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, 5 deletions

diff --git a/drivers/char/apm-emulation.c b/drivers/char/apm-emulation.c
index 033e1505fca9..6a420baea268 100644
--- a/drivers/char/apm-emulation.c
+++ b/drivers/char/apm-emulation.c
@@ -13,7 +13,7 @@
 #include <linux/module.h>
 #include <linux/poll.h>
 #include <linux/slab.h>
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
 #include <linux/miscdevice.h>
@@ -126,6 +126,7 @@ struct apm_user {
 /*
  * Local variables
  */
+static DEFINE_MUTEX(apm_mutex);
 static atomic_t suspend_acks_pending = ATOMIC_INIT(0);
 static atomic_t userspace_notification_inhibit = ATOMIC_INIT(0);
 static int apm_disabled;
@@ -274,7 +275,7 @@ apm_ioctl(struct file *filp, u_int cmd, u_long arg)
         if (!as->suser || !as->writer)
                 return -EPERM;
 
-        lock_kernel();
+        mutex_lock(&apm_mutex);
         switch (cmd) {
         case APM_IOC_SUSPEND:
                 mutex_lock(&state_lock);
@@ -335,7 +336,7 @@ apm_ioctl(struct file *filp, u_int cmd, u_long arg)
                 mutex_unlock(&state_lock);
                 break;
         }
-        unlock_kernel();
+        mutex_unlock(&apm_mutex);
 
         return err;
 }
@@ -370,7 +371,7 @@ static int apm_open(struct inode * inode, struct file * filp)
 {
         struct apm_user *as;
 
-        lock_kernel();
+        mutex_lock(&apm_mutex);
         as = kzalloc(sizeof(*as), GFP_KERNEL);
         if (as) {
                 /*
@@ -390,7 +391,7 @@ static int apm_open(struct inode * inode, struct file * filp)
 
                 filp->private_data = as;
         }
-        unlock_kernel();
+        mutex_unlock(&apm_mutex);
 
         return as ? 0 : -ENOMEM;
 }