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, 4 insertions, 3 deletions

diff --git a/net/wanrouter/wanmain.c b/net/wanrouter/wanmain.c
index 258daa8..2bf2340 100644
--- a/net/wanrouter/wanmain.c
+++ b/net/wanrouter/wanmain.c
@@ -48,7 +48,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>	/* support for loadable modules */
 #include <linux/slab.h>		/* kmalloc(), kfree() */
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
 #include <linux/mm.h>
 #include <linux/string.h>	/* inline mem*, str* functions */
 
@@ -71,6 +71,7 @@
  *	WAN device IOCTL handlers
  */
 
+static DEFINE_MUTEX(wanrouter_mutex);
 static int wanrouter_device_setup(struct wan_device *wandev,
 				  wandev_conf_t __user *u_conf);
 static int wanrouter_device_stat(struct wan_device *wandev,
@@ -376,7 +377,7 @@ long wanrouter_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	if (wandev->magic != ROUTER_MAGIC)
 		return -EINVAL;
 
-	lock_kernel();
+	mutex_lock(&wanrouter_mutex);
 	switch (cmd) {
 	case ROUTER_SETUP:
 		err = wanrouter_device_setup(wandev, data);
@@ -408,7 +409,7 @@ long wanrouter_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 			err = wandev->ioctl(wandev, cmd, arg);
 		else err = -EINVAL;
 	}
-	unlock_kernel();
+	mutex_unlock(&wanrouter_mutex);
 	return err;
 }