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Commit 1fc359fc authored by Peter Hurley's avatar Peter Hurley Committed by Greg Kroah-Hartman
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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: default avatarPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent f0f947c1

drivers/tty/tty_buffer.c

+10 −12
Original line number Diff line number Diff line
@@ -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);

include/linux/tty.h

+10 −2
Original line number Diff line number Diff line
@@ -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

include/linux/tty_flip.h

+2 −2
Original line number Diff line number Diff line
@@ -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);