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, 8 insertions, 7 deletions

diff --git a/drivers/char/ds1302.c b/drivers/char/ds1302.c
index 170693c93c73..e3d72aa3cbd2 100644
--- a/drivers/char/ds1302.c
+++ b/drivers/char/ds1302.c
@@ -20,7 +20,7 @@
 #include <linux/miscdevice.h>
 #include <linux/delay.h>
 #include <linux/bcd.h>
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
 #include <linux/uaccess.h>
 #include <linux/io.h>
 
@@ -32,6 +32,7 @@
 
 #define RTC_MAJOR_NR 121 /* local major, change later */
 
+static DEFINE_MUTEX(rtc_mutex);
 static const char ds1302_name[] = "ds1302";
 
 /* Send 8 bits. */
@@ -164,9 +165,9 @@ static long rtc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
                         struct rtc_time rtc_tm;
 
                         memset(&rtc_tm, 0, sizeof (struct rtc_time));
-                        lock_kernel();
+                        mutex_lock(&rtc_mutex);
                         get_rtc_time(&rtc_tm);
-                        unlock_kernel();
+                        mutex_unlock(&rtc_mutex);
                         if (copy_to_user((struct rtc_time*)arg, &rtc_tm, sizeof(struct rtc_time)))
                                 return -EFAULT;
                         return 0;
@@ -218,7 +219,7 @@ static long rtc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
                         mon = bin2bcd(mon);
                         yrs = bin2bcd(yrs);
 
-                        lock_kernel();
+                        mutex_lock(&rtc_mutex);
                         local_irq_save(flags);
                         CMOS_WRITE(yrs, RTC_YEAR);
                         CMOS_WRITE(mon, RTC_MONTH);
@@ -227,7 +228,7 @@ static long rtc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
                         CMOS_WRITE(min, RTC_MINUTES);
                         CMOS_WRITE(sec, RTC_SECONDS);
                         local_irq_restore(flags);
-                        unlock_kernel();
+                        mutex_unlock(&rtc_mutex);
 
                         /* Notice that at this point, the RTC is updated but
                          * the kernel is still running with the old time.
@@ -247,10 +248,10 @@ static long rtc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
                         if(copy_from_user(&tcs_val, (int*)arg, sizeof(int)))
                                 return -EFAULT;
 
-                        lock_kernel();
+                        mutex_lock(&rtc_mutex);
                         tcs_val = RTC_TCR_PATTERN | (tcs_val & 0x0F);
                         ds1302_writereg(RTC_TRICKLECHARGER, tcs_val);
-                        unlock_kernel();
+                        mutex_unlock(&rtc_mutex);
                         return 0;
                 }
                 default: