[Xen-devel,08/25,v6] xen/arm: vpl011: Modify xenconsole to define and use a new console structure

Message ID 1500296815-10243-9-git-send-email-bhupinder.thakur@linaro.org
State Superseded
Headers show
Series
  • SBSA UART emulation support in Xen
Related show

Commit Message

Bhupinder Thakur July 17, 2017, 1:06 p.m.
Xenconsole uses a domain structure which contains console specific fields. This
patch defines a new console structure, which would be used by the xenconsole
functions to perform console specific operations like reading/writing data from/to
the console ring buffer or reading/writing data from/to console tty.

This patch is in preparation to support multiple consoles to support vuart console.

Signed-off-by: Bhupinder Thakur <bhupinder.thakur@linaro.org>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Acked-by: Wei Liu <wei.liu2@citrix.com>
---
CC: Ian Jackson <ian.jackson@eu.citrix.com>
CC: Wei Liu <wei.liu2@citrix.com>
CC: Stefano Stabellini <sstabellini@kernel.org>
CC: Julien Grall <julien.grall@arm.com>

Changes since v4:
- Moved the following fields from the struct domain to struct console:
  ->xenevtchn_handle *xce_handle;
  ->int xce_pollfd_idx;
  ->int event_count;
  ->long long next_period;

Changes since v3:
- The changes in xenconsole have been split into four patches. This is the first patch
  which modifies the xenconsole to use a new console structure.

Changes since v2:
- Defined a new function console_create_ring() which sets up the ring buffer and 
  event channel a new console. domain_create_ring() uses this function to setup
  a console.
- This patch does not contain vuart specific changes, which would be introduced in
  the next patch.
- Changes for keeping the PV log file name unchanged.

Changes since v1:
- Split the domain struture to a separate console structure
- Modified the functions to operate on the console struture
- Replaced repetitive per console code with generic code

 tools/console/daemon/io.c | 299 +++++++++++++++++++++++++---------------------
 1 file changed, 165 insertions(+), 134 deletions(-)

Patch

diff --git a/tools/console/daemon/io.c b/tools/console/daemon/io.c
index e8033d2..30cd167 100644
--- a/tools/console/daemon/io.c
+++ b/tools/console/daemon/io.c
@@ -89,25 +89,30 @@  struct buffer {
 	size_t max_capacity;
 };
 
-struct domain {
-	int domid;
+struct console {
 	int master_fd;
 	int master_pollfd_idx;
 	int slave_fd;
 	int log_fd;
-	bool is_dead;
-	unsigned last_seen;
 	struct buffer buffer;
-	struct domain *next;
 	char *conspath;
 	int ring_ref;
-	xenevtchn_port_or_error_t local_port;
-	xenevtchn_port_or_error_t remote_port;
 	xenevtchn_handle *xce_handle;
 	int xce_pollfd_idx;
-	struct xencons_interface *interface;
 	int event_count;
 	long long next_period;
+	xenevtchn_port_or_error_t local_port;
+	xenevtchn_port_or_error_t remote_port;
+	struct xencons_interface *interface;
+	struct domain *d;
+};
+
+struct domain {
+	int domid;
+	bool is_dead;
+	unsigned last_seen;
+	struct domain *next;
+	struct console console;
 };
 
 static struct domain *dom_head;
@@ -160,9 +165,10 @@  static int write_with_timestamp(int fd, const char *data, size_t sz,
 
 static void buffer_append(struct domain *dom)
 {
-	struct buffer *buffer = &dom->buffer;
+	struct console *con = &dom->console;
+	struct buffer *buffer = &con->buffer;
 	XENCONS_RING_IDX cons, prod, size;
-	struct xencons_interface *intf = dom->interface;
+	struct xencons_interface *intf = con->interface;
 
 	cons = intf->out_cons;
 	prod = intf->out_prod;
@@ -187,22 +193,22 @@  static void buffer_append(struct domain *dom)
 
 	xen_mb();
 	intf->out_cons = cons;
-	xenevtchn_notify(dom->xce_handle, dom->local_port);
+	xenevtchn_notify(con->xce_handle, con->local_port);
 
 	/* Get the data to the logfile as early as possible because if
 	 * no one is listening on the console pty then it will fill up
 	 * and handle_tty_write will stop being called.
 	 */
-	if (dom->log_fd != -1) {
+	if (con->log_fd != -1) {
 		int logret;
 		if (log_time_guest) {
 			logret = write_with_timestamp(
-				dom->log_fd,
+				con->log_fd,
 				buffer->data + buffer->size - size,
 				size, &log_time_guest_needts);
 		} else {
 			logret = write_all(
-				dom->log_fd,
+				con->log_fd,
 				buffer->data + buffer->size - size,
 				size);
 		}
@@ -338,14 +344,16 @@  static int create_domain_log(struct domain *dom)
 
 static void domain_close_tty(struct domain *dom)
 {
-	if (dom->master_fd != -1) {
-		close(dom->master_fd);
-		dom->master_fd = -1;
+	struct console *con = &dom->console;
+
+	if (con->master_fd != -1) {
+		close(con->master_fd);
+		con->master_fd = -1;
 	}
 
-	if (dom->slave_fd != -1) {
-		close(dom->slave_fd);
-		dom->slave_fd = -1;
+	if (con->slave_fd != -1) {
+		close(con->slave_fd);
+		con->slave_fd = -1;
 	}
 }
 
@@ -418,11 +426,12 @@  static int domain_create_tty(struct domain *dom)
 	char *data;
 	unsigned int len;
 	struct termios term;
+	struct console *con = &dom->console;
 
-	assert(dom->slave_fd == -1);
-	assert(dom->master_fd == -1);
+	assert(con->slave_fd == -1);
+	assert(con->master_fd == -1);
 
-	if (openpty(&dom->master_fd, &dom->slave_fd, NULL, NULL, NULL) < 0) {
+	if (openpty(&con->master_fd, &con->slave_fd, NULL, NULL, NULL) < 0) {
 		err = errno;
 		dolog(LOG_ERR, "Failed to create tty for domain-%d "
 		      "(errno = %i, %s)",
@@ -430,7 +439,7 @@  static int domain_create_tty(struct domain *dom)
 		return 0;
 	}
 
-	if (tcgetattr(dom->slave_fd, &term) < 0) {
+	if (tcgetattr(con->slave_fd, &term) < 0) {
 		err = errno;
 		dolog(LOG_ERR, "Failed to get tty attributes for domain-%d "
 			"(errno = %i, %s)",
@@ -438,7 +447,7 @@  static int domain_create_tty(struct domain *dom)
 		goto out;
 	}
 	cfmakeraw(&term);
-	if (tcsetattr(dom->slave_fd, TCSANOW, &term) < 0) {
+	if (tcsetattr(con->slave_fd, TCSANOW, &term) < 0) {
 		err = errno;
 		dolog(LOG_ERR, "Failed to set tty attributes for domain-%d "
 			"(errno = %i, %s)",
@@ -446,7 +455,7 @@  static int domain_create_tty(struct domain *dom)
 		goto out;
 	}
 
-	if ((slave = ptsname(dom->master_fd)) == NULL) {
+	if ((slave = ptsname(con->master_fd)) == NULL) {
 		err = errno;
 		dolog(LOG_ERR, "Failed to get slave name for domain-%d "
 		      "(errno = %i, %s)",
@@ -454,18 +463,18 @@  static int domain_create_tty(struct domain *dom)
 		goto out;
 	}
 
-	success = asprintf(&path, "%s/limit", dom->conspath) !=
+	success = asprintf(&path, "%s/limit", con->conspath) !=
 		-1;
 	if (!success)
 		goto out;
 	data = xs_read(xs, XBT_NULL, path, &len);
 	if (data) {
-		dom->buffer.max_capacity = strtoul(data, 0, 0);
+		con->buffer.max_capacity = strtoul(data, 0, 0);
 		free(data);
 	}
 	free(path);
 
-	success = (asprintf(&path, "%s/tty", dom->conspath) != -1);
+	success = (asprintf(&path, "%s/tty", con->conspath) != -1);
 	if (!success)
 		goto out;
 	success = xs_write(xs, XBT_NULL, path, slave, strlen(slave));
@@ -473,7 +482,7 @@  static int domain_create_tty(struct domain *dom)
 	if (!success)
 		goto out;
 
-	if (fcntl(dom->master_fd, F_SETFL, O_NONBLOCK) == -1)
+	if (fcntl(con->master_fd, F_SETFL, O_NONBLOCK) == -1)
 		goto out;
 
 	return 1;
@@ -519,29 +528,32 @@  static int xs_gather(struct xs_handle *xs, const char *dir, ...)
 
 static void domain_unmap_interface(struct domain *dom)
 {
-	if (dom->interface == NULL)
+	struct console *con = &dom->console;
+
+	if (con->interface == NULL)
 		return;
-	if (xgt_handle && dom->ring_ref == -1)
-		xengnttab_unmap(xgt_handle, dom->interface, 1);
+	if (xgt_handle && con->ring_ref == -1)
+		xengnttab_unmap(xgt_handle, con->interface, 1);
 	else
-		munmap(dom->interface, XC_PAGE_SIZE);
-	dom->interface = NULL;
-	dom->ring_ref = -1;
+		munmap(con->interface, XC_PAGE_SIZE);
+	con->interface = NULL;
+	con->ring_ref = -1;
 }
  
 static int domain_create_ring(struct domain *dom)
 {
 	int err, remote_port, ring_ref, rc;
 	char *type, path[PATH_MAX];
+	struct console *con = &dom->console;
 
-	err = xs_gather(xs, dom->conspath,
+	err = xs_gather(xs, con->conspath,
 			"ring-ref", "%u", &ring_ref,
 			"port", "%i", &remote_port,
 			NULL);
 	if (err)
 		goto out;
 
-	snprintf(path, sizeof(path), "%s/type", dom->conspath);
+	snprintf(path, sizeof(path), "%s/type", con->conspath);
 	type = xs_read(xs, XBT_NULL, path, NULL);
 	if (type && strcmp(type, "xenconsoled") != 0) {
 		free(type);
@@ -550,77 +562,77 @@  static int domain_create_ring(struct domain *dom)
 	free(type);
 
 	/* If using ring_ref and it has changed, remap */
-	if (ring_ref != dom->ring_ref && dom->ring_ref != -1)
+	if (ring_ref != con->ring_ref && con->ring_ref != -1)
 		domain_unmap_interface(dom);
 
-	if (!dom->interface && xgt_handle) {
+	if (!con->interface && xgt_handle) {
 		/* Prefer using grant table */
-		dom->interface = xengnttab_map_grant_ref(xgt_handle,
+		con->interface = xengnttab_map_grant_ref(xgt_handle,
 			dom->domid, GNTTAB_RESERVED_CONSOLE,
 			PROT_READ|PROT_WRITE);
-		dom->ring_ref = -1;
+		con->ring_ref = -1;
 	}
-	if (!dom->interface) {
+	if (!con->interface) {
 		/* Fall back to xc_map_foreign_range */
-		dom->interface = xc_map_foreign_range(
+		con->interface = xc_map_foreign_range(
 			xc, dom->domid, XC_PAGE_SIZE,
 			PROT_READ|PROT_WRITE,
 			(unsigned long)ring_ref);
-		if (dom->interface == NULL) {
+		if (con->interface == NULL) {
 			err = EINVAL;
 			goto out;
 		}
-		dom->ring_ref = ring_ref;
+		con->ring_ref = ring_ref;
 	}
 
 	/* Go no further if port has not changed and we are still bound. */
-	if (remote_port == dom->remote_port) {
+	if (remote_port == con->remote_port) {
 		xc_evtchn_status_t status = {
 			.dom = DOMID_SELF,
-			.port = dom->local_port };
+			.port = con->local_port };
 		if ((xc_evtchn_status(xc, &status) == 0) &&
 		    (status.status == EVTCHNSTAT_interdomain))
 			goto out;
 	}
 
-	dom->local_port = -1;
-	dom->remote_port = -1;
-	if (dom->xce_handle != NULL)
-		xenevtchn_close(dom->xce_handle);
+	con->local_port = -1;
+	con->remote_port = -1;
+	if (con->xce_handle != NULL)
+		xenevtchn_close(con->xce_handle);
 
 	/* Opening evtchn independently for each console is a bit
 	 * wasteful, but that's how the code is structured... */
-	dom->xce_handle = xenevtchn_open(NULL, 0);
-	if (dom->xce_handle == NULL) {
+	con->xce_handle = xenevtchn_open(NULL, 0);
+	if (con->xce_handle == NULL) {
 		err = errno;
 		goto out;
 	}
  
-	rc = xenevtchn_bind_interdomain(dom->xce_handle,
+	rc = xenevtchn_bind_interdomain(con->xce_handle,
 		dom->domid, remote_port);
 
 	if (rc == -1) {
 		err = errno;
-		xenevtchn_close(dom->xce_handle);
-		dom->xce_handle = NULL;
+		xenevtchn_close(con->xce_handle);
+		con->xce_handle = NULL;
 		goto out;
 	}
-	dom->local_port = rc;
-	dom->remote_port = remote_port;
+	con->local_port = rc;
+	con->remote_port = remote_port;
 
-	if (dom->master_fd == -1) {
+	if (con->master_fd == -1) {
 		if (!domain_create_tty(dom)) {
 			err = errno;
-			xenevtchn_close(dom->xce_handle);
-			dom->xce_handle = NULL;
-			dom->local_port = -1;
-			dom->remote_port = -1;
+			xenevtchn_close(con->xce_handle);
+			con->xce_handle = NULL;
+			con->local_port = -1;
+			con->remote_port = -1;
 			goto out;
 		}
 	}
 
-	if (log_guest && (dom->log_fd == -1))
-		dom->log_fd = create_domain_log(dom);
+	if (log_guest && (con->log_fd == -1))
+		con->log_fd = create_domain_log(dom);
 
  out:
 	return err;
@@ -630,16 +642,17 @@  static bool watch_domain(struct domain *dom, bool watch)
 {
 	char domid_str[3 + MAX_STRLEN(dom->domid)];
 	bool success;
+	struct console *con = &dom->console;
 
 	snprintf(domid_str, sizeof(domid_str), "dom%u", dom->domid);
 	if (watch) {
-		success = xs_watch(xs, dom->conspath, domid_str);
+		success = xs_watch(xs, con->conspath, domid_str);
 		if (success)
 			domain_create_ring(dom);
 		else
-			xs_unwatch(xs, dom->conspath, domid_str);
+			xs_unwatch(xs, con->conspath, domid_str);
 	} else {
-		success = xs_unwatch(xs, dom->conspath, domid_str);
+		success = xs_unwatch(xs, con->conspath, domid_str);
 	}
 
 	return success;
@@ -651,6 +664,7 @@  static struct domain *create_domain(int domid)
 	struct domain *dom;
 	char *s;
 	struct timespec ts;
+	struct console *con;
 
 	if (clock_gettime(CLOCK_MONOTONIC, &ts) < 0) {
 		dolog(LOG_ERR, "Cannot get time of day %s:%s:L%d",
@@ -667,25 +681,26 @@  static struct domain *create_domain(int domid)
 
 	dom->domid = domid;
 
-	dom->conspath = xs_get_domain_path(xs, dom->domid);
-	s = realloc(dom->conspath, strlen(dom->conspath) +
+	con = &dom->console;
+	con->conspath = xs_get_domain_path(xs, dom->domid);
+	s = realloc(con->conspath, strlen(con->conspath) +
 		    strlen("/console") + 1);
 	if (s == NULL)
 		goto out;
-	dom->conspath = s;
-	strcat(dom->conspath, "/console");
+	con->conspath = s;
+	strcat(con->conspath, "/console");
 
-	dom->master_fd = -1;
-	dom->master_pollfd_idx = -1;
-	dom->slave_fd = -1;
-	dom->log_fd = -1;
-	dom->xce_pollfd_idx = -1;
+	con->master_fd = -1;
+	con->master_pollfd_idx = -1;
+	con->slave_fd = -1;
+	con->log_fd = -1;
+	con->xce_pollfd_idx = -1;
 
-	dom->next_period = ((long long)ts.tv_sec * 1000) + (ts.tv_nsec / 1000000) + RATE_LIMIT_PERIOD;
+	con->next_period = ((long long)ts.tv_sec * 1000) + (ts.tv_nsec / 1000000) + RATE_LIMIT_PERIOD;
 
-	dom->ring_ref = -1;
-	dom->local_port = -1;
-	dom->remote_port = -1;
+	con->ring_ref = -1;
+	con->local_port = -1;
+	con->remote_port = -1;
 
 	if (!watch_domain(dom, true))
 		goto out;
@@ -697,7 +712,7 @@  static struct domain *create_domain(int domid)
 
 	return dom;
  out:
-	free(dom->conspath);
+	free(con->conspath);
 	free(dom);
 	return NULL;
 }
@@ -729,30 +744,34 @@  static void remove_domain(struct domain *dom)
 
 static void cleanup_domain(struct domain *d)
 {
+	struct console *con = &d->console;
+
 	domain_close_tty(d);
 
-	if (d->log_fd != -1) {
-		close(d->log_fd);
-		d->log_fd = -1;
+	if (con->log_fd != -1) {
+		close(con->log_fd);
+		con->log_fd = -1;
 	}
 
-	free(d->buffer.data);
-	d->buffer.data = NULL;
+	free(con->buffer.data);
+	con->buffer.data = NULL;
 
-	free(d->conspath);
-	d->conspath = NULL;
+	free(con->conspath);
+	con->conspath = NULL;
 
 	remove_domain(d);
 }
 
 static void shutdown_domain(struct domain *d)
 {
+	struct console *con = &d->console;
+
 	d->is_dead = true;
 	watch_domain(d, false);
 	domain_unmap_interface(d);
-	if (d->xce_handle != NULL)
-		xenevtchn_close(d->xce_handle);
-	d->xce_handle = NULL;
+	if (con->xce_handle != NULL)
+		xenevtchn_close(con->xce_handle);
+	con->xce_handle = NULL;
 }
 
 static unsigned enum_pass = 0;
@@ -782,7 +801,8 @@  static void enum_domains(void)
 
 static int ring_free_bytes(struct domain *dom)
 {
-	struct xencons_interface *intf = dom->interface;
+	struct console *con = &dom->console;
+	struct xencons_interface *intf = con->interface;
 	XENCONS_RING_IDX cons, prod, space;
 
 	cons = intf->in_cons;
@@ -812,7 +832,8 @@  static void handle_tty_read(struct domain *dom)
 	ssize_t len = 0;
 	char msg[80];
 	int i;
-	struct xencons_interface *intf = dom->interface;
+	struct console *con = &dom->console;
+	struct xencons_interface *intf = con->interface;
 	XENCONS_RING_IDX prod;
 
 	if (dom->is_dead)
@@ -825,7 +846,7 @@  static void handle_tty_read(struct domain *dom)
 	if (len > sizeof(msg))
 		len = sizeof(msg);
 
-	len = read(dom->master_fd, msg, len);
+	len = read(con->master_fd, msg, len);
 	/*
 	 * Note: on Solaris, len == 0 means the slave closed, and this
 	 * is no problem, but Linux can't handle this usefully, so we
@@ -841,7 +862,7 @@  static void handle_tty_read(struct domain *dom)
 		}
 		xen_wmb();
 		intf->in_prod = prod;
-		xenevtchn_notify(dom->xce_handle, dom->local_port);
+		xenevtchn_notify(con->xce_handle, con->local_port);
 	} else {
 		domain_close_tty(dom);
 		shutdown_domain(dom);
@@ -851,37 +872,39 @@  static void handle_tty_read(struct domain *dom)
 static void handle_tty_write(struct domain *dom)
 {
 	ssize_t len;
+	struct console *con = &dom->console;
 
 	if (dom->is_dead)
 		return;
 
-	len = write(dom->master_fd, dom->buffer.data + dom->buffer.consumed,
-		    dom->buffer.size - dom->buffer.consumed);
+	len = write(con->master_fd, con->buffer.data + con->buffer.consumed,
+		    con->buffer.size - con->buffer.consumed);
  	if (len < 1) {
 		dolog(LOG_DEBUG, "Write failed on domain %d: %zd, %d\n",
 		      dom->domid, len, errno);
 		domain_handle_broken_tty(dom, domain_is_valid(dom->domid));
 	} else {
-		buffer_advance(&dom->buffer, len);
+		buffer_advance(&con->buffer, len);
 	}
 }
 
 static void handle_ring_read(struct domain *dom)
 {
 	xenevtchn_port_or_error_t port;
+	struct console *con = &dom->console;
 
 	if (dom->is_dead)
 		return;
 
-	if ((port = xenevtchn_pending(dom->xce_handle)) == -1)
+	if ((port = xenevtchn_pending(con->xce_handle)) == -1)
 		return;
 
-	dom->event_count++;
+	con->event_count++;
 
 	buffer_append(dom);
 
-	if (dom->event_count < RATE_LIMIT_ALLOWANCE)
-		(void)xenevtchn_unmask(dom->xce_handle, port);
+	if (con->event_count < RATE_LIMIT_ALLOWANCE)
+		(void)xenevtchn_unmask(con->xce_handle, port);
 }
 
 static void handle_xs(void)
@@ -948,9 +971,11 @@  static void handle_log_reload(void)
 	if (log_guest) {
 		struct domain *d;
 		for (d = dom_head; d; d = d->next) {
-			if (d->log_fd != -1)
-				close(d->log_fd);
-			d->log_fd = create_domain_log(d);
+			struct console *con = &d->console;
+
+			if (con->log_fd != -1)
+				close(con->log_fd);
+			con->log_fd = create_domain_log(d);
 		}
 	}
 
@@ -1059,48 +1084,52 @@  void handle_io(void)
 		/* Re-calculate any event counter allowances & unblock
 		   domains with new allowance */
 		for (d = dom_head; d; d = d->next) {
+			struct console *con = &d->console;
+
 			/* CS 16257:955ee4fa1345 introduces a 5ms fuzz
 			 * for select(), it is not clear poll() has
 			 * similar behavior (returning a couple of ms
 			 * sooner than requested) as well. Just leave
 			 * the fuzz here. Remove it with a separate
 			 * patch if necessary */
-			if ((now+5) > d->next_period) {
-				d->next_period = now + RATE_LIMIT_PERIOD;
-				if (d->event_count >= RATE_LIMIT_ALLOWANCE) {
-					(void)xenevtchn_unmask(d->xce_handle, d->local_port);
+			if ((now+5) > con->next_period) {
+				con->next_period = now + RATE_LIMIT_PERIOD;
+				if (con->event_count >= RATE_LIMIT_ALLOWANCE) {
+					(void)xenevtchn_unmask(con->xce_handle, con->local_port);
 				}
-				d->event_count = 0;
+				con->event_count = 0;
 			}
 		}
 
 		for (d = dom_head; d; d = d->next) {
-			if (d->event_count >= RATE_LIMIT_ALLOWANCE) {
+			struct console *con = &d->console;
+
+			if (con->event_count >= RATE_LIMIT_ALLOWANCE) {
 				/* Determine if we're going to be the next time slice to expire */
 				if (!next_timeout ||
-				    d->next_period < next_timeout)
-					next_timeout = d->next_period;
-			} else if (d->xce_handle != NULL) {
+				    con->next_period < next_timeout)
+					next_timeout = con->next_period;
+			} else if (con->xce_handle != NULL) {
 				if (discard_overflowed_data ||
-				    !d->buffer.max_capacity ||
-				    d->buffer.size < d->buffer.max_capacity) {
-					int evtchn_fd = xenevtchn_fd(d->xce_handle);
-					d->xce_pollfd_idx = set_fds(evtchn_fd,
+				    !con->buffer.max_capacity ||
+				    con->buffer.size < con->buffer.max_capacity) {
+					int evtchn_fd = xenevtchn_fd(con->xce_handle);
+					con->xce_pollfd_idx = set_fds(evtchn_fd,
 								    POLLIN|POLLPRI);
 				}
 			}
 
-			if (d->master_fd != -1) {
+			if (con->master_fd != -1) {
 				short events = 0;
 				if (!d->is_dead && ring_free_bytes(d))
 					events |= POLLIN;
 
-				if (!buffer_empty(&d->buffer))
+				if (!buffer_empty(&con->buffer))
 					events |= POLLOUT;
 
 				if (events)
-					d->master_pollfd_idx =
-						set_fds(d->master_fd,
+					con->master_pollfd_idx =
+						set_fds(con->master_fd,
 							events|POLLPRI);
 			}
 		}
@@ -1163,33 +1192,35 @@  void handle_io(void)
 		}
 
 		for (d = dom_head; d; d = n) {
+			struct console *con = &d->console;
+
 			n = d->next;
-			if (d->event_count < RATE_LIMIT_ALLOWANCE) {
-				if (d->xce_handle != NULL &&
-				    d->xce_pollfd_idx != -1 &&
-				    !(fds[d->xce_pollfd_idx].revents &
+			if (con->event_count < RATE_LIMIT_ALLOWANCE) {
+				if (con->xce_handle != NULL &&
+				    con->xce_pollfd_idx != -1 &&
+				    !(fds[con->xce_pollfd_idx].revents &
 				      ~(POLLIN|POLLOUT|POLLPRI)) &&
-				      (fds[d->xce_pollfd_idx].revents &
+				      (fds[con->xce_pollfd_idx].revents &
 				       POLLIN))
 				    handle_ring_read(d);
 			}
 
-			if (d->master_fd != -1 && d->master_pollfd_idx != -1) {
-				if (fds[d->master_pollfd_idx].revents &
+			if (con->master_fd != -1 && con->master_pollfd_idx != -1) {
+				if (fds[con->master_pollfd_idx].revents &
 				    ~(POLLIN|POLLOUT|POLLPRI))
 					domain_handle_broken_tty(d,
 						   domain_is_valid(d->domid));
 				else {
-					if (fds[d->master_pollfd_idx].revents &
+					if (fds[con->master_pollfd_idx].revents &
 					    POLLIN)
 						handle_tty_read(d);
-					if (fds[d->master_pollfd_idx].revents &
+					if (fds[con->master_pollfd_idx].revents &
 					    POLLOUT)
 						handle_tty_write(d);
 				}
 			}
 
-			d->xce_pollfd_idx = d->master_pollfd_idx = -1;
+			con->xce_pollfd_idx = con->master_pollfd_idx = -1;
 
 			if (d->last_seen != enum_pass)
 				shutdown_domain(d);