From: Linus Torvalds torvalds@linux-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@gmail.com Cc: Christoph Hellwig hch@lst.de Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: Al Viro viro@zeniv.linux.org.uk Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.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 0c11c65d27431..623738d8e32c8 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, @@ -840,16 +842,17 @@ 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); @@ -865,10 +868,9 @@ 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() @@ -876,7 +878,7 @@ 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; } @@ -903,10 +905,10 @@ 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; @@ -919,11 +921,9 @@ 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) @@ -2945,7 +2945,7 @@ 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; }