drivers: 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.

These drivers do not seem to be under active
maintainance from my brief investigation. Apologies
to those maintainers that I have missed.

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>

1 files changed, 5 insertions, 4 deletions

diff --git a/drivers/char/toshiba.c b/drivers/char/toshiba.c
index f8bc79f6de34..f8f09ab0b170 100644
--- a/drivers/char/toshiba.c
+++ b/drivers/char/toshiba.c
@@ -68,7 +68,7 @@
 #include <linux/stat.h>
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
 #include <linux/toshiba.h>
 
 #define TOSH_MINOR_DEV 181
@@ -78,6 +78,7 @@ MODULE_AUTHOR("Jonathan Buzzard <jonathan@buzzard.org.uk>");
 MODULE_DESCRIPTION("Toshiba laptop SMM driver");
 MODULE_SUPPORTED_DEVICE("toshiba");
 
+static DEFINE_MUTEX(tosh_mutex);
 static int tosh_fn;
 module_param_named(fn, tosh_fn, int, 0);
 MODULE_PARM_DESC(fn, "User specified Fn key detection port");
@@ -274,16 +275,16 @@ static long tosh_ioctl(struct file *fp, unsigned int cmd, unsigned long arg)
 				return -EINVAL;
 
 			/* do we need to emulate the fan ? */
-			lock_kernel();
+			mutex_lock(&tosh_mutex);
 			if (tosh_fan==1) {
 				if (((ax==0xf300) || (ax==0xf400)) && (bx==0x0004)) {
 					err = tosh_emulate_fan(&regs);
-					unlock_kernel();
+					mutex_unlock(&tosh_mutex);
 					break;
 				}
 			}
 			err = tosh_smm(&regs);
-			unlock_kernel();
+			mutex_unlock(&tosh_mutex);
 			break;
 		default:
 			return -EINVAL;