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hpet: kill BKL, add compat_ioctl
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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>
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@arndb
arndb committed Sep 15, 2010
1 parent 49553c2 commit 54066a5
Showing 1 changed file with 64 additions and 34 deletions.
98 changes: 64 additions & 34 deletions drivers/char/hpet.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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>

Expand Down Expand Up @@ -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 */
Expand Down Expand Up @@ -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)
Expand All @@ -264,15 +266,15 @@ 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;
}

file->private_data = devp;
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);

Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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:
Expand All @@ -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;
Expand All @@ -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,
Expand Down

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