linux-kernel - [PATCH v2 1/1] misc: hpilo: switch .{read,write} ops to .{read,write}

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Date:   Thu, 14 Jul 2022 01:54:52 +0800
From:   matt.hsiao@....com
To:     linux-kernel@...r.kernel.org
Cc:     arnd@...db.de, gregkh@...uxfoundation.org, jerry.hoemann@....com,
        scott.norton@....com, camille.lu@....com, geoffrey.ndu@....com,
        gustavo.knuppe@....com, Matt Hsiao <matt.hsiao@....com>
Subject: [PATCH v2 1/1] misc: hpilo: switch .{read,write} ops to .{read,write}_iter

From: Matt Hsiao <matt.hsiao@....com>

Commit 4d03e3cc59828c82ee89 ("fs: don't allow kernel reads and writes
without iter ops") requested exclusive .{read,write}_iter ops for
kernel_{read,write}. To support dependent drivers to access hpilo by
kernel_{read,write}, switch .{read,write} ops to their iter variants.

Signed-off-by: Matt Hsiao <matt.hsiao@....com>
---
 drivers/misc/hpilo.c | 31 ++++++++++++++++++-------------
 1 file changed, 18 insertions(+), 13 deletions(-)

diff --git a/drivers/misc/hpilo.c b/drivers/misc/hpilo.c
index 8d00df9243c4..5d431a56b7eb 100644
--- a/drivers/misc/hpilo.c
+++ b/drivers/misc/hpilo.c
@@ -23,6 +23,7 @@
 #include <linux/wait.h>
 #include <linux/poll.h>
 #include <linux/slab.h>
+#include <linux/uio.h>
 #include "hpilo.h"
 
 static struct class *ilo_class;
@@ -435,14 +436,14 @@ static void ilo_set_reset(struct ilo_hwinfo *hw)
 	}
 }
 
-static ssize_t ilo_read(struct file *fp, char __user *buf,
-			size_t len, loff_t *off)
+static ssize_t ilo_read_iter(struct kiocb *iocb, struct iov_iter *to)
 {
-	int err, found, cnt, pkt_id, pkt_len;
-	struct ccb_data *data = fp->private_data;
+	int err = 0, found, cnt, pkt_id, pkt_len;
+	struct ccb_data *data = iocb->ki_filp->private_data;
 	struct ccb *driver_ccb = &data->driver_ccb;
 	struct ilo_hwinfo *hw = data->ilo_hw;
 	void *pkt;
+	size_t len = iov_iter_count(to), copied;
 
 	if (is_channel_reset(driver_ccb)) {
 		/*
@@ -477,7 +478,9 @@ static ssize_t ilo_read(struct file *fp, char __user *buf,
 	if (pkt_len < len)
 		len = pkt_len;
 
-	err = copy_to_user(buf, pkt, len);
+	copied = copy_to_iter(pkt, len, to);
+	if (unlikely(copied != len))
+		err = -EFAULT;
 
 	/* return the received packet to the queue */
 	ilo_pkt_enqueue(hw, driver_ccb, RECVQ, pkt_id, desc_mem_sz(1));
@@ -485,14 +488,14 @@ static ssize_t ilo_read(struct file *fp, char __user *buf,
 	return err ? -EFAULT : len;
 }
 
-static ssize_t ilo_write(struct file *fp, const char __user *buf,
-			 size_t len, loff_t *off)
+static ssize_t ilo_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
-	int err, pkt_id, pkt_len;
-	struct ccb_data *data = fp->private_data;
+	int err = 0, pkt_id, pkt_len;
+	struct ccb_data *data = iocb->ki_filp->private_data;
 	struct ccb *driver_ccb = &data->driver_ccb;
 	struct ilo_hwinfo *hw = data->ilo_hw;
 	void *pkt;
+	size_t len = iov_iter_count(from), copied;
 
 	if (is_channel_reset(driver_ccb))
 		return -ENODEV;
@@ -506,9 +509,11 @@ static ssize_t ilo_write(struct file *fp, const char __user *buf,
 		len = pkt_len;
 
 	/* on failure, set the len to 0 to return empty packet to the device */
-	err = copy_from_user(pkt, buf, len);
-	if (err)
+	copied = copy_from_iter(pkt, len, from);
+	if (unlikely(copied != len)) {
 		len = 0;
+		err = -EFAULT;
+	}
 
 	/* send the packet */
 	ilo_pkt_enqueue(hw, driver_ccb, SENDQ, pkt_id, len);
@@ -639,8 +644,8 @@ static int ilo_open(struct inode *ip, struct file *fp)
 
 static const struct file_operations ilo_fops = {
 	.owner		= THIS_MODULE,
-	.read		= ilo_read,
-	.write		= ilo_write,
+	.read_iter	= ilo_read_iter,
+	.write_iter	= ilo_write_iter,
 	.poll		= ilo_poll,
 	.open 		= ilo_open,
 	.release 	= ilo_close,
-- 
2.16.6