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Date: Fri, 22 Nov 2013 13:06:08 -0500
From: Peter Hurley <peter@...leysoftware.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Jiri Slaby <jslaby@...e.cz>, linux-serial@...r.kernel.org,
linux-kernel@...r.kernel.org,
Peter Hurley <peter@...leysoftware.com>
Subject: [PATCH staging-next 1/4] staging/fwserial: Rip out rx buffering
Signed-off-by: Peter Hurley <peter@...leysoftware.com>
---
drivers/staging/fwserial/fwserial.c | 128 ++++++++----------------------------
drivers/staging/fwserial/fwserial.h | 16 -----
drivers/tty/tty_buffer.c | 1 +
3 files changed, 28 insertions(+), 117 deletions(-)
diff --git a/drivers/staging/fwserial/fwserial.c b/drivers/staging/fwserial/fwserial.c
index ff92f34..c96f62e 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 2463501..149b24d 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 c4fe20e..0f2211f 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)
{
--
1.8.1.2
--
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