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>

1 files changed, 5 insertions, 5 deletions

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;
 }