From: Peter Hurley Date: Fri, 22 Nov 2013 18:06:08 +0000 (-0500) Subject: staging/fwserial: Rip out rx buffering X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=c4a8dab5806188fb2a752467b63a7fd19bcbf0ec;p=linux-beck.git staging/fwserial: Rip out rx buffering Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/staging/fwserial/fwserial.c b/drivers/staging/fwserial/fwserial.c index 62df009e5ac7..ed7806b8b1dc 100644 --- a/drivers/staging/fwserial/fwserial.c +++ b/drivers/staging/fwserial/fwserial.c @@ -456,16 +456,27 @@ static int fwtty_write_port_status(struct fwtty_port *port) return err; } -static void __fwtty_throttle(struct fwtty_port *port, struct tty_struct *tty) +static void fwtty_throttle_port(struct fwtty_port *port) { + struct tty_struct *tty; unsigned old; + tty = tty_port_tty_get(&port->port); + if (!tty) + return; + + spin_lock_bh(&port->lock); + old = port->mctrl; port->mctrl |= OOB_RX_THROTTLE; if (C_CRTSCTS(tty)) port->mctrl &= ~TIOCM_RTS; if (~old & OOB_RX_THROTTLE) __fwtty_write_port_status(port); + + spin_unlock_bh(&port->lock); + + tty_kref_put(tty); } /** @@ -532,74 +543,8 @@ static void fwtty_emit_breaks(struct work_struct *work) port->icount.brk += brk; } -static void fwtty_pushrx(struct work_struct *work) -{ - struct fwtty_port *port = to_port(work, push); - struct tty_struct *tty; - struct buffered_rx *buf, *next; - int n, c = 0; - - spin_lock_bh(&port->lock); - list_for_each_entry_safe(buf, next, &port->buf_list, list) { - n = tty_insert_flip_string_fixed_flag(&port->port, buf->data, - TTY_NORMAL, buf->n); - c += n; - port->buffered -= n; - if (n < buf->n) { - if (n > 0) { - memmove(buf->data, buf->data + n, buf->n - n); - buf->n -= n; - } - tty = tty_port_tty_get(&port->port); - if (tty) { - __fwtty_throttle(port, tty); - tty_kref_put(tty); - } - break; - } else { - list_del(&buf->list); - kfree(buf); - } - } - if (c > 0) - tty_flip_buffer_push(&port->port); - - if (list_empty(&port->buf_list)) - clear_bit(BUFFERING_RX, &port->flags); - spin_unlock_bh(&port->lock); -} - -static int fwtty_buffer_rx(struct fwtty_port *port, unsigned char *d, size_t n) -{ - struct buffered_rx *buf; - size_t size = (n + sizeof(struct buffered_rx) + 0xFF) & ~0xFF; - - if (port->buffered + n > HIGH_WATERMARK) { - fwtty_err_ratelimited(port, "overflowed rx buffer: buffered: %d new: %zu wtrmk: %d\n", - port->buffered, n, HIGH_WATERMARK); - return 0; - } - buf = kmalloc(size, GFP_ATOMIC); - if (!buf) - return 0; - INIT_LIST_HEAD(&buf->list); - buf->n = n; - memcpy(buf->data, d, n); - - spin_lock_bh(&port->lock); - list_add_tail(&buf->list, &port->buf_list); - port->buffered += n; - if (port->buffered > port->stats.watermark) - port->stats.watermark = port->buffered; - set_bit(BUFFERING_RX, &port->flags); - spin_unlock_bh(&port->lock); - - return n; -} - static int fwtty_rx(struct fwtty_port *port, unsigned char *data, size_t len) { - struct tty_struct *tty; int c, n = len; unsigned lsr; int err = 0; @@ -636,31 +581,24 @@ static int fwtty_rx(struct fwtty_port *port, unsigned char *data, size_t len) goto out; } - if (!test_bit(BUFFERING_RX, &port->flags)) { - c = tty_insert_flip_string_fixed_flag(&port->port, data, - TTY_NORMAL, n); - if (c > 0) - tty_flip_buffer_push(&port->port); - n -= c; - - if (n) { - /* start buffering and throttling */ - n -= fwtty_buffer_rx(port, &data[c], n); - - tty = tty_port_tty_get(&port->port); - if (tty) { - spin_lock_bh(&port->lock); - __fwtty_throttle(port, tty); - spin_unlock_bh(&port->lock); - tty_kref_put(tty); - } - } - } else - n -= fwtty_buffer_rx(port, data, n); + c = tty_insert_flip_string_fixed_flag(&port->port, data, TTY_NORMAL, n); + if (c > 0) + tty_flip_buffer_push(&port->port); + n -= c; if (n) { port->overrun = true; err = -EIO; + fwtty_err_ratelimited(port, "flip buffer overrun\n"); + + } else { + /* throttle the sender if remaining flip buffer space has + * reached high watermark to avoid losing data which may be + * in-flight. Since the AR request context is 32k, that much + * data may have _already_ been acked. + */ + if (tty_buffer_space_avail(&port->port) < HIGH_WATERMARK) + fwtty_throttle_port(port); } out: @@ -1101,20 +1039,13 @@ static int fwtty_port_activate(struct tty_port *tty_port, static void fwtty_port_shutdown(struct tty_port *tty_port) { struct fwtty_port *port = to_port(tty_port, port); - struct buffered_rx *buf, *next; /* TODO: cancel outstanding transactions */ cancel_delayed_work_sync(&port->emit_breaks); cancel_delayed_work_sync(&port->drain); - cancel_work_sync(&port->push); spin_lock_bh(&port->lock); - list_for_each_entry_safe(buf, next, &port->buf_list, list) { - list_del(&buf->list); - kfree(buf); - } - port->buffered = 0; port->flags = 0; port->break_ctl = 0; port->overrun = 0; @@ -1264,8 +1195,6 @@ static void fwtty_unthrottle(struct tty_struct *tty) profile_fifo_avail(port, port->stats.unthrottle); - schedule_work(&port->push); - spin_lock_bh(&port->lock); port->mctrl &= ~OOB_RX_THROTTLE; if (C_CRTSCTS(tty)) @@ -1523,8 +1452,7 @@ static void fwtty_debugfs_show_port(struct seq_file *m, struct fwtty_port *port) seq_printf(m, " dr:%d st:%d err:%d lost:%d", stats.dropped, stats.tx_stall, stats.fifo_errs, stats.lost); - seq_printf(m, " pkts:%d thr:%d wtrmk:%d", stats.sent, stats.throttled, - stats.watermark); + seq_printf(m, " pkts:%d thr:%d", stats.sent, stats.throttled); if (port->port.console) { seq_puts(m, "\n "); @@ -2302,8 +2230,6 @@ static int fwserial_create(struct fw_unit *unit) INIT_DELAYED_WORK(&port->drain, fwtty_drain_tx); INIT_DELAYED_WORK(&port->emit_breaks, fwtty_emit_breaks); INIT_WORK(&port->hangup, fwtty_do_hangup); - INIT_WORK(&port->push, fwtty_pushrx); - INIT_LIST_HEAD(&port->buf_list); init_waitqueue_head(&port->wait_tx); port->max_payload = link_speed_to_max_payload(SCODE_100); dma_fifo_init(&port->tx_fifo); diff --git a/drivers/staging/fwserial/fwserial.h b/drivers/staging/fwserial/fwserial.h index 24635014a2ac..149b24dd0ba6 100644 --- a/drivers/staging/fwserial/fwserial.h +++ b/drivers/staging/fwserial/fwserial.h @@ -166,7 +166,6 @@ struct stats { unsigned sent; unsigned lost; unsigned throttled; - unsigned watermark; unsigned reads[DISTRIBUTION_MAX_INDEX + 1]; unsigned writes[DISTRIBUTION_MAX_INDEX + 1]; unsigned txns[DISTRIBUTION_MAX_INDEX + 1]; @@ -183,12 +182,6 @@ struct fwconsole_ops { #define FWCON_NOTIFY_ATTACH 1 #define FWCON_NOTIFY_DETACH 2 -struct buffered_rx { - struct list_head list; - size_t n; - unsigned char data[0]; -}; - /** * fwtty_port: structure used to track/represent underlying tty_port * @port: underlying tty_port @@ -223,11 +216,6 @@ struct buffered_rx { * The work can race with the writer but concurrent sending is * prevented with the IN_TX flag. Scheduled under lock to * limit scheduling when fifo has just been drained. - * @push: work responsible for pushing buffered rx to the ldisc. - * rx can become buffered if the tty buffer is filled before the - * ldisc throttles the sender. - * @buf_list: list of buffered rx yet to be sent to ldisc - * @buffered: byte count of buffered rx * @tx_fifo: fifo used to store & block-up writes for dma to remote * @max_payload: max bytes transmissable per dma (based on peer's max_payload) * @status_mask: UART_LSR_* bitmask significant to rx (based on termios) @@ -267,9 +255,6 @@ struct fwtty_port { spinlock_t lock; unsigned mctrl; struct delayed_work drain; - struct work_struct push; - struct list_head buf_list; - int buffered; struct dma_fifo tx_fifo; int max_payload; unsigned status_mask; @@ -291,7 +276,6 @@ struct fwtty_port { /* bit #s for flags field */ #define IN_TX 0 #define STOP_TX 1 -#define BUFFERING_RX 2 /* bitmasks for special mctrl/mstatus bits */ #define OOB_RX_THROTTLE 0x00010000 diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c index 6a3620e1cc7a..6454c0a747ef 100644 --- a/drivers/tty/tty_buffer.c +++ b/drivers/tty/tty_buffer.c @@ -92,6 +92,7 @@ int tty_buffer_space_avail(struct tty_port *port) 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) {