On Thu, 19 May 2016, Pavel Machek wrote: > Hi! > > > Two current [1] and three previous [2] systems locked during boot > > because the cursor flash timer was set using an ops->cur_blink_jiffies > > value of 0. Previous patches attempted to solve the problem by moving > > variable initialization earlier in the setup sequence [2]. > > > > Use the normal cursor blink default interval of 200 ms if > > ops->cur_blink_jiffies is not in the range specified in commit > > bd63364caa8d. Since invalid values are not used, specific system > > initialization timings should not cause lockups. > > > > [1] https://bugs.launchpad.net/bugs/1574814 > > [2] see commits: 2a17d7e80f1d, f235f664a8af, a1e533ec07d5 > > Acked-by: Pavel Machek <pavel@xxxxxx> > > > static void cursor_timer_handler(unsigned long dev_addr) > > { > > struct fb_info *info = (struct fb_info *) dev_addr; > > struct fbcon_ops *ops = info->fbcon_par; > > > > queue_work(system_power_efficient_wq, &info->queue); > > - mod_timer(&ops->cursor_timer, jiffies + ops->cur_blink_jiffies); > > + mod_timer(&ops->cursor_timer, jiffies + > > + cursor_blink_jiffies(ops->cur_blink_jiffies)); > > } > > > > static void fbcon_add_cursor_timer(struct fb_info *info) > > And actually... perhaps mod_timer should have some check for too low > timeouts..? > > WARN_ON? > Pavel Interesting idea. I applied this patch to a couple systems and receive the same warning on both: diff --git a/kernel/time/timer.c b/kernel/time/timer.c index 73164c3..f6c0b69 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -788,6 +788,7 @@ __mod_timer(struct timer_list *timer, unsigned long expires, timer_stats_timer_set_start_info(timer); BUG_ON(!timer->function); + WARN_ONCE(expires == jiffies, "timer should expire in the future"); base = lock_timer_base(timer, &flags); ------ [ 2.060474] ------------[ cut here ]------------ [ 2.061613] WARNING: CPU: 0 PID: 164 at kernel/time/timer.c:791 mod_timer+0x233/0x240 [ 2.062740] timer should expire in the future [ 2.062757] CPU: 0 PID: 164 Comm: kworker/0:2 Not tainted 4.6.0+ #7 [ 2.065870] Hardware name: Toshiba Leon, BIOS 12/04/2013 [ 2.067828] Workqueue: events_power_efficient hub_init_func3 [ 2.069762] 0000000000000000 ffff88007443bbb8 ffffffff8139932b ffff88007443bc08 [ 2.071701] 0000000000000000 ffff88007443bbf8 ffffffff8112e57c 0000031700000000 [ 2.073655] ffff88007486a0b0 00000000fffea2da ffff88007486a000 0000000000000202 [ 2.075594] Call Trace: [ 2.077503] [<ffffffff8139932b>] dump_stack+0x4d/0x72 [ 2.079426] [<ffffffff8112e57c>] __warn+0xcc/0xf0 [ 2.081325] [<ffffffff8112e5ef>] warn_slowpath_fmt+0x4f/0x60 [ 2.083212] [<ffffffff813ad5e5>] ? find_next_bit+0x15/0x20 [ 2.085022] [<ffffffff8139914f>] ? cpumask_next_and+0x2f/0x40 [ 2.086696] [<ffffffff81188a93>] mod_timer+0x233/0x240 [ 2.088362] [<ffffffff815fff02>] usb_hcd_submit_urb+0x3f2/0x8c0 [ 2.090026] [<ffffffff81601dc4>] ? urb_destroy+0x24/0x30 [ 2.091698] [<ffffffff81142ba8>] ? insert_work+0x58/0xb0 [ 2.093349] [<ffffffff81602297>] usb_submit_urb+0x287/0x530 [ 2.094985] [<ffffffff815f986d>] hub_activate+0x1fd/0x5d0 [ 2.096625] [<ffffffff81150188>] ? finish_task_switch+0x78/0x1f0 [ 2.098268] [<ffffffff815f9cca>] hub_init_func3+0x1a/0x20 [ 2.099908] [<ffffffff811438e0>] process_one_work+0x140/0x3e0 [ 2.101539] [<ffffffff81143bce>] worker_thread+0x4e/0x480 [ 2.103173] [<ffffffff81143b80>] ? process_one_work+0x3e0/0x3e0 [ 2.104790] [<ffffffff81143b80>] ? process_one_work+0x3e0/0x3e0 [ 2.106259] [<ffffffff81149829>] kthread+0xc9/0xe0 [ 2.107731] [<ffffffff81856152>] ret_from_fork+0x22/0x40 [ 2.109215] [<ffffffff81149760>] ? __kthread_parkme+0x70/0x70 [ 2.110704] ---[ end trace 3519886a1a990d99 ]--- mod_timer is called from over a thousand places. Should timers always expire in the future? _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
