From 32fea6eb04cecfcce4859233394d57dc6042ba34 Mon Sep 17 00:00:00 2001 From: Shaun Ruffell Date: Tue, 4 Aug 2009 16:22:39 +0000 Subject: dahdi_dummy: Do not allow jumps in system time to lock up the system. Since dahdi_dummy uses the number of milliseconds that has actually passed to determine how many times to call dahdi_receive, it is possible that if the system time shifts after dahdi is started, that the system can appear to lock up while dahdi_dummy attempts to catch up. This change prevents soft lock ups under these conditions. (closes issue #15647) Reported by: missnebun git-svn-id: http://svn.asterisk.org/svn/dahdi/linux/trunk@6933 a0bf4364-ded3-4de4-8d8a-66a801d63aff --- drivers/dahdi/dahdi_dummy.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/drivers/dahdi/dahdi_dummy.c b/drivers/dahdi/dahdi_dummy.c index d0297c3..da6fa44 100644 --- a/drivers/dahdi/dahdi_dummy.c +++ b/drivers/dahdi/dahdi_dummy.c @@ -161,12 +161,31 @@ static void dahdi_dummy_timer(unsigned long param) unsigned long ms_since_start; struct timespec now; const unsigned long MAX_INTERVAL = 100000L; + const unsigned long MS_LIMIT = 3000; if (!atomic_read(&shutdown)) mod_timer(&timer, jiffies + JIFFIES_INTERVAL); now = current_kernel_time(); ms_since_start = timespec_diff_ms(&ztd->start_interval, &now); + + /* + * If the system time has changed, it is possible for us to be far + * behind. If we are more than MS_LIMIT milliseconds behind, just + * reset our time base and continue so that we do not hang the system + * here. + * + */ + if (unlikely((ms_since_start - ztd->calls_since_start) > MS_LIMIT)) { + if (printk_ratelimit()) { + printk(KERN_INFO + "dahdi_dummy: Detected time shift.\n"); + } + ztd->calls_since_start = 0; + ztd->start_interval = now; + return; + } + while (ms_since_start > ztd->calls_since_start) { ztd->calls_since_start++; dahdi_receive(&ztd->span); -- cgit v1.2.3