diff options
| -rw-r--r-- | drivers/tty/tty_buffer.c | 61 | ||||
| -rw-r--r-- | drivers/tty/vt/selection.c | 4 | ||||
| -rw-r--r-- | include/linux/tty.h | 4 | ||||
| -rw-r--r-- | include/linux/tty_flip.h | 3 |
4 files changed, 56 insertions, 16 deletions
diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c index dbe4a718e2dc..f22e116db105 100644 --- a/drivers/tty/tty_buffer.c +++ b/drivers/tty/tty_buffer.c @@ -30,6 +30,42 @@ /** + * tty_buffer_lock_exclusive - gain exclusive access to buffer + * tty_buffer_unlock_exclusive - release exclusive access + * + * @port - tty_port owning the flip buffer + * + * 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 + */ + +void tty_buffer_lock_exclusive(struct tty_port *port) +{ + struct tty_bufhead *buf = &port->buf; + + atomic_inc(&buf->priority); + mutex_lock(&buf->lock); +} + +void tty_buffer_unlock_exclusive(struct tty_port *port) +{ + struct tty_bufhead *buf = &port->buf; + int restart; + + restart = buf->head->commit != buf->head->read; + + atomic_dec(&buf->priority); + mutex_unlock(&buf->lock); + if (restart) + queue_work(system_unbound_wq, &buf->work); +} + +/** * tty_buffer_space_avail - return unused buffer space * @port - tty_port owning the flip buffer * @@ -158,7 +194,7 @@ static void tty_buffer_free(struct tty_port *port, struct tty_buffer *b) * being processed by flush_to_ldisc then we defer the processing * to that function * - * Locking: takes flush_mutex to ensure single-threaded flip buffer + * Locking: takes buffer lock to ensure single-threaded flip buffer * 'consumer' */ @@ -168,16 +204,16 @@ void tty_buffer_flush(struct tty_struct *tty) struct tty_bufhead *buf = &port->buf; struct tty_buffer *next; - buf->flushpending = 1; + atomic_inc(&buf->priority); - mutex_lock(&buf->flush_mutex); + mutex_lock(&buf->lock); while ((next = buf->head->next) != NULL) { tty_buffer_free(port, buf->head); buf->head = next; } buf->head->read = buf->head->commit; - buf->flushpending = 0; - mutex_unlock(&buf->flush_mutex); + atomic_dec(&buf->priority); + mutex_unlock(&buf->lock); } /** @@ -383,7 +419,7 @@ receive_buf(struct tty_struct *tty, struct tty_buffer *head, int count) * * The receive_buf method is single threaded for each tty instance. * - * Locking: takes flush_mutex to ensure single-threaded flip buffer + * Locking: takes buffer lock to ensure single-threaded flip buffer * 'consumer' */ @@ -402,14 +438,14 @@ static void flush_to_ldisc(struct work_struct *work) if (disc == NULL) return; - mutex_lock(&buf->flush_mutex); + mutex_lock(&buf->lock); while (1) { struct tty_buffer *head = buf->head; int count; - /* Ldisc or user is trying to flush the buffers. */ - if (buf->flushpending) + /* Ldisc or user is trying to gain exclusive access */ + if (atomic_read(&buf->priority)) break; count = head->commit - head->read; @@ -426,7 +462,7 @@ static void flush_to_ldisc(struct work_struct *work) break; } - mutex_unlock(&buf->flush_mutex); + mutex_unlock(&buf->lock); tty_ldisc_deref(disc); } @@ -482,13 +518,12 @@ void tty_buffer_init(struct tty_port *port) { struct tty_bufhead *buf = &port->buf; - mutex_init(&buf->flush_mutex); + mutex_init(&buf->lock); tty_buffer_reset(&buf->sentinel, 0); buf->head = &buf->sentinel; buf->tail = &buf->sentinel; init_llist_head(&buf->free); atomic_set(&buf->memory_used, 0); - buf->flushpending = 0; + atomic_set(&buf->priority, 0); INIT_WORK(&buf->work, flush_to_ldisc); } - diff --git a/drivers/tty/vt/selection.c b/drivers/tty/vt/selection.c index 2ca8d6b6514c..ea27804d87af 100644 --- a/drivers/tty/vt/selection.c +++ b/drivers/tty/vt/selection.c @@ -24,6 +24,7 @@ #include <linux/selection.h> #include <linux/tiocl.h> #include <linux/console.h> +#include <linux/tty_flip.h> /* Don't take this from <ctype.h>: 011-015 on the screen aren't spaces */ #define isspace(c) ((c) == ' ') @@ -346,8 +347,8 @@ int paste_selection(struct tty_struct *tty) console_unlock(); ld = tty_ldisc_ref_wait(tty); + tty_buffer_lock_exclusive(&vc->port); - /* FIXME: this is completely unsafe */ add_wait_queue(&vc->paste_wait, &wait); while (sel_buffer && sel_buffer_lth > pasted) { set_current_state(TASK_INTERRUPTIBLE); @@ -363,6 +364,7 @@ int paste_selection(struct tty_struct *tty) remove_wait_queue(&vc->paste_wait, &wait); __set_current_state(TASK_RUNNING); + tty_buffer_unlock_exclusive(&vc->port); tty_ldisc_deref(ld); return 0; } diff --git a/include/linux/tty.h b/include/linux/tty.h index 991575fe3451..7a9a3b0a6b5a 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -67,8 +67,8 @@ static inline char *flag_buf_ptr(struct tty_buffer *b, int ofs) struct tty_bufhead { struct tty_buffer *head; /* Queue head */ struct work_struct work; - struct mutex flush_mutex; - unsigned int flushpending:1; + struct mutex lock; + atomic_t priority; struct tty_buffer sentinel; struct llist_head free; /* Free queue head */ atomic_t memory_used; /* In-use buffers excluding free list */ diff --git a/include/linux/tty_flip.h b/include/linux/tty_flip.h index 6944ed2ce692..21ddd7d9ea1f 100644 --- a/include/linux/tty_flip.h +++ b/include/linux/tty_flip.h @@ -32,4 +32,7 @@ static inline int tty_insert_flip_string(struct tty_port *port, return tty_insert_flip_string_fixed_flag(port, chars, TTY_NORMAL, size); } +extern void tty_buffer_lock_exclusive(struct tty_port *port); +extern void tty_buffer_unlock_exclusive(struct tty_port *port); + #endif /* _LINUX_TTY_FLIP_H */ |