From dd78b0c483e33225e0e0782b0ed887129b00f956 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Tue, 19 Jan 2021 10:49:19 -0800 Subject: tty: implement read_iter 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 Cc: Christoph Hellwig Cc: Greg Kroah-Hartman Cc: Al Viro Signed-off-by: Linus Torvalds --- drivers/tty/tty_io.c | 36 ++++++++++++++++++------------------ 1 file changed, 18 insertions(+), 18 deletions(-) (limited to 'drivers/tty') diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index a34f8bcf875e..8846d3b99845 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 *); ssize_t redirected_tty_write(struct kiocb *, struct iov_iter *); static __poll_t tty_poll(struct file *, poll_table *); @@ -476,8 +476,9 @@ 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, @@ -490,8 +491,9 @@ 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, @@ -844,16 +846,17 @@ 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); @@ -869,10 +872,9 @@ 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() @@ -880,7 +882,7 @@ 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; } @@ -907,10 +909,10 @@ 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; @@ -923,11 +925,9 @@ 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) @@ -2927,7 +2927,7 @@ 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; } -- cgit v1.2.3