scsi: 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: linux-scsi@vger.kernel.org
Cc: "James E.J. Bottomley" <James.Bottomley@suse.de>

1 files changed, 7 insertions, 5 deletions

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 78d6163..b5507d5 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -49,7 +49,7 @@ static int sg_version_num = 30534;	/* 2 digits for each component */
 #include <linux/blkdev.h>
 #include <linux/delay.h>
 #include <linux/blktrace_api.h>
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
 
 #include "scsi.h"
 #include <scsi/scsi_dbg.h>
@@ -103,6 +103,8 @@ static int scatter_elem_sz_prev = SG_SCATTER_SZ;
 static int sg_add(struct device *, struct class_interface *);
 static void sg_remove(struct device *, struct class_interface *);
 
+static DEFINE_MUTEX(sg_mutex);
+
 static DEFINE_IDR(sg_index_idr);
 static DEFINE_RWLOCK(sg_index_lock);	/* Also used to lock
 							   file descriptor list for device */
@@ -229,7 +231,7 @@ sg_open(struct inode *inode, struct file *filp)
 	int res;
 	int retval;
 
-	lock_kernel();
+	mutex_lock(&sg_mutex);
 	nonseekable_open(inode, filp);
 	SCSI_LOG_TIMEOUT(3, printk("sg_open: dev=%d, flags=0x%x\n", dev, flags));
 	sdp = sg_get_dev(dev);
@@ -314,7 +316,7 @@ sdp_put:
 sg_put:
 	if (sdp)
 		sg_put_dev(sdp);
-	unlock_kernel();
+	mutex_unlock(&sg_mutex);
 	return retval;
 }
 
@@ -1092,9 +1094,9 @@ sg_unlocked_ioctl(struct file *filp, unsigned int cmd_in, unsigned long arg)
 {
 	int ret;
 
-	lock_kernel();
+	mutex_lock(&sg_mutex);
 	ret = sg_ioctl(filp, cmd_in, arg);
-	unlock_kernel();
+	mutex_unlock(&sg_mutex);
 
 	return ret;
 }