Re: [Fwd: Re: [patch] Real-Time Preemption, -RT-2.6.9-mm1-V0.4]

[Ingo Molnar <mingo@elte.hu>]

* Ingo Molnar <mingo@elte.hu> wrote:

> > correct, and with the changeall-tree hack in addition. And keep your
> > finger near the reset button, just in case ...
> 
> it wont even boot ...
> 
> let me try some more hacks to make this a little bit safer.

ok, next attempt. Please apply this patch and do the changeall-tree
thing in the sound/ directory. This should in theory switch the ALSA
ioctls (and only them) to a BKL-less variant.

	Ingo

--- linux/sound/core/pcm_native.c.orig
+++ linux/sound/core/pcm_native.c	
@@ -3317,7 +3317,7 @@ static struct file_operations snd_pcm_f_
 	.open =		snd_pcm_open,
 	.release =	snd_pcm_release,
 	.poll =		snd_pcm_playback_poll,
-	.ioctl =	snd_pcm_playback_ioctl,
+	.ioctl2 =	snd_pcm_playback_ioctl,
 	.mmap =		snd_pcm_mmap,
 	.fasync =	snd_pcm_fasync,
 };
@@ -3329,7 +3329,7 @@ static struct file_operations snd_pcm_f_
 	.open =		snd_pcm_open,
 	.release =	snd_pcm_release,
 	.poll =		snd_pcm_capture_poll,
-	.ioctl =	snd_pcm_capture_ioctl,
+	.ioctl2 =	snd_pcm_capture_ioctl,
 	.mmap =		snd_pcm_mmap,
 	.fasync =	snd_pcm_fasync,
 };
--- linux/fs/ioctl.c.orig
+++ linux/fs/ioctl.c	
@@ -68,19 +68,26 @@ asmlinkage long sys_ioctl(unsigned int f
                 goto out;
         }
 
-	lock_kernel();
 	switch (cmd) {
 		case FIOCLEX:
+			lock_kernel();
 			set_close_on_exec(fd, 1);
+			unlock_kernel();
 			break;
 
 		case FIONCLEX:
+			lock_kernel();
 			set_close_on_exec(fd, 0);
+			unlock_kernel();
 			break;
 
 		case FIONBIO:
-			if ((error = get_user(on, (int __user *)arg)) != 0)
+			lock_kernel();
+			unlock_kernel();
+			if ((error = get_user(on, (int __user *)arg)) != 0) {
+				unlock_kernel();
 				break;
+			}
 			flag = O_NONBLOCK;
 #ifdef __sparc__
 			/* SunOS compatibility item. */
@@ -91,11 +98,15 @@ asmlinkage long sys_ioctl(unsigned int f
 				filp->f_flags |= flag;
 			else
 				filp->f_flags &= ~flag;
+			unlock_kernel();
 			break;
 
 		case FIOASYNC:
-			if ((error = get_user(on, (int __user *)arg)) != 0)
+			lock_kernel();
+			if ((error = get_user(on, (int __user *)arg)) != 0) {
+				unlock_kernel();
 				break;
+			}
 			flag = on ? FASYNC : 0;
 
 			/* Did FASYNC state change ? */
@@ -104,16 +115,20 @@ asmlinkage long sys_ioctl(unsigned int f
 					error = filp->f_op->fasync(fd, filp, on);
 				else error = -ENOTTY;
 			}
-			if (error != 0)
+			if (error != 0) {
+				unlock_kernel();
 				break;
+			}
 
 			if (on)
 				filp->f_flags |= FASYNC;
 			else
 				filp->f_flags &= ~FASYNC;
+			unlock_kernel();
 			break;
 
 		case FIOQSIZE:
+			lock_kernel();
 			if (S_ISDIR(filp->f_dentry->d_inode->i_mode) ||
 			    S_ISREG(filp->f_dentry->d_inode->i_mode) ||
 			    S_ISLNK(filp->f_dentry->d_inode->i_mode)) {
@@ -122,15 +137,21 @@ asmlinkage long sys_ioctl(unsigned int f
 			}
 			else
 				error = -ENOTTY;
+			unlock_kernel();
 			break;
 		default:
 			error = -ENOTTY;
-			if (S_ISREG(filp->f_dentry->d_inode->i_mode))
+			if (S_ISREG(filp->f_dentry->d_inode->i_mode)) {
+				lock_kernel();
 				error = file_ioctl(filp, cmd, arg);
-			else if (filp->f_op && filp->f_op->ioctl)
+				unlock_kernel();
+			} else if (filp->f_op && filp->f_op->ioctl) {
+				lock_kernel();
 				error = filp->f_op->ioctl(filp->f_dentry->d_inode, filp, cmd, arg);
+				unlock_kernel();
+			} else if (filp->f_op && filp->f_op->ioctl2)
+				error = filp->f_op->ioctl2(filp->f_dentry->d_inode, filp, cmd, arg);
 	}
-	unlock_kernel();
 	fput(filp);
 
 out:
--- linux/include/linux/fs.h.orig
+++ linux/include/linux/fs.h
@@ -993,6 +993,7 @@ struct file_operations {
 	int (*check_flags)(int);
 	int (*dir_notify)(struct file *filp, unsigned long arg);
 	int (*flock) (struct file *, int, struct file_lock *);
+	int (*ioctl2) (struct inode *, struct file *, unsigned int, unsigned long);
 };
 
 struct inode_operations {