Re: [PATCH] apm_emu: push BKL down into ioctl handlers

From: Alan Cox
Date: Thu May 22 2008 - 18:30:46 EST


On Thu, 22 May 2008 22:40:59 +0200
Sam Ravnborg <sam@xxxxxxxxxxxx> wrote:

> On Thu, May 22, 2008 at 09:23:41PM +0100, Alan Cox wrote:
> > Part of the elimination of the old lock based ioctl. This one can
> > probably lose the remaining BKL pretty trivially
> >
> > Signed-off-by: Alan Cox <alan@xxxxxxxxxx>
> -ENOPATCH

Must be race between the sending gnomes and the pasting gnome ;)

diff --git a/drivers/char/apm-emulation.c b/drivers/char/apm-emulation.c
index cdd876d..4ea7188 100644
--- a/drivers/char/apm-emulation.c
+++ b/drivers/char/apm-emulation.c
@@ -29,6 +29,7 @@
#include <linux/completion.h>
#include <linux/kthread.h>
#include <linux/delay.h>
+#include <linux/smp_lock.h>

#include <asm/system.h>

@@ -292,8 +293,7 @@ static unsigned int apm_poll(struct file *fp, poll_table * wait)
* Only when everyone who has opened /dev/apm_bios with write permission
* has acknowledge does the actual suspend happen.
*/
-static int
-apm_ioctl(struct inode * inode, struct file *filp, u_int cmd, u_long arg)
+static long apm_ioctl(struct file *filp, u_int cmd, u_long arg)
{
struct apm_user *as = filp->private_data;
int err = -EINVAL;
@@ -301,6 +301,8 @@ apm_ioctl(struct inode * inode, struct file *filp, u_int cmd, u_long arg)
if (!as->suser || !as->writer)
return -EPERM;

+ lock_kernel();
+
switch (cmd) {
case APM_IOC_SUSPEND:
mutex_lock(&state_lock);
@@ -378,7 +380,7 @@ apm_ioctl(struct inode * inode, struct file *filp, u_int cmd, u_long arg)
mutex_unlock(&state_lock);
break;
}
-
+ unlock_kernel();
return err;
}

@@ -443,7 +445,7 @@ static struct file_operations apm_bios_fops = {
.owner = THIS_MODULE,
.read = apm_read,
.poll = apm_poll,
- .ioctl = apm_ioctl,
+ .unlocked_ioctl = apm_ioctl,
.open = apm_open,
.release = apm_release,
};
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