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, 5 insertions, 4 deletions

diff --git a/drivers/char/snsc.c b/drivers/char/snsc.c
index 32b74de18f5f..208e25731dfe 100644
--- a/drivers/char/snsc.c
+++ b/drivers/char/snsc.c
@@ -21,7 +21,7 @@
 #include <linux/poll.h>
 #include <linux/module.h>
 #include <linux/slab.h>
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
 #include <asm/sn/io.h>
 #include <asm/sn/sn_sal.h>
 #include <asm/sn/module.h>
@@ -34,6 +34,7 @@
 #define SCDRV_BUFSZ     2048
 #define SCDRV_TIMEOUT   1000
 
+static DEFINE_MUTEX(scdrv_mutex);
 static irqreturn_t
 scdrv_interrupt(int irq, void *subch_data)
 {
@@ -105,7 +106,7 @@ scdrv_open(struct inode *inode, struct file *file)
         file->private_data = sd;
 
         /* hook this subchannel up to the system controller interrupt */
-        lock_kernel();
+        mutex_lock(&scdrv_mutex);
         rv = request_irq(SGI_UART_VECTOR, scdrv_interrupt,
                          IRQF_SHARED | IRQF_DISABLED,
                          SYSCTL_BASENAME, sd);
@@ -113,10 +114,10 @@ scdrv_open(struct inode *inode, struct file *file)
                 ia64_sn_irtr_close(sd->sd_nasid, sd->sd_subch);
                 kfree(sd);
                 printk("%s: irq request failed (%d)\n", __func__, rv);
-                unlock_kernel();
+                mutex_unlock(&scdrv_mutex);
                 return -EBUSY;
         }
-        unlock_kernel();
+        mutex_unlock(&scdrv_mutex);
         return 0;
 }