Staging: 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: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 5 insertions, 4 deletions

diff --git a/drivers/staging/crystalhd/crystalhd_lnx.c b/drivers/staging/crystalhd/crystalhd_lnx.c
index 6083969..fbb80f0 100644
--- a/drivers/staging/crystalhd/crystalhd_lnx.c
+++ b/drivers/staging/crystalhd/crystalhd_lnx.c
@@ -15,11 +15,12 @@
   along with this driver.  If not, see <http://www.gnu.org/licenses/>.
 ***************************************************************************/
 
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
 #include <linux/slab.h>
 
 #include "crystalhd_lnx.h"
 
+static DEFINE_MUTEX(chd_dec_mutex);
 static struct class *crystalhd_class;
 
 static struct crystalhd_adp *g_adp_info;
@@ -277,16 +278,16 @@ static long chd_dec_ioctl(struct file *fd, unsigned int cmd, unsigned long ua)
 		return -ENODATA;
 	}
 
-	lock_kernel();
+	mutex_lock(&chd_dec_mutex);
 	cproc = crystalhd_get_cmd_proc(&adp->cmds, cmd, uc);
 	if (!cproc) {
 		BCMLOG_ERR("Unhandled command: %d\n", cmd);
-		unlock_kernel();
+		mutex_unlock(&chd_dec_mutex);
 		return -EINVAL;
 	}
 
 	ret = chd_dec_api_cmd(adp, ua, uc->uid, cmd, cproc);
-	unlock_kernel();
+	mutex_unlock(&chd_dec_mutex);
 	return ret;
 }