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Subject[PATCH -next 1/2] tty: Correct tty buffer flush.
Revert: tty: hold lock across tty buffer finding and buffer filling

Signed-off-by: Ilya Zykov <ilya@ilyx.ru>
---
drivers/tty/tty_buffer.c | 94 +++++++++++-----------------------------------
1 files changed, 22 insertions(+), 72 deletions(-)

diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index 45d9161..7602df8 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -193,20 +193,26 @@ static struct tty_buffer *tty_buffer_find(struct tty_port *port, size_t size)
/* Should possibly check if this fails for the largest buffer we
have queued and recycle that ? */
}
+
/**
- * __tty_buffer_request_room - grow tty buffer if needed
+ * tty_buffer_request_room - grow tty buffer if needed
* @tty: tty structure
* @size: size desired
*
* Make at least size bytes of linear space available for the tty
* buffer. If we fail return the size we managed to find.
- * Locking: Caller must hold port->buf.lock
+ *
+ * Locking: Takes tty->port->buf.lock
*/
-static int __tty_buffer_request_room(struct tty_port *port, size_t size)
+int tty_buffer_request_room(struct tty_struct *tty, size_t size)
{
- struct tty_bufhead *buf = &port->buf;
+ struct tty_bufhead *buf = &tty->port->buf;
struct tty_buffer *b, *n;
int left;
+ unsigned long flags;
+
+ spin_lock_irqsave(&buf->lock, flags);
+
/* OPTIMISATION: We could keep a per tty "zero" sized buffer to
remove this conditional if its worth it. This would be invisible
to the callers */
@@ -218,7 +224,7 @@ static int __tty_buffer_request_room(struct tty_port *port, size_t size)

if (left < size) {
/* This is the slow path - looking for new buffers to use */
- if ((n = tty_buffer_find(port, size)) != NULL) {
+ if ((n = tty_buffer_find(tty->port, size)) != NULL) {
if (b != NULL) {
b->next = n;
b->commit = b->used;
@@ -229,31 +235,9 @@ static int __tty_buffer_request_room(struct tty_port *port, size_t size)
size = left;
}

+ spin_unlock_irqrestore(&buf->lock, flags);
return size;
}
-
-
-/**
- * tty_buffer_request_room - grow tty buffer if needed
- * @tty: tty structure
- * @size: size desired
- *
- * Make at least size bytes of linear space available for the tty
- * buffer. If we fail return the size we managed to find.
- *
- * Locking: Takes port->buf.lock
- */
-int tty_buffer_request_room(struct tty_struct *tty, size_t size)
-{
- struct tty_port *port = tty->port;
- unsigned long flags;
- int length;
-
- spin_lock_irqsave(&port->buf.lock, flags);
- length = __tty_buffer_request_room(port, size);
- spin_unlock_irqrestore(&port->buf.lock, flags);
- return length;
-}
EXPORT_SYMBOL_GPL(tty_buffer_request_room);

/**
@@ -272,26 +256,17 @@ EXPORT_SYMBOL_GPL(tty_buffer_request_room);
int tty_insert_flip_string_fixed_flag(struct tty_struct *tty,
const unsigned char *chars, char flag, size_t size)
{
- struct tty_bufhead *buf = &tty->port->buf;
int copied = 0;
do {
int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE);
- int space;
- unsigned long flags;
- struct tty_buffer *tb;
-
- spin_lock_irqsave(&buf->lock, flags);
- space = __tty_buffer_request_room(tty->port, goal);
- tb = buf->tail;
+ int space = tty_buffer_request_room(tty, goal);
+ struct tty_buffer *tb = tty->port->buf.tail;
/* If there is no space then tb may be NULL */
- if (unlikely(space == 0)) {
- spin_unlock_irqrestore(&buf->lock, flags);
+ if (unlikely(space == 0))
break;
- }
memcpy(tb->char_buf_ptr + tb->used, chars, space);
memset(tb->flag_buf_ptr + tb->used, flag, space);
tb->used += space;
- spin_unlock_irqrestore(&buf->lock, flags);
copied += space;
chars += space;
/* There is a small chance that we need to split the data over
@@ -318,26 +293,17 @@ EXPORT_SYMBOL(tty_insert_flip_string_fixed_flag);
int tty_insert_flip_string_flags(struct tty_struct *tty,
const unsigned char *chars, const char *flags, size_t size)
{
- struct tty_bufhead *buf = &tty->port->buf;
int copied = 0;
do {
int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE);
- int space;
- unsigned long __flags;
- struct tty_buffer *tb;
-
- spin_lock_irqsave(&buf->lock, __flags);
- space = __tty_buffer_request_room(tty->port, goal);
- tb = buf->tail;
+ int space = tty_buffer_request_room(tty, goal);
+ struct tty_buffer *tb = tty->port->buf.tail;
/* If there is no space then tb may be NULL */
- if (unlikely(space == 0)) {
- spin_unlock_irqrestore(&buf->lock, __flags);
+ if (unlikely(space == 0))
break;
- }
memcpy(tb->char_buf_ptr + tb->used, chars, space);
memcpy(tb->flag_buf_ptr + tb->used, flags, space);
tb->used += space;
- spin_unlock_irqrestore(&buf->lock, __flags);
copied += space;
chars += space;
flags += space;
@@ -393,21 +359,13 @@ EXPORT_SYMBOL(tty_schedule_flip);
int tty_prepare_flip_string(struct tty_struct *tty, unsigned char **chars,
size_t size)
{
- struct tty_bufhead *buf = &tty->port->buf;
- int space;
- unsigned long flags;
- struct tty_buffer *tb;
-
- spin_lock_irqsave(&buf->lock, flags);
- space = __tty_buffer_request_room(tty->port, size);
-
- tb = buf->tail;
+ int space = tty_buffer_request_room(tty, size);
if (likely(space)) {
+ struct tty_buffer *tb = tty->port->buf.tail;
*chars = tb->char_buf_ptr + tb->used;
memset(tb->flag_buf_ptr + tb->used, TTY_NORMAL, space);
tb->used += space;
}
- spin_unlock_irqrestore(&buf->lock, flags);
return space;
}
EXPORT_SYMBOL_GPL(tty_prepare_flip_string);
@@ -431,21 +389,13 @@ EXPORT_SYMBOL_GPL(tty_prepare_flip_string);
int tty_prepare_flip_string_flags(struct tty_struct *tty,
unsigned char **chars, char **flags, size_t size)
{
- struct tty_bufhead *buf = &tty->port->buf;
- int space;
- unsigned long __flags;
- struct tty_buffer *tb;
-
- spin_lock_irqsave(&buf->lock, __flags);
- space = __tty_buffer_request_room(tty->port, size);
-
- tb = buf->tail;
+ int space = tty_buffer_request_room(tty, size);
if (likely(space)) {
+ struct tty_buffer *tb = tty->port->buf.tail;
*chars = tb->char_buf_ptr + tb->used;
*flags = tb->flag_buf_ptr + tb->used;
tb->used += space;
}
- spin_unlock_irqrestore(&buf->lock, __flags);
return space;
}
EXPORT_SYMBOL_GPL(tty_prepare_flip_string_flags);

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