USB: 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, 4 insertions, 3 deletions

diff --git a/drivers/usb/gadget/printer.c b/drivers/usb/gadget/printer.c
index 88f05996aa02..cf241c371a71 100644
--- a/drivers/usb/gadget/printer.c
+++ b/drivers/usb/gadget/printer.c
@@ -25,7 +25,7 @@
 #include <linux/ioport.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
 #include <linux/errno.h>
 #include <linux/init.h>
 #include <linux/timer.h>
@@ -70,6 +70,7 @@
 #define DRIVER_DESC             "Printer Gadget"
 #define DRIVER_VERSION          "2007 OCT 06"
 
+static DEFINE_MUTEX(printer_mutex);
 static const char shortname [] = "printer";
 static const char driver_desc [] = DRIVER_DESC;
 
@@ -476,7 +477,7 @@ printer_open(struct inode *inode, struct file *fd)
         unsigned long           flags;
         int                     ret = -EBUSY;
 
-        lock_kernel();
+        mutex_lock(&printer_mutex);
         dev = container_of(inode->i_cdev, struct printer_dev, printer_cdev);
 
         spin_lock_irqsave(&dev->lock, flags);
@@ -492,7 +493,7 @@ printer_open(struct inode *inode, struct file *fd)
         spin_unlock_irqrestore(&dev->lock, flags);
 
         DBG(dev, "printer_open returned %x\n", ret);
-        unlock_kernel();
+        mutex_unlock(&printer_mutex);
         return ret;
 }