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Date: Mon, 1 Mar 2021 17:06:25 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Oliver Giles <ohw.giles@...il.com>,
Christoph Hellwig <hch@....de>,
Al Viro <viro@...iv.linux.org.uk>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.10 137/663] tty: implement read_iter
From: Linus Torvalds <torvalds@...ux-foundation.org>
[ Upstream commit dd78b0c483e33225e0e0782b0ed887129b00f956 ]
Now that the ldisc read() function takes kernel pointers, it's fairly
straightforward to make the tty file operations use .read_iter() instead
of .read().
That automatically gives us vread() and friends, and also makes it
possible to do .splice_read() on ttys again.
Fixes: 36e2c7421f02 ("fs: don't allow splice read/write without explicit ops")
Reported-by: Oliver Giles <ohw.giles@...il.com>
Cc: Christoph Hellwig <hch@....de>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
drivers/tty/tty_io.c | 36 ++++++++++++++++++------------------
1 file changed, 18 insertions(+), 18 deletions(-)
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index a50c8a4318228..3f55fe7293f31 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -142,7 +142,7 @@ LIST_HEAD(tty_drivers); /* linked list of tty drivers */
/* Mutex to protect creating and releasing a tty */
DEFINE_MUTEX(tty_mutex);
-static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
+static ssize_t tty_read(struct kiocb *, struct iov_iter *);
static ssize_t tty_write(struct kiocb *, struct iov_iter *);
static __poll_t tty_poll(struct file *, poll_table *);
static int tty_open(struct inode *, struct file *);
@@ -473,8 +473,9 @@ static void tty_show_fdinfo(struct seq_file *m, struct file *file)
static const struct file_operations tty_fops = {
.llseek = no_llseek,
- .read = tty_read,
+ .read_iter = tty_read,
.write_iter = tty_write,
+ .splice_read = generic_file_splice_read,
.splice_write = iter_file_splice_write,
.poll = tty_poll,
.unlocked_ioctl = tty_ioctl,
@@ -487,8 +488,9 @@ static const struct file_operations tty_fops = {
static const struct file_operations console_fops = {
.llseek = no_llseek,
- .read = tty_read,
+ .read_iter = tty_read,
.write_iter = redirected_tty_write,
+ .splice_read = generic_file_splice_read,
.splice_write = iter_file_splice_write,
.poll = tty_poll,
.unlocked_ioctl = tty_ioctl,
@@ -841,16 +843,17 @@ static void tty_update_time(struct timespec64 *time)
* data or clears the cookie. The cookie may be something that the
* ldisc maintains state for and needs to free.
*/
-static int iterate_tty_read(struct tty_ldisc *ld, struct tty_struct *tty, struct file *file,
- char __user *buf, size_t count)
+static int iterate_tty_read(struct tty_ldisc *ld, struct tty_struct *tty,
+ struct file *file, struct iov_iter *to)
{
int retval = 0;
void *cookie = NULL;
unsigned long offset = 0;
char kernel_buf[64];
+ size_t count = iov_iter_count(to);
do {
- int size, uncopied;
+ int size, copied;
size = count > sizeof(kernel_buf) ? sizeof(kernel_buf) : count;
size = ld->ops->read(tty, file, kernel_buf, size, &cookie, offset);
@@ -866,10 +869,9 @@ static int iterate_tty_read(struct tty_ldisc *ld, struct tty_struct *tty, struct
return size;
}
- uncopied = copy_to_user(buf+offset, kernel_buf, size);
- size -= uncopied;
- offset += size;
- count -= size;
+ copied = copy_to_iter(kernel_buf, size, to);
+ offset += copied;
+ count -= copied;
/*
* If the user copy failed, we still need to do another ->read()
@@ -877,7 +879,7 @@ static int iterate_tty_read(struct tty_ldisc *ld, struct tty_struct *tty, struct
*
* But make sure size is zeroed.
*/
- if (unlikely(uncopied)) {
+ if (unlikely(copied != size)) {
count = 0;
retval = -EFAULT;
}
@@ -904,10 +906,10 @@ static int iterate_tty_read(struct tty_ldisc *ld, struct tty_struct *tty, struct
* read calls may be outstanding in parallel.
*/
-static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
- loff_t *ppos)
+static ssize_t tty_read(struct kiocb *iocb, struct iov_iter *to)
{
int i;
+ struct file *file = iocb->ki_filp;
struct inode *inode = file_inode(file);
struct tty_struct *tty = file_tty(file);
struct tty_ldisc *ld;
@@ -920,11 +922,9 @@ static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
/* We want to wait for the line discipline to sort out in this
situation */
ld = tty_ldisc_ref_wait(tty);
- if (!ld)
- return hung_up_tty_read(file, buf, count, ppos);
i = -EIO;
- if (ld->ops->read)
- i = iterate_tty_read(ld, tty, file, buf, count);
+ if (ld && ld->ops->read)
+ i = iterate_tty_read(ld, tty, file, to);
tty_ldisc_deref(ld);
if (i > 0)
@@ -2943,7 +2943,7 @@ static long tty_compat_ioctl(struct file *file, unsigned int cmd,
static int this_tty(const void *t, struct file *file, unsigned fd)
{
- if (likely(file->f_op->read != tty_read))
+ if (likely(file->f_op->read_iter != tty_read))
return 0;
return file_tty(file) != t ? 0 : fd + 1;
}
--
2.27.0
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