tty: Fix flip buffer free list

Since flip buffers are size-aligned to 256 bytes and all flip
buffers 512-bytes or larger are not added to the free list, the
free list only contains 256-byte flip buffers.

Remove the list search when allocating a new flip buffer.

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

1 files changed, 10 insertions, 6 deletions

diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index 170674cb68fc..a5e396217f76 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -18,6 +18,10 @@
 #include <linux/module.h>
 #include <linux/ratelimit.h>
 
+
+#define MIN_TTYB_SIZE   256
+#define TTYB_ALIGN_MASK 255
+
 /**
  *      tty_buffer_free_all             -       free buffers used by a tty
  *      @tty: tty to free from
@@ -94,7 +98,7 @@ static void tty_buffer_free(struct tty_port *port, struct tty_buffer *b)
         buf->memory_used -= b->size;
         WARN_ON(buf->memory_used < 0);
 
-        if (b->size >= 512)
+        if (b->size > MIN_TTYB_SIZE)
                 kfree(b);
         else {
                 b->next = buf->free;
@@ -176,9 +180,10 @@ void tty_buffer_flush(struct tty_struct *tty)
 static struct tty_buffer *tty_buffer_find(struct tty_port *port, size_t size)
 {
         struct tty_buffer **tbh = &port->buf.free;
-        while ((*tbh) != NULL) {
-                struct tty_buffer *t = *tbh;
-                if (t->size >= size) {
+        if (size <= MIN_TTYB_SIZE) {
+                if (*tbh) {
+                        struct tty_buffer *t = *tbh;
+
                         *tbh = t->next;
                         t->next = NULL;
                         t->used = 0;
@@ -187,10 +192,9 @@ static struct tty_buffer *tty_buffer_find(struct tty_port *port, size_t size)
                         port->buf.memory_used += t->size;
                         return t;
                 }
-                tbh = &((*tbh)->next);
         }
         /* Round the buffer size out */
-        size = (size + 0xFF) & ~0xFF;
+        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 ? */