From: Stefano Stabellini Subject: [PATCH] replacing gettimeofday with clock_gettime in xenconsoled Date: Tue, 29 Jul 2008 16:31:20 +0100 Message-ID: <488F37C8.6020006@eu.citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org Hi all, currently if someone changes the date on the host, xenconsoled may behave incorrectly due to the use of gettimeofday for the rate control algorithm. For example I was able to hang the console connected to a guest just setting the date forward 20 years. To solve the problem we need to use a time source that doesn't change start point, that is clock_gettime with CLOCK_MONOTONIC. The only bad side effect is that it introduces a dependency to librt, but I think is well worth it. Signed-off-by: Stefano Stabellini --- diff -r a538185695ed tools/console/Makefile --- a/tools/console/Makefile Tue Jul 29 15:10:58 2008 +0100 +++ b/tools/console/Makefile Tue Jul 29 15:47:29 2008 +0100 @@ -21,7 +21,7 @@ clean: xenconsoled: $(patsubst %.c,%.o,$(wildcard daemon/*.c)) $(CC) $(CFLAGS) $^ -o $@ $(LDFLAGS) \ - $(UTIL_LIBS) $(SOCKET_LIBS) + $(UTIL_LIBS) $(SOCKET_LIBS) -lrt xenconsole: $(patsubst %.c,%.o,$(wildcard client/*.c)) $(CC) $(CFLAGS) $^ -o $@ $(LDFLAGS) \ diff -r a538185695ed tools/console/daemon/io.c --- a/tools/console/daemon/io.c Tue Jul 29 15:10:58 2008 +0100 +++ b/tools/console/daemon/io.c Tue Jul 29 15:44:59 2008 +0100 @@ -622,9 +622,9 @@ static struct domain *create_domain(int { struct domain *dom; char *s; - struct timeval tv; - - if (gettimeofday(&tv, NULL) < 0) { + struct timespec ts; + + if (clock_gettime(CLOCK_MONOTONIC, &ts) < 0) { dolog(LOG_ERR, "Cannot get time of day %s:%s:L%d", __FILE__, __FUNCTION__, __LINE__); return NULL; @@ -666,7 +666,7 @@ static struct domain *create_domain(int dom->buffer.capacity = 0; dom->buffer.max_capacity = 0; dom->event_count = 0; - dom->next_period = (tv.tv_sec * 1000) + (tv.tv_usec / 1000) + RATE_LIMIT_PERIOD; + dom->next_period = (ts.tv_sec * 1000) + (ts.tv_nsec / 1000000) + RATE_LIMIT_PERIOD; dom->next = NULL; dom->ring_ref = -1; @@ -971,7 +971,7 @@ void handle_io(void) struct domain *d, *n; int max_fd = -1; struct timeval timeout; - struct timeval tv; + struct timespec ts; long long now, next_timeout = 0; FD_ZERO(&readfds); @@ -985,9 +985,9 @@ void handle_io(void) max_fd = MAX(xc_evtchn_fd(xce_handle), max_fd); } - if (gettimeofday(&tv, NULL) < 0) + if (clock_gettime(CLOCK_MONOTONIC, &ts) < 0) return; - now = (tv.tv_sec * 1000) + (tv.tv_usec / 1000); + now = (ts.tv_sec * 1000) + (ts.tv_nsec / 1000000); /* Re-calculate any event counter allowances & unblock domains with new allowance */