This is a note to let you know that I've just added the patch titled
tty: clean up legacy leftovers from n_tty line discipline
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tty-clean-up-legacy-leftovers-from-n_tty-line-discipline.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 64a69892afadd6fffaeadc65427bb7601161139d Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Date: Tue, 19 Jan 2021 13:46:28 -0800
Subject: tty: clean up legacy leftovers from n_tty line discipline
From: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
commit 64a69892afadd6fffaeadc65427bb7601161139d upstream.
Back when the line disciplines did their own direct user accesses, they
had to deal with the data copy possibly failing in the middle.
Now that the user copy is done by the tty_io.c code, that failure case
no longer exists.
Remove the left-over error handling code that cannot trigger.
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/n_tty.c | 29 +++++++++--------------------
1 file changed, 9 insertions(+), 20 deletions(-)
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -1955,19 +1955,17 @@ static inline int input_available_p(stru
* read_tail published
*/
-static int copy_from_read_buf(struct tty_struct *tty,
+static void copy_from_read_buf(struct tty_struct *tty,
unsigned char **kbp,
size_t *nr)
{
struct n_tty_data *ldata = tty->disc_data;
- int retval;
size_t n;
bool is_eof;
size_t head = smp_load_acquire(&ldata->commit_head);
size_t tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
- retval = 0;
n = min(head - ldata->read_tail, N_TTY_BUF_SIZE - tail);
n = min(*nr, n);
if (n) {
@@ -1984,7 +1982,6 @@ static int copy_from_read_buf(struct tty
*kbp += n;
*nr -= n;
}
- return retval;
}
/**
@@ -2010,9 +2007,9 @@ static int copy_from_read_buf(struct tty
* read_tail published
*/
-static int canon_copy_from_read_buf(struct tty_struct *tty,
- unsigned char **kbp,
- size_t *nr)
+static void canon_copy_from_read_buf(struct tty_struct *tty,
+ unsigned char **kbp,
+ size_t *nr)
{
struct n_tty_data *ldata = tty->disc_data;
size_t n, size, more, c;
@@ -2022,7 +2019,7 @@ static int canon_copy_from_read_buf(stru
/* N.B. avoid overrun if nr == 0 */
if (!*nr)
- return 0;
+ return;
n = min(*nr + 1, smp_load_acquire(&ldata->canon_head) - ldata->read_tail);
@@ -2069,7 +2066,6 @@ static int canon_copy_from_read_buf(stru
ldata->push = 0;
tty_audit_push();
}
- return 0;
}
/**
@@ -2219,24 +2215,17 @@ static ssize_t n_tty_read(struct tty_str
}
if (ldata->icanon && !L_EXTPROC(tty)) {
- retval = canon_copy_from_read_buf(tty, &kb, &nr);
- if (retval)
- break;
+ canon_copy_from_read_buf(tty, &kb, &nr);
} else {
- int uncopied;
-
/* Deal with packet mode. */
if (packet && kb == kbuf) {
*kb++ = TIOCPKT_DATA;
nr--;
}
- uncopied = copy_from_read_buf(tty, &kb, &nr);
- uncopied += copy_from_read_buf(tty, &kb, &nr);
- if (uncopied) {
- retval = -EFAULT;
- break;
- }
+ /* See comment above copy_from_read_buf() why twice */
+ copy_from_read_buf(tty, &kb, &nr);
+ copy_from_read_buf(tty, &kb, &nr);
}
n_tty_check_unthrottle(tty);
Patches currently in stable-queue which might be from torvalds@xxxxxxxxxxxxxxxxxxxx are
queue-5.10/tty-teach-the-n_tty-icanon-case-about-the-new-cookie-continuations-too.patch
queue-5.10/tty-teach-n_tty-line-discipline-about-the-new-cookie-continuations.patch
queue-5.10/tty-clean-up-legacy-leftovers-from-n_tty-line-discipline.patch
queue-5.10/tty-fix-up-iterate_tty_read-eoverflow-handling.patch
queue-5.10/mm-hugetlb.c-fix-unnecessary-address-expansion-of-pmd-sharing.patch
queue-5.10/zsmalloc-account-the-number-of-compacted-pages-correctly.patch
queue-5.10/tty-fix-up-hung_up_tty_read-conversion.patch
