isdn: 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: Karsten Keil <isdn@linux-pingi.de>
Cc: netdev@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 3 deletions

diff --git a/drivers/isdn/divert/divert_procfs.c b/drivers/isdn/divert/divert_procfs.c
index c53e2417e7d4..33ec9e467772 100644
--- a/drivers/isdn/divert/divert_procfs.c
+++ b/drivers/isdn/divert/divert_procfs.c
@@ -20,7 +20,7 @@
 #include <linux/sched.h>
 #include <linux/isdnif.h>
 #include <net/net_namespace.h>
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
 #include "isdn_divert.h"
 
 
@@ -28,6 +28,7 @@
 /* Variables for interface queue */
 /*********************************/
 ulong if_used = 0;		/* number of interface users */
+static DEFINE_MUTEX(isdn_divert_mutex);
 static struct divert_info *divert_info_head = NULL;	/* head of queue */
 static struct divert_info *divert_info_tail = NULL;	/* pointer to last entry */
 static DEFINE_SPINLOCK(divert_info_lock);/* lock for queue */
@@ -261,9 +262,9 @@ static long isdn_divert_ioctl(struct file *file, uint cmd, ulong arg)
 {
 	long ret;
 
-	lock_kernel();
+	mutex_lock(&isdn_divert_mutex);
 	ret = isdn_divert_ioctl_unlocked(file, cmd, arg);
-	unlock_kernel();
+	mutex_unlock(&isdn_divert_mutex);
 
 	return ret;
 }