sbus: 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>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 7 deletions

diff --git a/drivers/sbus/char/flash.c b/drivers/sbus/char/flash.c
index 368d66294d8..ed9494e1885 100644
--- a/drivers/sbus/char/flash.c
+++ b/drivers/sbus/char/flash.c
@@ -10,7 +10,7 @@
 #include <linux/fcntl.h>
 #include <linux/poll.h>
 #include <linux/init.h>
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
 #include <linux/spinlock.h>
 #include <linux/mm.h>
 #include <linux/of.h>
@@ -22,6 +22,7 @@
 #include <asm/io.h>
 #include <asm/upa.h>
 
+static DEFINE_MUTEX(flash_mutex);
 static DEFINE_SPINLOCK(flash_lock);
 static struct {
 	unsigned long read_base;	/* Physical read address */
@@ -80,7 +81,7 @@ flash_mmap(struct file *file, struct vm_area_struct *vma)
 static long long
 flash_llseek(struct file *file, long long offset, int origin)
 {
-	lock_kernel();
+	mutex_lock(&flash_mutex);
 	switch (origin) {
 		case 0:
 			file->f_pos = offset;
@@ -94,10 +95,10 @@ flash_llseek(struct file *file, long long offset, int origin)
 			file->f_pos = flash.read_size;
 			break;
 		default:
-			unlock_kernel();
+			mutex_unlock(&flash_mutex);
 			return -EINVAL;
 	}
-	unlock_kernel();
+	mutex_unlock(&flash_mutex);
 	return file->f_pos;
 }
 
@@ -125,13 +126,13 @@ flash_read(struct file * file, char __user * buf,
 static int
 flash_open(struct inode *inode, struct file *file)
 {
-	lock_kernel();
+	mutex_lock(&flash_mutex);
 	if (test_and_set_bit(0, (void *)&flash.busy) != 0) {
-		unlock_kernel();
+		mutex_unlock(&flash_mutex);
 		return -EBUSY;
 	}
 
-	unlock_kernel();
+	mutex_unlock(&flash_mutex);
 	return 0;
 }