hpet: kill BKL, add compat_ioctl

hpet uses the big kernel lock in its ioctl and open
functions. Replace this with a private mutex to be
sure. Since we're already touching the ioctl function,
add the compat_ioctl version as well -- all commands
except HPET_INFO are compatible and that one is easy
to add.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Clemens Ladisch <clemens@ladisch.de>
Cc: Bob Picco <bob.picco@hp.com>

1 files changed, 64 insertions, 34 deletions

diff --git a/drivers/char/hpet.c b/drivers/char/hpet.c
index a0a1829d3198..a4eee324eb1e 100644
--- a/drivers/char/hpet.c
+++ b/drivers/char/hpet.c
@@ -30,6 +30,7 @@
 #include <linux/bcd.h>
 #include <linux/seq_file.h>
 #include <linux/bitops.h>
+#include <linux/compat.h>
 #include <linux/clocksource.h>
 #include <linux/slab.h>
 
@@ -67,6 +68,7 @@
 #define read_counter(MC)        readl(MC)
 #endif
 
+static DEFINE_MUTEX(hpet_mutex); /* replaces BKL */
 static u32 hpet_nhpet, hpet_max_freq = HPET_USER_FREQ;
 
 /* This clocksource driver currently only works on ia64 */
@@ -250,7 +252,7 @@ static int hpet_open(struct inode *inode, struct file *file)
         if (file->f_mode & FMODE_WRITE)
                 return -EINVAL;
 
-        lock_kernel();
+        mutex_lock(&hpet_mutex);
         spin_lock_irq(&hpet_lock);
 
         for (devp = NULL, hpetp = hpets; hpetp && !devp; hpetp = hpetp->hp_next)
@@ -264,7 +266,7 @@ static int hpet_open(struct inode *inode, struct file *file)
 
         if (!devp) {
                 spin_unlock_irq(&hpet_lock);
-                unlock_kernel();
+                mutex_unlock(&hpet_mutex);
                 return -EBUSY;
         }
 
@@ -272,7 +274,7 @@ static int hpet_open(struct inode *inode, struct file *file)
         devp->hd_irqdata = 0;
         devp->hd_flags |= HPET_OPEN;
         spin_unlock_irq(&hpet_lock);
-        unlock_kernel();
+        mutex_unlock(&hpet_mutex);
 
         hpet_timer_set_irq(devp);
 
@@ -429,22 +431,6 @@ static int hpet_release(struct inode *inode, struct file *file)
         return 0;
 }
 
-static int hpet_ioctl_common(struct hpet_dev *, int, unsigned long, int);
-
-static long hpet_ioctl(struct file *file, unsigned int cmd,
-                        unsigned long arg)
-{
-        struct hpet_dev *devp;
-        int ret;
-
-        devp = file->private_data;
-        lock_kernel();
-        ret = hpet_ioctl_common(devp, cmd, arg, 0);
-        unlock_kernel();
-
-        return ret;
-}
-
 static int hpet_ioctl_ieon(struct hpet_dev *devp)
 {
         struct hpet_timer __iomem *timer;
@@ -553,7 +539,8 @@ static inline unsigned long hpet_time_div(struct hpets *hpets,
 }
 
 static int
-hpet_ioctl_common(struct hpet_dev *devp, int cmd, unsigned long arg, int kernel)
+hpet_ioctl_common(struct hpet_dev *devp, int cmd, unsigned long arg,
+                  struct hpet_info *info)
 {
         struct hpet_timer __iomem *timer;
         struct hpet __iomem *hpet;
@@ -594,23 +581,15 @@ hpet_ioctl_common(struct hpet_dev *devp, int cmd, unsigned long arg, int kernel)
                 break;
         case HPET_INFO:
                 {
-                        struct hpet_info info;
-
                         if (devp->hd_ireqfreq)
-                                info.hi_ireqfreq =
+                                info->hi_ireqfreq =
                                         hpet_time_div(hpetp, devp->hd_ireqfreq);
                         else
-                                info.hi_ireqfreq = 0;
-                        info.hi_flags =
+                                info->hi_ireqfreq = 0;
+                        info->hi_flags =
                             readq(&timer->hpet_config) & Tn_PER_INT_CAP_MASK;
-                        info.hi_hpet = hpetp->hp_which;
-                        info.hi_timer = devp - hpetp->hp_dev;
-                        if (kernel)
-                                memcpy((void *)arg, &info, sizeof(info));
-                        else
-                                if (copy_to_user((void __user *)arg, &info,
-                                                 sizeof(info)))
-                                        err = -EFAULT;
+                        info->hi_hpet = hpetp->hp_which;
+                        info->hi_timer = devp - hpetp->hp_dev;
                         break;
                 }
         case HPET_EPI:
@@ -636,7 +615,7 @@ hpet_ioctl_common(struct hpet_dev *devp, int cmd, unsigned long arg, int kernel)
                 devp->hd_flags &= ~HPET_PERIODIC;
                 break;
         case HPET_IRQFREQ:
-                if (!kernel && (arg > hpet_max_freq) &&
+                if ((arg > hpet_max_freq) &&
                     !capable(CAP_SYS_RESOURCE)) {
                         err = -EACCES;
                         break;
@@ -653,12 +632,63 @@ hpet_ioctl_common(struct hpet_dev *devp, int cmd, unsigned long arg, int kernel)
         return err;
 }
 
+static long
+hpet_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+        struct hpet_info info;
+        int err;
+
+        mutex_lock(&hpet_mutex);
+        err = hpet_ioctl_common(file->private_data, cmd, arg, &info);
+        mutex_unlock(&hpet_mutex);
+
+        if ((cmd == HPET_INFO) && !err &&
+            (copy_to_user((void __user *)arg, &info, sizeof(info))))
+                err = -EFAULT;
+
+        return err;
+}
+
+#ifdef CONFIG_COMPAT
+struct compat_hpet_info {
+        compat_ulong_t hi_ireqfreq;     /* Hz */
+        compat_ulong_t hi_flags;        /* information */
+        unsigned short hi_hpet;
+        unsigned short hi_timer;
+};
+
+static long
+hpet_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+        struct hpet_info info;
+        int err;
+
+        mutex_lock(&hpet_mutex);
+        err = hpet_ioctl_common(file->private_data, cmd, arg, &info);
+        mutex_unlock(&hpet_mutex);
+
+        if ((cmd == HPET_INFO) && !err) {
+                struct compat_hpet_info __user *u = compat_ptr(arg);
+                if (put_user(info.hi_ireqfreq, &u->hi_ireqfreq) ||
+                    put_user(info.hi_flags, &u->hi_flags) ||
+                    put_user(info.hi_hpet, &u->hi_hpet) ||
+                    put_user(info.hi_timer, &u->hi_timer))
+                        err = -EFAULT;
+        }
+
+        return err;
+}
+#endif
+
 static const struct file_operations hpet_fops = {
         .owner = THIS_MODULE,
         .llseek = no_llseek,
         .read = hpet_read,
         .poll = hpet_poll,
         .unlocked_ioctl = hpet_ioctl,
+#ifdef CONFIG_COMPAT
+        .compat_ioctl = hpet_compat_ioctl,
+#endif
         .open = hpet_open,
         .release = hpet_release,
         .fasync = hpet_fasync,