2008-01-09 05:51:47

by Nikanth Karthikesan

Subject: [PATCH] Change x86 Machine check handler to use unlocked_iocl instead of ioctl

The Machine check handler registers ioctl handler that is called
with the BKL held. Changing to register unlocked_ioctl instead.
Also mce ioctl handler does not seem to need any lock protection.

To: Andi Kleen <[email protected]>
Cc: [email protected]
Cc: [email protected]

Change the Machine check handler to use unlocked_ioctl instead of
ioctl handler. Also the mce ioctl handler does not need any lock
protection.

Signed-off-by: Nikanth Karthikesan <[email protected]>

---

diff --git a/arch/x86/kernel/cpu/mcheck/mce_64.c
b/arch/x86/kernel/cpu/mcheck/mce_64.c
index 4b21d29..d3baa62 100644
--- a/arch/x86/kernel/cpu/mcheck/mce_64.c
+++ b/arch/x86/kernel/cpu/mcheck/mce_64.c
@@ -634,8 +634,7 @@ static unsigned int mce_poll(struct file *file,
poll_table *wait)
return 0;
}

-static int mce_ioctl(struct inode *i, struct file *f,unsigned int cmd,
- unsigned long arg)
+static long mce_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
{
int __user *p = (int __user *)arg;

@@ -664,7 +663,7 @@ static const struct file_operations mce_chrdev_ops = {
.release = mce_release,
.read = mce_read,
.poll = mce_poll,
- .ioctl = mce_ioctl,
+ .unlocked_ioctl = mce_ioctl,
};

static struct miscdevice mce_log_device = {

2008-01-09 06:03:11

by Andi Kleen

Subject: Re: [PATCH] Change x86 Machine check handler to use unlocked_iocl instead of ioctl

On Thu, Jan 10, 2008 at 11:25:14AM +0530, Nikanth Karthikesan wrote:
> The Machine check handler registers ioctl handler that is called
> with the BKL held. Changing to register unlocked_ioctl instead.
> Also mce ioctl handler does not seem to need any lock protection.

Thanks, but I already did that here on my own.

-Andi

2008-01-09 10:20:43

by Ingo Molnar

Subject: Re: [PATCH] Change x86 Machine check handler to use unlocked_iocl instead of ioctl

* Nikanth Karthikesan <[email protected]> wrote:

> The Machine check handler registers ioctl handler that is called with
> the BKL held. Changing to register unlocked_ioctl instead. Also mce
> ioctl handler does not seem to need any lock protection.
>
> Change the Machine check handler to use unlocked_ioctl instead of
> ioctl handler. Also the mce ioctl handler does not need any lock
> protection.

thanks, applied to x86.git. Mcelog functionality uses cmpxchg so no need
for the BKL there. The ioctl still being BKL is purely historic and it
was never relied on.

Ingo