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

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Message-ID: <20080522231727.4b0c4da4@core>
Date:	Thu, 22 May 2008 23:17:27 +0100
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	Sam Ravnborg <sam@...nborg.org>
Cc:	linux-kernel@...r.kernel.org, rmk@....linux.org.uk
Subject: Re: [PATCH] apm_emu: push BKL down into ioctl handlers

On Thu, 22 May 2008 22:40:59 +0200
Sam Ravnborg <sam@...nborg.org> 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@...hat.com>
> -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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