1 files changed, 65 insertions, 20 deletions

diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index 6c9b7cd6778a..91e326ffe7db 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -185,25 +185,19 @@ static struct tty_buffer *tty_buffer_find(struct tty_struct *tty, 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: Takes tty->buf.lock
+ *      Locking: Caller must hold tty->buf.lock
  */
-int tty_buffer_request_room(struct tty_struct *tty, size_t size)
+static int __tty_buffer_request_room(struct tty_struct *tty, size_t size)
 {
         struct tty_buffer *b, *n;
         int left;
-        unsigned long flags;
-
-        spin_lock_irqsave(&tty->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 */
@@ -225,9 +219,30 @@ int tty_buffer_request_room(struct tty_struct *tty, size_t size)
                         size = left;
         }
 
-        spin_unlock_irqrestore(&tty->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 tty->buf.lock
+ */
+int tty_buffer_request_room(struct tty_struct *tty, size_t size)
+{
+        unsigned long flags;
+        int length;
+
+        spin_lock_irqsave(&tty->buf.lock, flags);
+        length = __tty_buffer_request_room(tty, size);
+        spin_unlock_irqrestore(&tty->buf.lock, flags);
+        return length;
+}
 EXPORT_SYMBOL_GPL(tty_buffer_request_room);
 
 /**
@@ -249,14 +264,22 @@ int tty_insert_flip_string_fixed_flag(struct tty_struct *tty,
         int copied = 0;
         do {
                 int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE);
-                int space = tty_buffer_request_room(tty, goal);
-                struct tty_buffer *tb = tty->buf.tail;
+                int space;
+                unsigned long flags;
+                struct tty_buffer *tb;
+
+                spin_lock_irqsave(&tty->buf.lock, flags);
+                space = __tty_buffer_request_room(tty, goal);
+                tb = tty->buf.tail;
                 /* If there is no space then tb may be NULL */
-                if (unlikely(space == 0))
+                if (unlikely(space == 0)) {
+                        spin_unlock_irqrestore(&tty->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(&tty->buf.lock, flags);
                 copied += space;
                 chars += space;
                 /* There is a small chance that we need to split the data over
@@ -286,14 +309,22 @@ int tty_insert_flip_string_flags(struct tty_struct *tty,
         int copied = 0;
         do {
                 int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE);
-                int space = tty_buffer_request_room(tty, goal);
-                struct tty_buffer *tb = tty->buf.tail;
+                int space;
+                unsigned long __flags;
+                struct tty_buffer *tb;
+
+                spin_lock_irqsave(&tty->buf.lock, __flags);
+                space = __tty_buffer_request_room(tty, goal);
+                tb = tty->buf.tail;
                 /* If there is no space then tb may be NULL */
-                if (unlikely(space == 0))
+                if (unlikely(space == 0)) {
+                        spin_unlock_irqrestore(&tty->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(&tty->buf.lock, __flags);
                 copied += space;
                 chars += space;
                 flags += space;
@@ -344,13 +375,20 @@ EXPORT_SYMBOL(tty_schedule_flip);
 int tty_prepare_flip_string(struct tty_struct *tty, unsigned char **chars,
                                                                 size_t size)
 {
-        int space = tty_buffer_request_room(tty, size);
+        int space;
+        unsigned long flags;
+        struct tty_buffer *tb;
+
+        spin_lock_irqsave(&tty->buf.lock, flags);
+        space = __tty_buffer_request_room(tty, size);
+
+        tb = tty->buf.tail;
         if (likely(space)) {
-                struct tty_buffer *tb = tty->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(&tty->buf.lock, flags);
         return space;
 }
 EXPORT_SYMBOL_GPL(tty_prepare_flip_string);
@@ -374,13 +412,20 @@ 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)
 {
-        int space = tty_buffer_request_room(tty, size);
+        int space;
+        unsigned long __flags;
+        struct tty_buffer *tb;
+
+        spin_lock_irqsave(&tty->buf.lock, __flags);
+        space = __tty_buffer_request_room(tty, size);
+
+        tb = tty->buf.tail;
         if (likely(space)) {
-                struct tty_buffer *tb = tty->buf.tail;
                 *chars = tb->char_buf_ptr + tb->used;
                 *flags = tb->flag_buf_ptr + tb->used;
                 tb->used += space;
         }
+        spin_unlock_irqrestore(&tty->buf.lock, __flags);
         return space;
 }
 EXPORT_SYMBOL_GPL(tty_prepare_flip_string_flags);