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TTY/Serial fixes for 3.15-rc4

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Here are some tty and serial driver fixes for things reported recently.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'tty-3.15-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty/serial fixes from Greg KH:
 "Here are some tty and serial driver fixes for things reported
  recently"

* tag 'tty-3.15-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  tty: Fix lockless tty buffer race
  Revert "tty: Fix race condition between __tty_buffer_request_room and flush_to_ldisc"
  drivers/tty/hvc: don't free hvc_console_setup after init
  n_tty: Fix n_tty_write crash when echoing in raw mode
  tty: serial: 8250_core.c Bug fix for Exar chips.
This commit is contained in:
Linus Torvalds 2014-05-05 15:50:16 -07:00
commit df862f625d
5 changed files with 20 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/tty/hvc/hvc_console.c
View File

@ -190,7 +190,7 @@ static struct tty_driver *hvc_console_device(struct console *c, int *index)
return hvc_driver;
}
static int __init hvc_console_setup(struct console *co, char *options)
static int hvc_console_setup(struct console *co, char *options)
{
if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES)
return -ENODEV;

4
drivers/tty/n_tty.c
View File

@ -2353,8 +2353,12 @@ static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
if (tty->ops->flush_chars)
tty->ops->flush_chars(tty);
} else {
struct n_tty_data *ldata = tty->disc_data;
while (nr > 0) {
mutex_lock(&ldata->output_lock);
c = tty->ops->write(tty, b, nr);
mutex_unlock(&ldata->output_lock);
if (c < 0) {
retval = c;
goto break_out;

2
drivers/tty/serial/8250/8250_core.c
View File

@ -555,7 +555,7 @@ static void serial8250_set_sleep(struct uart_8250_port *p, int sleep)
*/
if ((p->port.type == PORT_XR17V35X) ||
(p->port.type == PORT_XR17D15X)) {
serial_out(p, UART_EXAR_SLEEP, 0xff);
serial_out(p, UART_EXAR_SLEEP, sleep ? 0xff : 0);
return;
}

29
drivers/tty/tty_buffer.c
View File

@ -255,16 +255,15 @@ static int __tty_buffer_request_room(struct tty_port *port, size_t size,
if (change || left < size) {
/* This is the slow path - looking for new buffers to use */
if ((n = tty_buffer_alloc(port, size)) != NULL) {
unsigned long iflags;
n->flags = flags;
buf->tail = n;
spin_lock_irqsave(&buf->flush_lock, iflags);
b->commit = b->used;
/* paired w/ barrier in flush_to_ldisc(); ensures the
* latest commit value can be read before the head is
* advanced to the next buffer
*/
smp_wmb();
b->next = n;
spin_unlock_irqrestore(&buf->flush_lock, iflags);
} else if (change)
size = 0;
else
@ -448,27 +447,28 @@ static void flush_to_ldisc(struct work_struct *work)
mutex_lock(&buf->lock);
while (1) {
unsigned long flags;
struct tty_buffer *head = buf->head;
struct tty_buffer *next;
int count;
/* Ldisc or user is trying to gain exclusive access */
if (atomic_read(&buf->priority))
break;
spin_lock_irqsave(&buf->flush_lock, flags);
next = head->next;
/* paired w/ barrier in __tty_buffer_request_room();
* ensures commit value read is not stale if the head
* is advancing to the next buffer
*/
smp_rmb();
count = head->commit - head->read;
if (!count) {
if (head->next == NULL) {
spin_unlock_irqrestore(&buf->flush_lock, flags);
if (next == NULL)
break;
}
buf->head = head->next;
spin_unlock_irqrestore(&buf->flush_lock, flags);
buf->head = next;
tty_buffer_free(port, head);
continue;
}
spin_unlock_irqrestore(&buf->flush_lock, flags);
count = receive_buf(tty, head, count);
if (!count)
@ -523,7 +523,6 @@ void tty_buffer_init(struct tty_port *port)
struct tty_bufhead *buf = &port->buf;
mutex_init(&buf->lock);
spin_lock_init(&buf->flush_lock);
tty_buffer_reset(&buf->sentinel, 0);
buf->head = &buf->sentinel;
buf->tail = &buf->sentinel;

1
include/linux/tty.h
View File

@ -61,7 +61,6 @@ struct tty_bufhead {
struct tty_buffer *head; /* Queue head */
struct work_struct work;
struct mutex lock;
spinlock_t flush_lock;
atomic_t priority;
struct tty_buffer sentinel;
struct llist_head free; /* Free queue head */