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[PATCH] new tty buffering locking fix

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Change locking in the new tty buffering facility from using tty->read_lock,
which is currently ignored by drivers and thus ineffective.  New locking
uses a new tty buffering specific lock enforced centrally in the tty
buffering code.

Two drivers (esp and cyclades) are updated to use the tty buffering
functions instead of accessing tty buffering internals directly.  This is
required for the new locking to work.

Minor checks for NULL buffers added to
tty_prepare_flip_string/tty_prepare_flip_string_flags

Signed-off-by: Paul Fulghum <paulkf@microgate.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Paul Fulghum
2006-02-03 03:04:41 -08:00
committed by Linus Torvalds
parent 546cfdf47f
commit 808249ceba
6 changed files with 68 additions and 33 deletions
Download Patch File Download Diff File Expand all files Collapse all files
include/linux/kbd_kern.h
+5
View File
@@ -151,6 +151,11 @@ extern unsigned int keymap_count;
static inline void con_schedule_flip(struct tty_struct *t)
{
unsigned long flags;
spin_lock_irqsave(&t->buf.lock, flags);
if (t->buf.tail != NULL)
t->buf.tail->active = 0;
spin_unlock_irqrestore(&t->buf.lock, flags);
schedule_work(&t->buf.work);
}
include/linux/tty.h
+2
View File
@@ -57,6 +57,7 @@ struct tty_buffer {
unsigned char *flag_buf_ptr;
int used;
int size;
int active;
/* Data points here */
unsigned long data[0];
};
@@ -64,6 +65,7 @@ struct tty_buffer {
struct tty_bufhead {
struct work_struct work;
struct semaphore pty_sem;
spinlock_t lock;
struct tty_buffer *head; /* Queue head */
struct tty_buffer *tail; /* Active buffer */
struct tty_buffer *free; /* Free queue head */
include/linux/tty_flip.h
+6 -1
View File
@@ -17,7 +17,7 @@ _INLINE_ int tty_insert_flip_char(struct tty_struct *tty,
unsigned char ch, char flag)
{
struct tty_buffer *tb = tty->buf.tail;
if (tb && tb->used < tb->size) {
if (tb && tb->active && tb->used < tb->size) {
tb->flag_buf_ptr[tb->used] = flag;
tb->char_buf_ptr[tb->used++] = ch;
return 1;
@@ -27,6 +27,11 @@ _INLINE_ int tty_insert_flip_char(struct tty_struct *tty,
_INLINE_ void tty_schedule_flip(struct tty_struct *tty)
{
unsigned long flags;
spin_lock_irqsave(&tty->buf.lock, flags);
if (tty->buf.tail != NULL)
tty->buf.tail->active = 0;
spin_unlock_irqrestore(&tty->buf.lock, flags);
schedule_delayed_work(&tty->buf.work, 1);
}