diff options
Diffstat (limited to 'drivers/char/tty_buffer.c')
| -rw-r--r-- | drivers/char/tty_buffer.c | 524 |
1 files changed, 0 insertions, 524 deletions
diff --git a/drivers/char/tty_buffer.c b/drivers/char/tty_buffer.c deleted file mode 100644 index cc1e9850d65..00000000000 --- a/drivers/char/tty_buffer.c +++ /dev/null @@ -1,524 +0,0 @@ -/* - * Tty buffer allocation management - */ - -#include <linux/types.h> -#include <linux/errno.h> -#include <linux/tty.h> -#include <linux/tty_driver.h> -#include <linux/tty_flip.h> -#include <linux/timer.h> -#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> -#include <linux/module.h> - -/** - * tty_buffer_free_all - free buffers used by a tty - * @tty: tty to free from - * - * Remove all the buffers pending on a tty whether queued with data - * or in the free ring. Must be called when the tty is no longer in use - * - * Locking: none - */ - -void tty_buffer_free_all(struct tty_struct *tty) -{ - struct tty_buffer *thead; - while ((thead = tty->buf.head) != NULL) { - tty->buf.head = thead->next; - kfree(thead); - } - while ((thead = tty->buf.free) != NULL) { - tty->buf.free = thead->next; - kfree(thead); - } - tty->buf.tail = NULL; - tty->buf.memory_used = 0; -} - -/** - * tty_buffer_alloc - allocate a tty buffer - * @tty: tty device - * @size: desired size (characters) - * - * Allocate a new tty buffer to hold the desired number of characters. - * Return NULL if out of memory or the allocation would exceed the - * per device queue - * - * Locking: Caller must hold tty->buf.lock - */ - -static struct tty_buffer *tty_buffer_alloc(struct tty_struct *tty, size_t size) -{ - struct tty_buffer *p; - - if (tty->buf.memory_used + size > 65536) - return NULL; - p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC); - if (p == NULL) - return NULL; - p->used = 0; - p->size = 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; - tty->buf.memory_used += size; - return p; -} - -/** - * tty_buffer_free - free a tty buffer - * @tty: tty owning the buffer - * @b: the buffer to free - * - * Free a tty buffer, or add it to the free list according to our - * internal strategy - * - * Locking: Caller must hold tty->buf.lock - */ - -static void tty_buffer_free(struct tty_struct *tty, struct tty_buffer *b) -{ - /* Dumb strategy for now - should keep some stats */ - tty->buf.memory_used -= b->size; - WARN_ON(tty->buf.memory_used < 0); - - if (b->size >= 512) - kfree(b); - else { - b->next = tty->buf.free; - tty->buf.free = b; - } -} - -/** - * __tty_buffer_flush - flush full tty buffers - * @tty: tty to flush - * - * flush all the buffers containing receive data. Caller must - * hold the buffer lock and must have ensured no parallel flush to - * ldisc is running. - * - * Locking: Caller must hold tty->buf.lock - */ - -static void __tty_buffer_flush(struct tty_struct *tty) -{ - struct tty_buffer *thead; - - while ((thead = tty->buf.head) != NULL) { - tty->buf.head = thead->next; - tty_buffer_free(tty, thead); - } - tty->buf.tail = NULL; -} - -/** - * 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 - * - * Locking: none - */ - -void tty_buffer_flush(struct tty_struct *tty) -{ - unsigned long flags; - spin_lock_irqsave(&tty->buf.lock, flags); - - /* If the data is being pushed to the tty layer then we can't - process it here. Instead set a flag and the flush_to_ldisc - path will process the flush request before it exits */ - if (test_bit(TTY_FLUSHING, &tty->flags)) { - set_bit(TTY_FLUSHPENDING, &tty->flags); - spin_unlock_irqrestore(&tty->buf.lock, flags); - wait_event(tty->read_wait, - test_bit(TTY_FLUSHPENDING, &tty->flags) == 0); - return; - } else - __tty_buffer_flush(tty); - spin_unlock_irqrestore(&tty->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_struct *tty, size_t size) -{ - struct tty_buffer **tbh = &tty->buf.free; - while ((*tbh) != NULL) { - struct tty_buffer *t = *tbh; - if (t->size >= size) { - *tbh = t->next; - t->next = NULL; - t->used = 0; - t->commit = 0; - t->read = 0; - tty->buf.memory_used += t->size; - return t; - } - tbh = &((*tbh)->next); - } - /* Round the buffer size out */ - size = (size + 0xFF) & ~0xFF; - return tty_buffer_alloc(tty, 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 - * @size: size desired - * - * Make at least size bytes of linear space available for the tty - * buffer. If we fail return the size we managed to find. - * - * Locking: Takes tty->buf.lock - */ -int tty_buffer_request_room(struct tty_struct *tty, size_t size) -{ - struct tty_buffer *b, *n; - int left; - unsigned long flags; - - spin_lock_irqsave(&tty->buf.lock, flags); - - /* OPTIMISATION: We could keep a per tty "zero" sized buffer to - remove this conditional if its worth it. This would be invisible - to the callers */ - if ((b = tty->buf.tail) != NULL) - left = b->size - b->used; - else - left = 0; - - if (left < size) { - /* This is the slow path - looking for new buffers to use */ - if ((n = tty_buffer_find(tty, size)) != NULL) { - if (b != NULL) { - b->next = n; - b->commit = b->used; - } else - tty->buf.head = n; - tty->buf.tail = n; - } else - size = left; - } - - spin_unlock_irqrestore(&tty->buf.lock, flags); - return size; -} -EXPORT_SYMBOL_GPL(tty_buffer_request_room); - -/** - * tty_insert_flip_string_fixed_flag - Add characters to the tty buffer - * @tty: tty structure - * @chars: characters - * @flag: flag value for each character - * @size: size - * - * Queue a series of bytes to the tty buffering. All the characters - * passed are marked with the supplied flag. Returns the number added. - * - * Locking: Called functions may take tty->buf.lock - */ - -int tty_insert_flip_string_fixed_flag(struct tty_struct *tty, - const unsigned char *chars, char flag, size_t size) -{ - int copied = 0; - do { - int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE); - int space = tty_buffer_request_room(tty, goal); - struct tty_buffer *tb = tty->buf.tail; - /* If there is no space then tb may be NULL */ - if (unlikely(space == 0)) - break; - memcpy(tb->char_buf_ptr + tb->used, chars, space); - memset(tb->flag_buf_ptr + tb->used, flag, space); - tb->used += space; - copied += space; - chars += space; - /* There is a small chance that we need to split the data over - several buffers. If this is the case we must loop */ - } while (unlikely(size > copied)); - return copied; -} -EXPORT_SYMBOL(tty_insert_flip_string_fixed_flag); - -/** - * tty_insert_flip_string_flags - Add characters to the tty buffer - * @tty: tty structure - * @chars: characters - * @flags: flag bytes - * @size: size - * - * Queue a series of bytes to the tty buffering. For each character - * the flags array indicates the status of the character. Returns the - * number added. - * - * Locking: Called functions may take tty->buf.lock - */ - -int tty_insert_flip_string_flags(struct tty_struct *tty, - const unsigned char *chars, const char *flags, size_t size) -{ - int copied = 0; - do { - int goal = min_t(size_t, size - copied, TTY_BUFFER_PAGE); - int space = tty_buffer_request_room(tty, goal); - struct tty_buffer *tb = tty->buf.tail; - /* If there is no space then tb may be NULL */ - if (unlikely(space == 0)) - break; - memcpy(tb->char_buf_ptr + tb->used, chars, space); - memcpy(tb->flag_buf_ptr + tb->used, flags, space); - tb->used += space; - copied += space; - chars += space; - flags += space; - /* There is a small chance that we need to split the data over - several buffers. If this is the case we must loop */ - } while (unlikely(size > copied)); - return copied; -} -EXPORT_SYMBOL(tty_insert_flip_string_flags); - -/** - * tty_schedule_flip - push characters to ldisc - * @tty: tty to push from - * - * Takes any pending buffers and transfers their ownership to the - * ldisc side of the queue. It then schedules those characters for - * processing by the line discipline. - * - * Locking: Takes tty->buf.lock - */ - -void tty_schedule_flip(struct tty_struct *tty) -{ - unsigned long flags; - spin_lock_irqsave(&tty->buf.lock, flags); - if (tty->buf.tail != NULL) - tty->buf.tail->commit = tty->buf.tail->used; - spin_unlock_irqrestore(&tty->buf.lock, flags); - schedule_delayed_work(&tty->buf.work, 1); -} -EXPORT_SYMBOL(tty_schedule_flip); - -/** - * tty_prepare_flip_string - make room for characters - * @tty: tty - * @chars: return pointer for character 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 normal 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! - * - * Locking: May call functions taking tty->buf.lock - */ - -int tty_prepare_flip_string(struct tty_struct *tty, unsigned char **chars, - size_t size) -{ - int space = tty_buffer_request_room(tty, size); - if (likely(space)) { - struct tty_buffer *tb = tty->buf.tail; - *chars = tb->char_buf_ptr + tb->used; - memset(tb->flag_buf_ptr + 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 - * @tty: tty - * @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! - * - * Locking: May call functions taking tty->buf.lock - */ - -int tty_prepare_flip_string_flags(struct tty_struct *tty, - unsigned char **chars, char **flags, size_t size) -{ - int space = tty_buffer_request_room(tty, size); - if (likely(space)) { - struct tty_buffer *tb = tty->buf.tail; - *chars = tb->char_buf_ptr + tb->used; - *flags = tb->flag_buf_ptr + tb->used; - tb->used += space; - } - return space; -} -EXPORT_SYMBOL_GPL(tty_prepare_flip_string_flags); - - - -/** - * flush_to_ldisc - * @work: tty structure passed from work queue. - * - * This routine is called out of the software interrupt to flush data - * from the buffer chain to the line discipline. - * - * Locking: holds tty->buf.lock to guard buffer list. Drops the lock - * while invoking the line discipline receive_buf method. The - * receive_buf method is single threaded for each tty instance. - */ - -static void flush_to_ldisc(struct work_struct *work) -{ - struct tty_struct *tty = - container_of(work, struct tty_struct, buf.work.work); - unsigned long flags; - struct tty_ldisc *disc; - - disc = tty_ldisc_ref(tty); - if (disc == NULL) /* !TTY_LDISC */ - return; - - spin_lock_irqsave(&tty->buf.lock, flags); - - if (!test_and_set_bit(TTY_FLUSHING, &tty->flags)) { - struct tty_buffer *head; - while ((head = tty->buf.head) != NULL) { - int count; - char *char_buf; - unsigned char *flag_buf; - - count = head->commit - head->read; - if (!count) { - if (head->next == NULL) - break; - tty->buf.head = head->next; - tty_buffer_free(tty, head); - continue; - } - /* Ldisc or user is trying to flush the buffers - we are feeding to the ldisc, stop feeding the - line discipline as we want to empty the queue */ - if (test_bit(TTY_FLUSHPENDING, &tty->flags)) - break; - if (!tty->receive_room) { - schedule_delayed_work(&tty->buf.work, 1); - break; - } - if (count > tty->receive_room) - count = tty->receive_room; - char_buf = head->char_buf_ptr + head->read; - flag_buf = head->flag_buf_ptr + head->read; - head->read += count; - spin_unlock_irqrestore(&tty->buf.lock, flags); - disc->ops->receive_buf(tty, char_buf, - flag_buf, count); - spin_lock_irqsave(&tty->buf.lock, flags); - } - clear_bit(TTY_FLUSHING, &tty->flags); - } - - /* We may have a deferred request to flush the input buffer, - if so pull the chain under the lock and empty the queue */ - if (test_bit(TTY_FLUSHPENDING, &tty->flags)) { - __tty_buffer_flush(tty); - clear_bit(TTY_FLUSHPENDING, &tty->flags); - wake_up(&tty->read_wait); - } - spin_unlock_irqrestore(&tty->buf.lock, flags); - - tty_ldisc_deref(disc); -} - -/** - * tty_flush_to_ldisc - * @tty: tty to push - * - * Push the terminal flip buffers to the line discipline. - * - * Must not be called from IRQ context. - */ -void tty_flush_to_ldisc(struct tty_struct *tty) -{ - flush_delayed_work(&tty->buf.work); -} - -/** - * tty_flip_buffer_push - terminal - * @tty: tty to push - * - * Queue a push of the terminal flip buffers to the line discipline. This - * function must not be called from IRQ context if tty->low_latency is set. - * - * In the event of the queue being busy for flipping the work will be - * held off and retried later. - * - * Locking: tty buffer lock. Driver locks in low latency mode. - */ - -void tty_flip_buffer_push(struct tty_struct *tty) -{ - unsigned long flags; - spin_lock_irqsave(&tty->buf.lock, flags); - if (tty->buf.tail != NULL) - tty->buf.tail->commit = tty->buf.tail->used; - spin_unlock_irqrestore(&tty->buf.lock, flags); - - if (tty->low_latency) - flush_to_ldisc(&tty->buf.work.work); - else - schedule_delayed_work(&tty->buf.work, 1); -} -EXPORT_SYMBOL(tty_flip_buffer_push); - -/** - * tty_buffer_init - prepare a tty buffer structure - * @tty: tty to initialise - * - * Set up the initial state of the buffer management for a tty device. - * Must be called before the other tty buffer functions are used. - * - * Locking: none - */ - -void tty_buffer_init(struct tty_struct *tty) -{ - spin_lock_init(&tty->buf.lock); - tty->buf.head = NULL; - tty->buf.tail = NULL; - tty->buf.free = NULL; - tty->buf.memory_used = 0; - INIT_DELAYED_WORK(&tty->buf.work, flush_to_ldisc); -} - |