1 files changed, 42 insertions, 89 deletions

diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index 45d916198f78..bb119934e76c 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -16,6 +16,7 @@
 #include <linux/bitops.h>
 #include <linux/delay.h>
 #include <linux/module.h>
+#include <linux/ratelimit.h>
 
 /**
  *      tty_buffer_free_all             -       free buffers used by a tty
@@ -119,11 +120,14 @@ static void __tty_buffer_flush(struct tty_port *port)
         struct tty_bufhead *buf = &port->buf;
         struct tty_buffer *thead;
 
-        while ((thead = buf->head) != NULL) {
-                buf->head = thead->next;
-                tty_buffer_free(port, thead);
+        if (unlikely(buf->head == NULL))
+                return;
+        while ((thead = buf->head->next) != NULL) {
+                tty_buffer_free(port, buf->head);
+                buf->head = thead;
         }
-        buf->tail = NULL;
+        WARN_ON(buf->head != buf->tail);
+        buf->head->read = buf->head->commit;
 }
 
 /**
@@ -194,19 +198,22 @@ static struct tty_buffer *tty_buffer_find(struct tty_port *port, size_t size)
            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 port->buf.lock
  */
-static int __tty_buffer_request_room(struct tty_port *port, size_t size)
+int tty_buffer_request_room(struct tty_port *port, size_t size)
 {
         struct tty_bufhead *buf = &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 */
@@ -228,37 +235,14 @@ static int __tty_buffer_request_room(struct tty_port *port, size_t size)
                 } else
                         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);
 
 /**
  *      tty_insert_flip_string_fixed_flag - Add characters to the tty buffer
- *      @tty: tty structure
+ *      @port: tty port
  *      @chars: characters
  *      @flag: flag value for each character
  *      @size: size
@@ -269,29 +253,21 @@ EXPORT_SYMBOL_GPL(tty_buffer_request_room);
  *      Locking: Called functions may take port->buf.lock
  */
 
-int tty_insert_flip_string_fixed_flag(struct tty_struct *tty,
+int tty_insert_flip_string_fixed_flag(struct tty_port *port,
                 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(port, goal);
+                struct tty_buffer *tb = port->buf.tail;
                 /* If there is no space then tb may be NULL */
                 if (unlikely(space == 0)) {
-                        spin_unlock_irqrestore(&buf->lock, flags);
                         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
@@ -303,7 +279,7 @@ EXPORT_SYMBOL(tty_insert_flip_string_fixed_flag);
 
 /**
  *      tty_insert_flip_string_flags    -       Add characters to the tty buffer
- *      @tty: tty structure
+ *      @port: tty port
  *      @chars: characters
  *      @flags: flag bytes
  *      @size: size
@@ -315,29 +291,21 @@ EXPORT_SYMBOL(tty_insert_flip_string_fixed_flag);
  *      Locking: Called functions may take port->buf.lock
  */
 
-int tty_insert_flip_string_flags(struct tty_struct *tty,
+int tty_insert_flip_string_flags(struct tty_port *port,
                 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(port, goal);
+                struct tty_buffer *tb = port->buf.tail;
                 /* If there is no space then tb may be NULL */
                 if (unlikely(space == 0)) {
-                        spin_unlock_irqrestore(&buf->lock, __flags);
                         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;
@@ -350,7 +318,7 @@ EXPORT_SYMBOL(tty_insert_flip_string_flags);
 
 /**
  *      tty_schedule_flip       -       push characters to ldisc
- *      @tty: tty to push from
+ *      @port: tty port to push from
  *
  *      Takes any pending buffers and transfers their ownership to the
  *      ldisc side of the queue. It then schedules those characters for
@@ -361,11 +329,11 @@ EXPORT_SYMBOL(tty_insert_flip_string_flags);
  *      Locking: Takes port->buf.lock
  */
 
-void tty_schedule_flip(struct tty_struct *tty)
+void tty_schedule_flip(struct tty_port *port)
 {
-        struct tty_bufhead *buf = &tty->port->buf;
+        struct tty_bufhead *buf = &port->buf;
         unsigned long flags;
-        WARN_ON(tty->low_latency);
+        WARN_ON(port->low_latency);
 
         spin_lock_irqsave(&buf->lock, flags);
         if (buf->tail != NULL)
@@ -377,7 +345,7 @@ EXPORT_SYMBOL(tty_schedule_flip);
 
 /**
  *      tty_prepare_flip_string         -       make room for characters
- *      @tty: tty
+ *      @port: tty port
  *      @chars: return pointer for character write area
  *      @size: desired size
  *
@@ -390,31 +358,23 @@ EXPORT_SYMBOL(tty_schedule_flip);
  *      Locking: May call functions taking port->buf.lock
  */
 
-int tty_prepare_flip_string(struct tty_struct *tty, unsigned char **chars,
+int tty_prepare_flip_string(struct tty_port *port, 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(port, size);
         if (likely(space)) {
+                struct tty_buffer *tb = 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);
 
 /**
  *      tty_prepare_flip_string_flags   -       make room for characters
- *      @tty: tty
+ *      @port: tty port
  *      @chars: return pointer for character write area
  *      @flags: return pointer for status flag write area
  *      @size: desired size
@@ -428,24 +388,16 @@ EXPORT_SYMBOL_GPL(tty_prepare_flip_string);
  *      Locking: May call functions taking port->buf.lock
  */
 
-int tty_prepare_flip_string_flags(struct tty_struct *tty,
+int tty_prepare_flip_string_flags(struct tty_port *port,
                         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(port, size);
         if (likely(space)) {
+                struct tty_buffer *tb = 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);
@@ -539,16 +491,17 @@ static void flush_to_ldisc(struct work_struct *work)
  */
 void tty_flush_to_ldisc(struct tty_struct *tty)
 {
-        if (!tty->low_latency)
+        if (!tty->port->low_latency)
                 flush_work(&tty->port->buf.work);
 }
 
 /**
  *      tty_flip_buffer_push    -       terminal
- *      @tty: tty to push
+ *      @port: tty port to push
  *
  *      Queue a push of the terminal flip buffers to the line discipline. This
- *      function must not be called from IRQ context if tty->low_latency is set.
+ *      function must not be called from IRQ context if port->low_latency is
+ *      set.
  *
  *      In the event of the queue being busy for flipping the work will be
  *      held off and retried later.
@@ -556,9 +509,9 @@ void tty_flush_to_ldisc(struct tty_struct *tty)
  *      Locking: tty buffer lock. Driver locks in low latency mode.
  */
 
-void tty_flip_buffer_push(struct tty_struct *tty)
+void tty_flip_buffer_push(struct tty_port *port)
 {
-        struct tty_bufhead *buf = &tty->port->buf;
+        struct tty_bufhead *buf = &port->buf;
         unsigned long flags;
 
         spin_lock_irqsave(&buf->lock, flags);
@@ -566,7 +519,7 @@ void tty_flip_buffer_push(struct tty_struct *tty)
                 buf->tail->commit = buf->tail->used;
         spin_unlock_irqrestore(&buf->lock, flags);
 
-        if (tty->low_latency)
+        if (port->low_latency)
                 flush_to_ldisc(&buf->work);
         else
                 schedule_work(&buf->work);