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TTY: hvsi, sanitize uses of tty
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- use tty, not hp->tty wherever possible
- pass tty down to some functions and go to step one
- do not defer tty_hangup calls -- it is as simple as schedule_work,
  so might be called with hp->lock held
- do not defer tty buffer flips -- since the driver does not use
  low_latency (it cannot actually), the flip is a simple tail move
  plus schedule_work. It will make our life easier in the next patch.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Jiri Slaby authored and Greg Kroah-Hartman committed Apr 9, 2012
1 parent d73a4e7 commit 28c0447
Showing 1 changed file with 30 additions and 58 deletions.
88 changes: 30 additions & 58 deletions drivers/tty/hvc/hvsi.c
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Original file line number Diff line number Diff line change
Expand Up @@ -237,7 +237,7 @@ static int hvsi_read(struct hvsi_struct *hp, char *buf, int count)
}

static void hvsi_recv_control(struct hvsi_struct *hp, uint8_t *packet,
struct tty_struct **to_hangup, struct hvsi_struct **to_handshake)
struct tty_struct *tty, struct hvsi_struct **to_handshake)
{
struct hvsi_control *header = (struct hvsi_control *)packet;

Expand All @@ -247,9 +247,8 @@ static void hvsi_recv_control(struct hvsi_struct *hp, uint8_t *packet,
/* CD went away; no more connection */
pr_debug("hvsi%i: CD dropped\n", hp->index);
hp->mctrl &= TIOCM_CD;
/* If userland hasn't done an open(2) yet, hp->tty is NULL. */
if (hp->tty && !C_CLOCAL(hp->tty))
*to_hangup = hp->tty;
if (tty && !C_CLOCAL(tty))
tty_hangup(tty);
}
break;
case VSV_CLOSE_PROTOCOL:
Expand Down Expand Up @@ -331,7 +330,8 @@ static void hvsi_recv_query(struct hvsi_struct *hp, uint8_t *packet)
}
}

static void hvsi_insert_chars(struct hvsi_struct *hp, const char *buf, int len)
static void hvsi_insert_chars(struct hvsi_struct *hp, struct tty_struct *tty,
const char *buf, int len)
{
int i;

Expand All @@ -347,7 +347,7 @@ static void hvsi_insert_chars(struct hvsi_struct *hp, const char *buf, int len)
continue;
}
#endif /* CONFIG_MAGIC_SYSRQ */
tty_insert_flip_char(hp->tty, c, 0);
tty_insert_flip_char(tty, c, 0);
}
}

Expand All @@ -360,7 +360,7 @@ static void hvsi_insert_chars(struct hvsi_struct *hp, const char *buf, int len)
* revisited.
*/
#define TTY_THRESHOLD_THROTTLE 128
static struct tty_struct *hvsi_recv_data(struct hvsi_struct *hp,
static bool hvsi_recv_data(struct hvsi_struct *hp, struct tty_struct *tty,
const uint8_t *packet)
{
const struct hvsi_header *header = (const struct hvsi_header *)packet;
Expand All @@ -371,14 +371,14 @@ static struct tty_struct *hvsi_recv_data(struct hvsi_struct *hp,
pr_debug("queueing %i chars '%.*s'\n", datalen, datalen, data);

if (datalen == 0)
return NULL;
return false;

if (overflow > 0) {
pr_debug("%s: got >TTY_THRESHOLD_THROTTLE bytes\n", __func__);
datalen = TTY_THRESHOLD_THROTTLE;
}

hvsi_insert_chars(hp, data, datalen);
hvsi_insert_chars(hp, tty, data, datalen);

if (overflow > 0) {
/*
Expand All @@ -390,7 +390,7 @@ static struct tty_struct *hvsi_recv_data(struct hvsi_struct *hp,
hp->n_throttle = overflow;
}

return hp->tty;
return true;
}

/*
Expand All @@ -399,14 +399,13 @@ static struct tty_struct *hvsi_recv_data(struct hvsi_struct *hp,
* machine during console handshaking (in which case tty = NULL and we ignore
* incoming data).
*/
static int hvsi_load_chunk(struct hvsi_struct *hp, struct tty_struct **flip,
struct tty_struct **hangup, struct hvsi_struct **handshake)
static int hvsi_load_chunk(struct hvsi_struct *hp, struct tty_struct *tty,
struct hvsi_struct **handshake)
{
uint8_t *packet = hp->inbuf;
int chunklen;
bool flip = false;

*flip = NULL;
*hangup = NULL;
*handshake = NULL;

chunklen = hvsi_read(hp, hp->inbuf_end, HVSI_MAX_READ);
Expand Down Expand Up @@ -440,12 +439,12 @@ static int hvsi_load_chunk(struct hvsi_struct *hp, struct tty_struct **flip,
case VS_DATA_PACKET_HEADER:
if (!is_open(hp))
break;
if (hp->tty == NULL)
if (tty == NULL)
break; /* no tty buffer to put data in */
*flip = hvsi_recv_data(hp, packet);
flip = hvsi_recv_data(hp, tty, packet);
break;
case VS_CONTROL_PACKET_HEADER:
hvsi_recv_control(hp, packet, hangup, handshake);
hvsi_recv_control(hp, packet, tty, handshake);
break;
case VS_QUERY_RESPONSE_PACKET_HEADER:
hvsi_recv_response(hp, packet);
Expand All @@ -462,28 +461,26 @@ static int hvsi_load_chunk(struct hvsi_struct *hp, struct tty_struct **flip,

packet += len_packet(packet);

if (*hangup || *handshake) {
pr_debug("%s: hangup or handshake\n", __func__);
/*
* we need to send the hangup now before receiving any more data.
* If we get "data, hangup, data", we can't deliver the second
* data before the hangup.
*/
if (*handshake) {
pr_debug("%s: handshake\n", __func__);
break;
}
}

compact_inbuf(hp, packet);

if (flip)
tty_flip_buffer_push(tty);

return 1;
}

static void hvsi_send_overflow(struct hvsi_struct *hp)
static void hvsi_send_overflow(struct hvsi_struct *hp, struct tty_struct *tty)
{
pr_debug("%s: delivering %i bytes overflow\n", __func__,
hp->n_throttle);

hvsi_insert_chars(hp, hp->throttle_buf, hp->n_throttle);
hvsi_insert_chars(hp, tty, hp->throttle_buf, hp->n_throttle);
hp->n_throttle = 0;
}

Expand All @@ -494,8 +491,6 @@ static void hvsi_send_overflow(struct hvsi_struct *hp)
static irqreturn_t hvsi_interrupt(int irq, void *arg)
{
struct hvsi_struct *hp = (struct hvsi_struct *)arg;
struct tty_struct *flip;
struct tty_struct *hangup;
struct hvsi_struct *handshake;
unsigned long flags;
int again = 1;
Expand All @@ -504,25 +499,9 @@ static irqreturn_t hvsi_interrupt(int irq, void *arg)

while (again) {
spin_lock_irqsave(&hp->lock, flags);
again = hvsi_load_chunk(hp, &flip, &hangup, &handshake);
again = hvsi_load_chunk(hp, hp->tty, &handshake);
spin_unlock_irqrestore(&hp->lock, flags);

/*
* we have to call tty_flip_buffer_push() and tty_hangup() outside our
* spinlock. But we also have to keep going until we've read all the
* available data.
*/

if (flip) {
/* there was data put in the tty flip buffer */
tty_flip_buffer_push(flip);
flip = NULL;
}

if (hangup) {
tty_hangup(hangup);
}

if (handshake) {
pr_debug("hvsi%i: attempting re-handshake\n", handshake->index);
schedule_work(&handshake->handshaker);
Expand All @@ -534,15 +513,11 @@ static irqreturn_t hvsi_interrupt(int irq, void *arg)
&& (!test_bit(TTY_THROTTLED, &hp->tty->flags))) {
/* we weren't hung up and we weren't throttled, so we can deliver the
* rest now */
flip = hp->tty;
hvsi_send_overflow(hp);
hvsi_send_overflow(hp, hp->tty);
tty_flip_buffer_push(hp->tty);
}
spin_unlock_irqrestore(&hp->lock, flags);

if (flip) {
tty_flip_buffer_push(flip);
}

return IRQ_HANDLED;
}

Expand Down Expand Up @@ -966,8 +941,8 @@ static int hvsi_write(struct tty_struct *tty,
* and hvsi_write_worker will be scheduled. subsequent hvsi_write() calls
* will see there is no room in outbuf and return.
*/
while ((count > 0) && (hvsi_write_room(hp->tty) > 0)) {
int chunksize = min(count, hvsi_write_room(hp->tty));
while ((count > 0) && (hvsi_write_room(tty) > 0)) {
int chunksize = min(count, hvsi_write_room(tty));

BUG_ON(hp->n_outbuf < 0);
memcpy(hp->outbuf + hp->n_outbuf, source, chunksize);
Expand Down Expand Up @@ -1014,19 +989,16 @@ static void hvsi_unthrottle(struct tty_struct *tty)
{
struct hvsi_struct *hp = tty->driver_data;
unsigned long flags;
int shouldflip = 0;

pr_debug("%s\n", __func__);

spin_lock_irqsave(&hp->lock, flags);
if (hp->n_throttle) {
hvsi_send_overflow(hp);
shouldflip = 1;
hvsi_send_overflow(hp, tty);
tty_flip_buffer_push(tty);
}
spin_unlock_irqrestore(&hp->lock, flags);

if (shouldflip)
tty_flip_buffer_push(hp->tty);

h_vio_signal(hp->vtermno, VIO_IRQ_ENABLE);
}
Expand Down

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