tty: Compute flip buffer ptrs

The char_buf_ptr and flag_buf_ptr values are trivially derived from
the .data field offset; compute values as needed.

Fixes a long-standing type-mismatch with the char and flag ptrs.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 22 insertions, 16 deletions

diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index ff1b2e37c3ca..170674cb68fc 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -71,8 +71,6 @@ static struct tty_buffer *tty_buffer_alloc(struct tty_port *port, size_t size)
         p->next = NULL;
         p->commit = 0;
         p->read = 0;
-        p->char_buf_ptr = (char *)(p->data);
-        p->flag_buf_ptr = (unsigned char *)p->char_buf_ptr + size;
         port->buf.memory_used += size;
         return p;
 }
@@ -265,8 +263,8 @@ int tty_insert_flip_string_fixed_flag(struct tty_port *port,
                 if (unlikely(space == 0)) {
                         break;
                 }
-                memcpy(tb->char_buf_ptr + tb->used, chars, space);
-                memset(tb->flag_buf_ptr + tb->used, flag, space);
+                memcpy(char_buf_ptr(tb, tb->used), chars, space);
+                memset(flag_buf_ptr(tb, tb->used), flag, space);
                 tb->used += space;
                 copied += space;
                 chars += space;
@@ -303,8 +301,8 @@ int tty_insert_flip_string_flags(struct tty_port *port,
                 if (unlikely(space == 0)) {
                         break;
                 }
-                memcpy(tb->char_buf_ptr + tb->used, chars, space);
-                memcpy(tb->flag_buf_ptr + tb->used, flags, space);
+                memcpy(char_buf_ptr(tb, tb->used), chars, space);
+                memcpy(flag_buf_ptr(tb, tb->used), flags, space);
                 tb->used += space;
                 copied += space;
                 chars += space;
@@ -364,8 +362,8 @@ int tty_prepare_flip_string(struct tty_port *port, unsigned char **chars,
         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);
+                *chars = char_buf_ptr(tb, tb->used);
+                memset(flag_buf_ptr(tb, tb->used), TTY_NORMAL, space);
                 tb->used += space;
         }
         return space;
@@ -394,8 +392,8 @@ int tty_prepare_flip_string_flags(struct tty_port *port,
         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;
+                *chars = char_buf_ptr(tb, tb->used);
+                *flags = flag_buf_ptr(tb, tb->used);
                 tb->used += space;
         }
         return space;
@@ -407,8 +405,8 @@ static int
 receive_buf(struct tty_struct *tty, struct tty_buffer *head, int count)
 {
         struct tty_ldisc *disc = tty->ldisc;
-        char          *p = head->char_buf_ptr + head->read;
-        unsigned char *f = head->flag_buf_ptr + head->read;
+        unsigned char *p = char_buf_ptr(head, head->read);
+        char          *f = flag_buf_ptr(head, head->read);
 
         if (disc->ops->receive_buf2)
                 count = disc->ops->receive_buf2(tty, p, f, count);
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 57a70d1d0412..87bbaa31ebf5 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -31,8 +31,6 @@
 
 struct tty_buffer {
         struct tty_buffer *next;
-        char *char_buf_ptr;
-        unsigned char *flag_buf_ptr;
         int used;
         int size;
         int commit;
@@ -41,6 +39,16 @@ struct tty_buffer {
         unsigned long data[0];
 };
 
+static inline unsigned char *char_buf_ptr(struct tty_buffer *b, int ofs)
+{
+        return ((unsigned char *)b->data) + ofs;
+}
+
+static inline char *flag_buf_ptr(struct tty_buffer *b, int ofs)
+{
+        return (char *)char_buf_ptr(b, ofs) + b->size;
+}
+
 /*
  * We default to dicing tty buffer allocations to this many characters
  * in order to avoid multiple page allocations. We know the size of
diff --git a/include/linux/tty_flip.h b/include/linux/tty_flip.h
index e0f252633b47..ad0303994c32 100644
--- a/include/linux/tty_flip.h
+++ b/include/linux/tty_flip.h
@@ -18,8 +18,8 @@ static inline int tty_insert_flip_char(struct tty_port *port,
 {
         struct tty_buffer *tb = port->buf.tail;
         if (tb && tb->used < tb->size) {
-                tb->flag_buf_ptr[tb->used] = flag;
-                tb->char_buf_ptr[tb->used++] = ch;
+                *flag_buf_ptr(tb, tb->used) = flag;
+                *char_buf_ptr(tb, tb->used++) = ch;
                 return 1;
         }
         return tty_insert_flip_string_flags(port, &ch, &flag, 1);