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, 6 insertions, 6 deletions

diff --git a/drivers/char/nwflash.c b/drivers/char/nwflash.c
index 043a1c7b86be..a12f52400dbc 100644
--- a/drivers/char/nwflash.c
+++ b/drivers/char/nwflash.c
@@ -25,7 +25,6 @@
 #include <linux/spinlock.h>
 #include <linux/rwsem.h>
 #include <linux/init.h>
-#include <linux/smp_lock.h>
 #include <linux/mutex.h>
 #include <linux/jiffies.h>
 
@@ -41,6 +40,7 @@
 
 #define	NWFLASH_VERSION "6.4"
 
+static DEFINE_MUTEX(flash_mutex);
 static void kick_open(void);
 static int get_flash_id(void);
 static int erase_block(int nBlock);
@@ -96,7 +96,7 @@ static int get_flash_id(void)
 
 static long flash_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
 {
-	lock_kernel();
+	mutex_lock(&flash_mutex);
 	switch (cmd) {
 	case CMD_WRITE_DISABLE:
 		gbWriteBase64Enable = 0;
@@ -114,10 +114,10 @@ static long flash_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
 	default:
 		gbWriteBase64Enable = 0;
 		gbWriteEnable = 0;
-		unlock_kernel();
+		mutex_unlock(&flash_mutex);
 		return -EINVAL;
 	}
-	unlock_kernel();
+	mutex_unlock(&flash_mutex);
 	return 0;
 }
 
@@ -282,7 +282,7 @@ static loff_t flash_llseek(struct file *file, loff_t offset, int orig)
 {
 	loff_t ret;
 
-	lock_kernel();
+	mutex_lock(&flash_mutex);
 	if (flashdebug)
 		printk(KERN_DEBUG "flash_llseek: offset=0x%X, orig=0x%X.\n",
 		       (unsigned int) offset, orig);
@@ -317,7 +317,7 @@ static loff_t flash_llseek(struct file *file, loff_t offset, int orig)
 	default:
 		ret = -EINVAL;
 	}
-	unlock_kernel();
+	mutex_unlock(&flash_mutex);
 	return ret;
 }