Re: [PATCH] snapshot: Push BKL down into ioctl handlers
From: Rafael J. Wysocki
Date: Thu May 22 2008 - 21:09:30 EST
On Thursday, 22 of May 2008, Alan Cox wrote:
> Signed-off-by: Alan Cox <alan@xxxxxxxxxx>
>
> diff --git a/kernel/power/user.c b/kernel/power/user.c
> index f5512cb..658262b 100644
> --- a/kernel/power/user.c
> +++ b/kernel/power/user.c
> @@ -23,6 +23,7 @@
> #include <linux/console.h>
> #include <linux/cpu.h>
> #include <linux/freezer.h>
> +#include <linux/smp_lock.h>
>
> #include <asm/uaccess.h>
>
> @@ -164,8 +165,8 @@ static ssize_t snapshot_write(struct file *filp, const char __user *buf,
> return res;
> }
>
> -static int snapshot_ioctl(struct inode *inode, struct file *filp,
> - unsigned int cmd, unsigned long arg)
> +static long snapshot_ioctl(struct file *filp, unsigned int cmd,
> + unsigned long arg)
> {
> int error = 0;
> struct snapshot_data *data;
> @@ -181,6 +182,8 @@ static int snapshot_ioctl(struct inode *inode, struct file *filp,
>
> data = filp->private_data;
>
> + lock_kernel();
> +
Hm, well, I admit I'm a bit ignorant as far as the chardev locking is
concerned, but can you please tell me why would that be wrong if we didn't call
lock_kernel() here at all?
> switch (cmd) {
>
> case SNAPSHOT_FREEZE:
> @@ -389,7 +392,7 @@ static int snapshot_ioctl(struct inode *inode, struct file *filp,
> error = -ENOTTY;
>
> }
> -
> + unlock_kernel();
> return error;
> }
>
> @@ -399,7 +402,7 @@ static const struct file_operations snapshot_fops = {
> .read = snapshot_read,
> .write = snapshot_write,
> .llseek = no_llseek,
> - .ioctl = snapshot_ioctl,
> + .unlocked_ioctl = snapshot_ioctl,
> };
>
> static struct miscdevice snapshot_device = {
Thanks,
Rafael
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/