diff options
Diffstat (limited to 'drivers/tty/tty_buffer.c')
| -rw-r--r-- | drivers/tty/tty_buffer.c | 279 |
1 files changed, 131 insertions, 148 deletions
diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c index 6c7e65b1d9a1..646510476c30 100644 --- a/drivers/tty/tty_buffer.c +++ b/drivers/tty/tty_buffer.c @@ -39,20 +39,15 @@ #define TTY_BUFFER_PAGE (((PAGE_SIZE - sizeof(struct tty_buffer)) / 2) & ~0xFF) /** - * tty_buffer_lock_exclusive - gain exclusive access to buffer - * tty_buffer_unlock_exclusive - release exclusive access + * tty_buffer_lock_exclusive - gain exclusive access to buffer + * @port: tty port owning the flip buffer * - * @port: tty port owning the flip buffer + * Guarantees safe use of the &tty_ldisc_ops.receive_buf() method by excluding + * the buffer work and any pending flush from using the flip buffer. Data can + * continue to be added concurrently to the flip buffer from the driver side. * - * Guarantees safe use of the line discipline's receive_buf() method by - * excluding the buffer work and any pending flush from using the flip - * buffer. Data can continue to be added concurrently to the flip buffer - * from the driver side. - * - * On release, the buffer work is restarted if there is data in the - * flip buffer + * See also tty_buffer_unlock_exclusive(). */ - void tty_buffer_lock_exclusive(struct tty_port *port) { struct tty_bufhead *buf = &port->buf; @@ -62,6 +57,14 @@ void tty_buffer_lock_exclusive(struct tty_port *port) } EXPORT_SYMBOL_GPL(tty_buffer_lock_exclusive); +/** + * tty_buffer_unlock_exclusive - release exclusive access + * @port: tty port owning the flip buffer + * + * The buffer work is restarted if there is data in the flip buffer. + * + * See also tty_buffer_lock_exclusive(). + */ void tty_buffer_unlock_exclusive(struct tty_port *port) { struct tty_bufhead *buf = &port->buf; @@ -77,17 +80,16 @@ void tty_buffer_unlock_exclusive(struct tty_port *port) EXPORT_SYMBOL_GPL(tty_buffer_unlock_exclusive); /** - * tty_buffer_space_avail - return unused buffer space - * @port: tty port owning the flip buffer + * tty_buffer_space_avail - return unused buffer space + * @port: tty port owning the flip buffer * - * Returns the # of bytes which can be written by the driver without - * reaching the buffer limit. + * Returns: the # of bytes which can be written by the driver without reaching + * the buffer limit. * - * Note: this does not guarantee that memory is available to write - * the returned # of bytes (use tty_prepare_flip_string_xxx() to - * pre-allocate if memory guarantee is required). + * Note: this does not guarantee that memory is available to write the returned + * # of bytes (use tty_prepare_flip_string() to pre-allocate if memory + * guarantee is required). */ - unsigned int tty_buffer_space_avail(struct tty_port *port) { int space = port->buf.mem_limit - atomic_read(&port->buf.mem_used); @@ -107,13 +109,12 @@ static void tty_buffer_reset(struct tty_buffer *p, size_t size) } /** - * tty_buffer_free_all - free buffers used by a tty - * @port: tty port to free from + * tty_buffer_free_all - free buffers used by a tty + * @port: tty port 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 + * 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. */ - void tty_buffer_free_all(struct tty_port *port) { struct tty_bufhead *buf = &port->buf; @@ -142,17 +143,17 @@ void tty_buffer_free_all(struct tty_port *port) } /** - * tty_buffer_alloc - allocate a tty buffer - * @port: tty 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 + * tty_buffer_alloc - allocate a tty buffer + * @port: tty 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. + * + * Returns: %NULL if out of memory or the allocation would exceed the per + * device queue. */ - static struct tty_buffer *tty_buffer_alloc(struct tty_port *port, size_t size) { struct llist_node *free; @@ -185,14 +186,13 @@ found: } /** - * tty_buffer_free - free a tty buffer - * @port: tty port owning the buffer - * @b: the buffer to free + * tty_buffer_free - free a tty buffer + * @port: tty port owning the buffer + * @b: the buffer to free * - * Free a tty buffer, or add it to the free list according to our - * internal strategy + * Free a tty buffer, or add it to the free list according to our internal + * strategy. */ - static void tty_buffer_free(struct tty_port *port, struct tty_buffer *b) { struct tty_bufhead *buf = &port->buf; @@ -207,17 +207,15 @@ static void tty_buffer_free(struct tty_port *port, struct tty_buffer *b) } /** - * tty_buffer_flush - flush full tty buffers - * @tty: tty to flush - * @ld: optional ldisc ptr (must be referenced) + * tty_buffer_flush - flush full tty buffers + * @tty: tty to flush + * @ld: optional ldisc ptr (must be referenced) * - * flush all the buffers containing receive data. If ld != NULL, - * flush the ldisc input buffer. + * Flush all the buffers containing receive data. If @ld != %NULL, flush the + * ldisc input buffer. * - * Locking: takes buffer lock to ensure single-threaded flip buffer - * 'consumer' + * Locking: takes buffer lock to ensure single-threaded flip buffer 'consumer'. */ - void tty_buffer_flush(struct tty_struct *tty, struct tty_ldisc *ld) { struct tty_port *port = tty->port; @@ -244,17 +242,18 @@ void tty_buffer_flush(struct tty_struct *tty, struct tty_ldisc *ld) } /** - * __tty_buffer_request_room - grow tty buffer if needed - * @port: tty port - * @size: size desired - * @flags: buffer flags if new buffer allocated (default = 0) + * __tty_buffer_request_room - grow tty buffer if needed + * @port: tty port + * @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. * - * 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. * - * 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. + * Returns: the size we managed to find. */ static int __tty_buffer_request_room(struct tty_port *port, size_t size, int flags) @@ -300,16 +299,17 @@ int tty_buffer_request_room(struct tty_port *port, size_t size) EXPORT_SYMBOL_GPL(tty_buffer_request_room); /** - * tty_insert_flip_string_fixed_flag - Add characters to the tty buffer - * @port: tty port - * @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. + * tty_insert_flip_string_fixed_flag - add characters to the tty buffer + * @port: tty port + * @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. */ - int tty_insert_flip_string_fixed_flag(struct tty_port *port, const unsigned char *chars, char flag, size_t size) { @@ -338,17 +338,17 @@ int tty_insert_flip_string_fixed_flag(struct tty_port *port, EXPORT_SYMBOL(tty_insert_flip_string_fixed_flag); /** - * tty_insert_flip_string_flags - Add characters to the tty buffer - * @port: tty port - * @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. + * tty_insert_flip_string_flags - add characters to the tty buffer + * @port: tty port + * @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. */ - int tty_insert_flip_string_flags(struct tty_port *port, const unsigned char *chars, const char *flags, size_t size) { @@ -376,13 +376,13 @@ int tty_insert_flip_string_flags(struct tty_port *port, EXPORT_SYMBOL(tty_insert_flip_string_flags); /** - * __tty_insert_flip_char - Add one character to the tty buffer - * @port: tty port - * @ch: character - * @flag: flag byte + * __tty_insert_flip_char - add one character to the tty buffer + * @port: tty port + * @ch: character + * @flag: flag byte * - * Queue a single byte to the tty buffering, with an optional flag. - * This is the slow path of tty_insert_flip_char. + * Queue a single byte @ch to the tty buffering, with an optional flag. This is + * the slow path of tty_insert_flip_char(). */ int __tty_insert_flip_char(struct tty_port *port, unsigned char ch, char flag) { @@ -402,39 +402,19 @@ int __tty_insert_flip_char(struct tty_port *port, unsigned char ch, char flag) EXPORT_SYMBOL(__tty_insert_flip_char); /** - * tty_schedule_flip - push characters to ldisc - * @port: tty port to push from + * tty_prepare_flip_string - make room for characters + * @port: tty port + * @chars: return pointer for character write area + * @size: desired size * - * 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. - */ - -void tty_schedule_flip(struct tty_port *port) -{ - struct tty_bufhead *buf = &port->buf; - - /* paired w/ acquire in flush_to_ldisc(); ensures - * flush_to_ldisc() sees buffer data. - */ - smp_store_release(&buf->tail->commit, buf->tail->used); - queue_work(system_unbound_wq, &buf->work); -} -EXPORT_SYMBOL(tty_schedule_flip); - -/** - * tty_prepare_flip_string - make room for characters - * @port: tty port - * @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! + * Prepare a block of space in the buffer for data. + * + * 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! + * + * Returns: the length available and buffer pointer (@chars) to the space which + * is now allocated and accounted for as ready for normal characters. */ - int tty_prepare_flip_string(struct tty_port *port, unsigned char **chars, size_t size) { @@ -453,16 +433,16 @@ int tty_prepare_flip_string(struct tty_port *port, unsigned char **chars, EXPORT_SYMBOL_GPL(tty_prepare_flip_string); /** - * tty_ldisc_receive_buf - forward data to line discipline - * @ld: line discipline to process input - * @p: char buffer - * @f: TTY_* flags buffer - * @count: number of bytes to process + * tty_ldisc_receive_buf - forward data to line discipline + * @ld: line discipline to process input + * @p: char buffer + * @f: %TTY_NORMAL, %TTY_BREAK, etc. flags buffer + * @count: number of bytes to process * - * Callers other than flush_to_ldisc() need to exclude the kworker - * from concurrent use of the line discipline, see paste_selection(). + * Callers other than flush_to_ldisc() need to exclude the kworker from + * concurrent use of the line discipline, see paste_selection(). * - * Returns the number of bytes processed + * Returns: the number of bytes processed. */ int tty_ldisc_receive_buf(struct tty_ldisc *ld, const unsigned char *p, const char *f, int count) @@ -495,18 +475,16 @@ receive_buf(struct tty_port *port, struct tty_buffer *head, int count) } /** - * flush_to_ldisc - * @work: tty structure passed from work queue. + * flush_to_ldisc - flush data from buffer 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. + * This routine is called out of the software interrupt to flush data from the + * buffer chain to the line discipline. * - * The receive_buf method is single threaded for each tty instance. + * The receive_buf() method is single threaded for each tty instance. * - * Locking: takes buffer lock to ensure single-threaded flip buffer - * 'consumer' + * Locking: takes buffer lock to ensure single-threaded flip buffer 'consumer'. */ - static void flush_to_ldisc(struct work_struct *work) { struct tty_port *port = container_of(work, struct tty_port, buf.work); @@ -554,30 +532,35 @@ static void flush_to_ldisc(struct work_struct *work) } /** - * tty_flip_buffer_push - terminal - * @port: tty port to push + * tty_flip_buffer_push - push terminal buffers + * @port: tty port to push * - * Queue a push of the terminal flip buffers to the line discipline. - * Can be called from IRQ/atomic context. + * Queue a push of the terminal flip buffers to the line discipline. Can be + * called from IRQ/atomic context. * - * In the event of the queue being busy for flipping the work will be - * held off and retried later. + * In the event of the queue being busy for flipping the work will be held off + * and retried later. */ - void tty_flip_buffer_push(struct tty_port *port) { - tty_schedule_flip(port); + struct tty_bufhead *buf = &port->buf; + + /* + * Paired w/ acquire in flush_to_ldisc(); ensures flush_to_ldisc() sees + * buffer data. + */ + smp_store_release(&buf->tail->commit, buf->tail->used); + queue_work(system_unbound_wq, &buf->work); } EXPORT_SYMBOL(tty_flip_buffer_push); /** - * tty_buffer_init - prepare a tty buffer structure - * @port: tty port to initialise + * tty_buffer_init - prepare a tty buffer structure + * @port: tty port 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. + * Set up the initial state of the buffer management for a tty device. Must be + * called before the other tty buffer functions are used. */ - void tty_buffer_init(struct tty_port *port) { struct tty_bufhead *buf = &port->buf; @@ -594,14 +577,14 @@ void tty_buffer_init(struct tty_port *port) } /** - * tty_buffer_set_limit - change the tty buffer memory limit - * @port: tty port to change - * @limit: memory limit to set + * tty_buffer_set_limit - change the tty buffer memory limit + * @port: tty port to change + * @limit: memory limit to set * - * Change the tty buffer memory limit. - * Must be called before the other tty buffer functions are used. + * 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) |