears to want to lock against
other code, and they all use the BKL as the top-level
lock in their file operations, meaning that there
is no lock-order inversion problem.

Consequently, we can remove the BKL completely,
replacing it with a per-file mutex in every case.
Using a scripted approach means we can avoid
typos.

file=$1
name=$2
if grep -q lock_kernel ${file} ; then
    if grep -q 'include.*linux.mutex.h' ${file} ; then
            sed -i '/include.*<linux\/smp_lock.h>/d' ${file}
    else
            sed -i 's/include.*<linux\/smp_lock.h>.*$/include <linux\/mutex.h>/g' ${file}
    fi
    sed -i ${file} \
        -e "/^#include.*linux.mutex.h/,$ {
                1,/^\(static\|int\|long\)/ {
                     /^\(static\|int\|long\)/istatic DEFINE_MUTEX(${name}_mutex);

} }"  \
    -e "s/\(un\)*lock_kernel\>[ ]*()/mutex_\1lock(\&${name}_mutex)/g" \
    -e '/[      ]*cycle_kernel_lock();/d'
else
    sed -i -e '/include.*\<smp_lock.h\>/d' ${file}  \
                -e '/cycle_kernel_lock()/d'
fi

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: netdev@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 14 insertions, 15 deletions

diff --git a/drivers/net/ppp_generic.c b/drivers/net/ppp_generic.c
index e7b4187da057..6695a51e09e9 100644
--- a/drivers/net/ppp_generic.c
+++ b/drivers/net/ppp_generic.c
@@ -40,7 +40,6 @@
 #include <linux/if_arp.h>
 #include <linux/ip.h>
 #include <linux/tcp.h>
-#include <linux/smp_lock.h>
 #include <linux/spinlock.h>
 #include <linux/rwsem.h>
 #include <linux/stddef.h>
@@ -180,6 +179,7 @@ struct channel {
  * channel.downl.
  */
 
+static DEFINE_MUTEX(ppp_mutex);
 static atomic_t ppp_unit_count = ATOMIC_INIT(0);
 static atomic_t channel_count = ATOMIC_INIT(0);
 
@@ -362,7 +362,6 @@ static const int npindex_to_ethertype[NUM_NP] = {
  */
 static int ppp_open(struct inode *inode, struct file *file)
 {
-        cycle_kernel_lock();
         /*
          * This could (should?) be enforced by the permissions on /dev/ppp.
          */
@@ -582,7 +581,7 @@ static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
                  * this fd and reopening /dev/ppp.
                  */
                 err = -EINVAL;
-                lock_kernel();
+                mutex_lock(&ppp_mutex);
                 if (pf->kind == INTERFACE) {
                         ppp = PF_TO_PPP(pf);
                         if (file == ppp->owner)
@@ -594,7 +593,7 @@ static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
                 } else
                         printk(KERN_DEBUG "PPPIOCDETACH file->f_count=%ld\n",
                                atomic_long_read(&file->f_count));
-                unlock_kernel();
+                mutex_unlock(&ppp_mutex);
                 return err;
         }
 
@@ -602,7 +601,7 @@ static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
                 struct channel *pch;
                 struct ppp_channel *chan;
 
-                lock_kernel();
+                mutex_lock(&ppp_mutex);
                 pch = PF_TO_CHANNEL(pf);
 
                 switch (cmd) {
@@ -624,7 +623,7 @@ static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
                                 err = chan->ops->ioctl(chan, cmd, arg);
                         up_read(&pch->chan_sem);
                 }
-                unlock_kernel();
+                mutex_unlock(&ppp_mutex);
                 return err;
         }
 
@@ -634,7 +633,7 @@ static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
                 return -EINVAL;
         }
 
-        lock_kernel();
+        mutex_lock(&ppp_mutex);
         ppp = PF_TO_PPP(pf);
         switch (cmd) {
         case PPPIOCSMRU:
@@ -782,7 +781,7 @@ static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
         default:
                 err = -ENOTTY;
         }
-        unlock_kernel();
+        mutex_unlock(&ppp_mutex);
         return err;
 }
 
@@ -795,7 +794,7 @@ static int ppp_unattached_ioctl(struct net *net, struct ppp_file *pf,
         struct ppp_net *pn;
         int __user *p = (int __user *)arg;
 
-        lock_kernel();
+        mutex_lock(&ppp_mutex);
         switch (cmd) {
         case PPPIOCNEWUNIT:
                 /* Create a new ppp unit */
@@ -846,7 +845,7 @@ static int ppp_unattached_ioctl(struct net *net, struct ppp_file *pf,
         default:
                 err = -ENOTTY;
         }
-        unlock_kernel();
+        mutex_unlock(&ppp_mutex);
         return err;
 }
 
diff --git a/drivers/net/wan/cosa.c b/drivers/net/wan/cosa.c
index f0bd70fb650c..04c6cd4333f1 100644
--- a/drivers/net/wan/cosa.c
+++ b/drivers/net/wan/cosa.c
@@ -89,7 +89,6 @@
 #include <linux/spinlock.h>
 #include <linux/mutex.h>
 #include <linux/device.h>
-#include <linux/smp_lock.h>
 #include <asm/io.h>
 #include <asm/dma.h>
 #include <asm/byteorder.h>
@@ -174,6 +173,7 @@ struct cosa_data {
  * Character device major number. 117 was allocated for us.
  * The value of 0 means to allocate a first free one.
  */
+static DEFINE_MUTEX(cosa_chardev_mutex);
 static int cosa_major = 117;
 
 /*
@@ -944,7 +944,7 @@ static int cosa_open(struct inode *inode, struct file *file)
         int n;
         int ret = 0;
 
-        lock_kernel();
+        mutex_lock(&cosa_chardev_mutex);
         if ((n=iminor(file->f_path.dentry->d_inode)>>CARD_MINOR_BITS)
                 >= nr_cards) {
                 ret = -ENODEV;
@@ -976,7 +976,7 @@ static int cosa_open(struct inode *inode, struct file *file)
         chan->rx_done = chrdev_rx_done;
         spin_unlock_irqrestore(&cosa->lock, flags);
 out:
-        unlock_kernel();
+        mutex_unlock(&cosa_chardev_mutex);
         return ret;
 }
 
@@ -1212,10 +1212,10 @@ static long cosa_chardev_ioctl(struct file *file, unsigned int cmd,
         struct cosa_data *cosa;
         long ret;
 
-        lock_kernel();
+        mutex_lock(&cosa_chardev_mutex);
         cosa = channel->cosa;
         ret = cosa_ioctl_common(cosa, channel, cmd, arg);
-        unlock_kernel();
+        mutex_unlock(&cosa_chardev_mutex);
         return ret;
 }