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Diffstat (limited to 'drivers/tty/tty_buffer.c')
-rw-r--r--drivers/tty/tty_buffer.c111
1 files changed, 62 insertions, 49 deletions
diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index c043136fbe5..765125dff20 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -11,7 +11,6 @@
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/sched.h>
-#include <linux/init.h>
#include <linux/wait.h>
#include <linux/bitops.h>
#include <linux/delay.h>
@@ -26,7 +25,7 @@
* Byte threshold to limit memory consumption for flip buffers.
* The actual memory limit is > 2x this amount.
*/
-#define TTYB_MEM_LIMIT 65536
+#define TTYB_DEFAULT_MEM_LIMIT 65536
/*
* We default to dicing tty buffer allocations to this many characters
@@ -89,9 +88,10 @@ void tty_buffer_unlock_exclusive(struct tty_port *port)
int tty_buffer_space_avail(struct tty_port *port)
{
- int space = TTYB_MEM_LIMIT - atomic_read(&port->buf.memory_used);
+ int space = port->buf.mem_limit - atomic_read(&port->buf.mem_used);
return max(space, 0);
}
+EXPORT_SYMBOL_GPL(tty_buffer_space_avail);
static void tty_buffer_reset(struct tty_buffer *p, size_t size)
{
@@ -100,6 +100,7 @@ static void tty_buffer_reset(struct tty_buffer *p, size_t size)
p->next = NULL;
p->commit = 0;
p->read = 0;
+ p->flags = 0;
}
/**
@@ -129,7 +130,7 @@ void tty_buffer_free_all(struct tty_port *port)
buf->head = &buf->sentinel;
buf->tail = &buf->sentinel;
- atomic_set(&buf->memory_used, 0);
+ atomic_set(&buf->mem_used, 0);
}
/**
@@ -162,7 +163,7 @@ static struct tty_buffer *tty_buffer_alloc(struct tty_port *port, size_t size)
/* Should possibly check if this fails for the largest buffer we
have queued and recycle that ? */
- if (atomic_read(&port->buf.memory_used) > TTYB_MEM_LIMIT)
+ if (atomic_read(&port->buf.mem_used) > port->buf.mem_limit)
return NULL;
p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC);
if (p == NULL)
@@ -170,7 +171,7 @@ static struct tty_buffer *tty_buffer_alloc(struct tty_port *port, size_t size)
found:
tty_buffer_reset(p, size);
- atomic_add(size, &port->buf.memory_used);
+ atomic_add(size, &port->buf.mem_used);
return p;
}
@@ -188,7 +189,7 @@ static void tty_buffer_free(struct tty_port *port, struct tty_buffer *b)
struct tty_bufhead *buf = &port->buf;
/* Dumb strategy for now - should keep some stats */
- WARN_ON(atomic_sub_return(b->size, &buf->memory_used) < 0);
+ WARN_ON(atomic_sub_return(b->size, &buf->mem_used) < 0);
if (b->size > MIN_TTYB_SIZE)
kfree(b);
@@ -200,9 +201,7 @@ static void tty_buffer_free(struct tty_port *port, struct tty_buffer *b)
* tty_buffer_flush - flush full tty buffers
* @tty: tty to flush
*
- * flush all the buffers containing receive data. If the buffer is
- * being processed by flush_to_ldisc then we defer the processing
- * to that function
+ * flush all the buffers containing receive data.
*
* Locking: takes buffer lock to ensure single-threaded flip buffer
* 'consumer'
@@ -230,31 +229,49 @@ void tty_buffer_flush(struct tty_struct *tty)
* tty_buffer_request_room - grow tty buffer if needed
* @tty: tty structure
* @size: size desired
+ * @flags: buffer flags if new buffer allocated (default = 0)
*
* Make at least size bytes of linear space available for the tty
* buffer. If we fail return the size we managed to find.
+ *
+ * Will change over to a new buffer if the current buffer is encoded as
+ * TTY_NORMAL (so has no flags buffer) and the new buffer requires
+ * a flags buffer.
*/
-int tty_buffer_request_room(struct tty_port *port, size_t size)
+static int __tty_buffer_request_room(struct tty_port *port, size_t size,
+ int flags)
{
struct tty_bufhead *buf = &port->buf;
struct tty_buffer *b, *n;
- int left;
+ int left, change;
b = buf->tail;
- left = b->size - b->used;
+ if (b->flags & TTYB_NORMAL)
+ left = 2 * b->size - b->used;
+ else
+ left = b->size - b->used;
- if (left < size) {
+ change = (b->flags & TTYB_NORMAL) && (~flags & TTYB_NORMAL);
+ if (change || left < size) {
/* This is the slow path - looking for new buffers to use */
if ((n = tty_buffer_alloc(port, size)) != NULL) {
+ n->flags = flags;
buf->tail = n;
b->commit = b->used;
smp_mb();
b->next = n;
- } else
+ } else if (change)
+ size = 0;
+ else
size = left;
}
return size;
}
+
+int tty_buffer_request_room(struct tty_port *port, size_t size)
+{
+ return __tty_buffer_request_room(port, size, 0);
+}
EXPORT_SYMBOL_GPL(tty_buffer_request_room);
/**
@@ -274,12 +291,14 @@ int tty_insert_flip_string_fixed_flag(struct tty_port *port,
int copied = 0;
do {
int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE);
- int space = tty_buffer_request_room(port, goal);
+ int flags = (flag == TTY_NORMAL) ? TTYB_NORMAL : 0;
+ int space = __tty_buffer_request_room(port, goal, flags);
struct tty_buffer *tb = port->buf.tail;
if (unlikely(space == 0))
break;
memcpy(char_buf_ptr(tb, tb->used), chars, space);
- memset(flag_buf_ptr(tb, tb->used), flag, space);
+ if (~tb->flags & TTYB_NORMAL)
+ memset(flag_buf_ptr(tb, tb->used), flag, space);
tb->used += space;
copied += space;
chars += space;
@@ -362,52 +381,28 @@ EXPORT_SYMBOL(tty_schedule_flip);
int tty_prepare_flip_string(struct tty_port *port, unsigned char **chars,
size_t size)
{
- int space = tty_buffer_request_room(port, size);
+ int space = __tty_buffer_request_room(port, size, TTYB_NORMAL);
if (likely(space)) {
struct tty_buffer *tb = port->buf.tail;
*chars = char_buf_ptr(tb, tb->used);
- memset(flag_buf_ptr(tb, tb->used), TTY_NORMAL, space);
+ if (~tb->flags & TTYB_NORMAL)
+ memset(flag_buf_ptr(tb, tb->used), TTY_NORMAL, space);
tb->used += space;
}
return space;
}
EXPORT_SYMBOL_GPL(tty_prepare_flip_string);
-/**
- * tty_prepare_flip_string_flags - make room for characters
- * @port: tty port
- * @chars: return pointer for character write area
- * @flags: return pointer for status flag write area
- * @size: desired size
- *
- * Prepare a block of space in the buffer for data. Returns the length
- * available and buffer pointer to the space which is now allocated and
- * accounted for as ready for characters. This is used for drivers
- * that need their own block copy routines into the buffer. There is no
- * guarantee the buffer is a DMA target!
- */
-
-int tty_prepare_flip_string_flags(struct tty_port *port,
- unsigned char **chars, char **flags, size_t size)
-{
- int space = tty_buffer_request_room(port, size);
- if (likely(space)) {
- struct tty_buffer *tb = port->buf.tail;
- *chars = char_buf_ptr(tb, tb->used);
- *flags = flag_buf_ptr(tb, tb->used);
- tb->used += space;
- }
- return space;
-}
-EXPORT_SYMBOL_GPL(tty_prepare_flip_string_flags);
-
static int
receive_buf(struct tty_struct *tty, struct tty_buffer *head, int count)
{
struct tty_ldisc *disc = tty->ldisc;
unsigned char *p = char_buf_ptr(head, head->read);
- char *f = flag_buf_ptr(head, head->read);
+ char *f = NULL;
+
+ if (~head->flags & TTYB_NORMAL)
+ f = flag_buf_ptr(head, head->read);
if (disc->ops->receive_buf2)
count = disc->ops->receive_buf2(tty, p, f, count);
@@ -533,7 +528,25 @@ void tty_buffer_init(struct tty_port *port)
buf->head = &buf->sentinel;
buf->tail = &buf->sentinel;
init_llist_head(&buf->free);
- atomic_set(&buf->memory_used, 0);
+ atomic_set(&buf->mem_used, 0);
atomic_set(&buf->priority, 0);
INIT_WORK(&buf->work, flush_to_ldisc);
+ buf->mem_limit = TTYB_DEFAULT_MEM_LIMIT;
+}
+
+/**
+ * tty_buffer_set_limit - change the tty buffer memory limit
+ * @port: tty port to change
+ *
+ * Change the tty buffer memory limit.
+ * Must be called before the other tty buffer functions are used.
+ */
+
+int tty_buffer_set_limit(struct tty_port *port, int limit)
+{
+ if (limit < MIN_TTYB_SIZE)
+ return -EINVAL;
+ port->buf.mem_limit = limit;
+ return 0;
}
+EXPORT_SYMBOL_GPL(tty_buffer_set_limit);
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-12-15 20:51:26 +0000