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rpc: Push down the ioctl BKL into the RPC code

PATCH In review Alan Cox 2 participants 2 messages May 22, 2008 – Jun 2, 2008

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Alan Cox

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#0 lore raw

PATCH 1/1 rpc: Push down the ioctl BKL into the RPC code

One or two bits I couldn't figure out if the BKL could be dropped for

Signed-off-by Alan Cox <[email protected]>
net/sunrpc/cache.c +4 -4
index c996671..0c1af5d 100644
@@ -826,11 +826,11 @@ cache_poll(struct file *filp, poll_table *wait)
 	return mask;
 }
 
-static int
-cache_ioctl(struct inode *ino, struct file *filp,
-	    unsigned int cmd, unsigned long arg)
+static long
+cache_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
 	int len = 0;
+	struct inode *ino = filp->f_path.dentry->d_inode;
 	struct cache_reader *rp = filp->private_data;
 	struct cache_queue *cq;
 	struct cache_detail *cd = PDE(ino)->data;

@@ -918,7 +918,7 @@ static const struct file_operations cache_file_operations = {
 	.read		= cache_read,
 	.write		= cache_write,
 	.poll		= cache_poll,
-	.ioctl		= cache_ioctl, /* for FIONREAD */
+	.unlocked_ioctl	= cache_ioctl, /* for FIONREAD */
 	.open		= cache_open,
 	.release	= cache_release,
 };
net/sunrpc/rpc_pipe.c +8 -5
index 5a9b0e7..80bca08 100644
@@ -296,23 +296,26 @@ rpc_pipe_poll(struct file *filp, struct poll_table_struct *wait)
 	return mask;
 }
 
-static int
-rpc_pipe_ioctl(struct inode *ino, struct file *filp,
-		unsigned int cmd, unsigned long arg)
+static long
+rpc_pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
 	struct rpc_inode *rpci = RPC_I(filp->f_path.dentry->d_inode);
 	int len;
 
 	switch (cmd) {
 	case FIONREAD:
-		if (rpci->ops == NULL)
+		lock_kernel();
+		if (rpci->ops == NULL) {
+			unlock_kernel();
 			return -EPIPE;
+		}
 		len = rpci->pipelen;
 		if (filp->private_data) {
 			struct rpc_pipe_msg *msg;
 			msg = (struct rpc_pipe_msg *)filp->private_data;
 			len += msg->len - msg->copied;
 		}
+		unlock_kernel();
 		return put_user(len, (int __user *)arg);
 	default:
 		return -EINVAL;

@@ -325,7 +328,7 @@ static const struct file_operations rpc_pipe_fops = {
 	.read		= rpc_pipe_read,
 	.write		= rpc_pipe_write,
 	.poll		= rpc_pipe_poll,
-	.ioctl		= rpc_pipe_ioctl,
+	.unlocked_ioctl	= rpc_pipe_ioctl,
 	.open		= rpc_pipe_open,
 	.release	= rpc_pipe_release,
 };
#1 lore raw
Quoted 3 lines · Alan Cox

One or two bits I couldn't figure out if the BKL could be dropped for

Signed-off-by Alan Cox <[email protected]>

Ack to the net/sunrpc/cache.c change.

The net/sunrpc/rpc_pipe.c changes look fine too, except that there's no point keeping the BKL anywhere there.

As a matter of fact I think that rpc_pipe_ioctl *is* racy, but that's a preexisting problem--it needs the i_lock or i_mutex, not the BKL.

(I'm not sure how important the rpci->ops check is, but the "len" calculation would make more sense if it were atomic, and couldn't the separate check and dereference of filp->private data lead to a null deference?)

--b.

Quoted 77 lines
net/sunrpc/cache.c +4 -4
index c996671..0c1af5d 100644
@@ -826,11 +826,11 @@ cache_poll(struct file *filp, poll_table *wait)
 	return mask;
 }
 
-static int
-cache_ioctl(struct inode *ino, struct file *filp,
-	    unsigned int cmd, unsigned long arg)
+static long
+cache_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
 	int len = 0;
+	struct inode *ino = filp->f_path.dentry->d_inode;
 	struct cache_reader *rp = filp->private_data;
 	struct cache_queue *cq;
 	struct cache_detail *cd = PDE(ino)->data;

@@ -918,7 +918,7 @@ static const struct file_operations cache_file_operations = {
 	.read		= cache_read,
 	.write		= cache_write,
 	.poll		= cache_poll,
-	.ioctl		= cache_ioctl, /* for FIONREAD */
+	.unlocked_ioctl	= cache_ioctl, /* for FIONREAD */
 	.open		= cache_open,
 	.release	= cache_release,
 };
net/sunrpc/rpc_pipe.c +8 -6
index 5a9b0e7..80bca08 100644
@@ -296,23 +296,26 @@ rpc_pipe_poll(struct file *filp, struct poll_table_struct *wait)
 	return mask;
 }
 
-static int
-rpc_pipe_ioctl(struct inode *ino, struct file *filp,
-		unsigned int cmd, unsigned long arg)
+static long
+rpc_pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
 	struct rpc_inode *rpci = RPC_I(filp->f_path.dentry->d_inode);
 	int len;
 
 	switch (cmd) {
 	case FIONREAD:
-		if (rpci->ops == NULL)
+		lock_kernel();
+		if (rpci->ops == NULL) {
+			unlock_kernel();
 			return -EPIPE;
+		}
 		len = rpci->pipelen;
 		if (filp->private_data) {
 			struct rpc_pipe_msg *msg;
 			msg = (struct rpc_pipe_msg *)filp->private_data;
 			len += msg->len - msg->copied;
 		}
+		unlock_kernel();
 		return put_user(len, (int __user *)arg);
 	default:
 		return -EINVAL;

@@ -325,7 +328,7 @@ static const struct file_operations rpc_pipe_fops = {
 	.read		= rpc_pipe_read,
 	.write		= rpc_pipe_write,
 	.poll		= rpc_pipe_poll,
-	.ioctl		= rpc_pipe_ioctl,
+	.unlocked_ioctl	= rpc_pipe_ioctl,
 	.open		= rpc_pipe_open,
 	.release	= rpc_pipe_release,
 };
--

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