Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 11b9faa4 authored by Peter Hurley's avatar Peter Hurley Committed by Greg Kroah-Hartman
Browse files

tty: Merge tty_buffer_find() into tty_buffer_alloc() 



tty_buffer_find() implements a simple free list lookaside cache.
Merge this functionality into tty_buffer_alloc() to reflect the
more traditional alloc/free symmetry.

Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 9dd5139f

drivers/tty/tty_buffer.c

+18 −32
Original line number Diff line number Diff line
@@ -64,6 +64,8 @@ void tty_buffer_free_all(struct tty_port *port) 
 *	@size: desired size (characters)

 *

 *	Allocate a new tty buffer to hold the desired number of characters.

 *	We round our buffers off in 256 character chunks to get better

 *	allocation behaviour.

 *	Return NULL if out of memory or the allocation would exceed the

 *	per device queue

 *
@@ -72,14 +74,29 @@ void tty_buffer_free_all(struct tty_port *port) 


static struct tty_buffer *tty_buffer_alloc(struct tty_port *port, size_t size)

{

	struct tty_buffer **tbh = &port->buf.free;

	struct tty_buffer *p;



	/* Round the buffer size out */

	size = __ALIGN_MASK(size, TTYB_ALIGN_MASK);



	if (size <= MIN_TTYB_SIZE) {

		if (*tbh) {

			p = *tbh;

			*tbh = p->next;

			goto found;

		}

	}



	/* Should possibly check if this fails for the largest buffer we

	   have queued and recycle that ? */

	if (port->buf.memory_used + size > 65536)

		return NULL;

	p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC);

	if (p == NULL)

		return NULL;



found:

	tty_buffer_reset(p, size);

	port->buf.memory_used += size;

	return p;
@@ -171,37 +188,6 @@ void tty_buffer_flush(struct tty_struct *tty) 
	spin_unlock_irqrestore(&buf->lock, flags);

}



/**

 *	tty_buffer_find		-	find a free tty buffer

 *	@tty: tty owning the buffer

 *	@size: characters wanted

 *

 *	Locate an existing suitable tty buffer or if we are lacking one then

 *	allocate a new one. We round our buffers off in 256 character chunks

 *	to get better allocation behaviour.

 *

 *	Locking: Caller must hold tty->buf.lock

 */



static struct tty_buffer *tty_buffer_find(struct tty_port *port, size_t size)

{

	struct tty_buffer **tbh = &port->buf.free;

	if (size <= MIN_TTYB_SIZE) {

		if (*tbh) {

			struct tty_buffer *t = *tbh;



			*tbh = t->next;

			tty_buffer_reset(t, t->size);

			port->buf.memory_used += t->size;

			return t;

		}

	}

	/* Round the buffer size out */

	size = __ALIGN_MASK(size, TTYB_ALIGN_MASK);

	return tty_buffer_alloc(port, 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: tty structure
@@ -230,7 +216,7 @@ 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_alloc(port, size)) != NULL) {

			if (b != NULL) {

				b->next = n;

				b->commit = b->used;