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Groups > linux.kernel > #1403815
| From | Ming Lei <ming.lei@canonical.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH] fbcon: use default if cursor blink interval is not valid |
| Date | 2016-05-19 17:40 +0200 |
| Message-ID | <rAydk-1Ak-17@gated-at.bofh.it> (permalink) |
| References | (3 earlier) <rAgq6-6Tl-7@gated-at.bofh.it> <rAnKV-3m2-7@gated-at.bofh.it> <rAnKV-3m2-5@gated-at.bofh.it> <rAs7U-6aN-25@gated-at.bofh.it> <rAx7E-Wa-5@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Thu, May 19, 2016 at 10:22 PM, Scot Doyle <lkml14@scotdoyle.com> wrote:
> 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@ucw.cz>
>>
>> > 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:
If 'jiffies' is passed to mod_timer() for same timer unusually OR
mod_timer() isn't called from the timer handler, it shoudln't cause
soft lockup.
In the case of fbcon, 'jiffies' is always passed to mod_timer() and
mod_timer() is called from the timer handler meantime, that is a
real lockup.
>
> 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?
>
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[PATCH] tty: vt: Fix soft lockup in fbcon cursor blink timer. David Daney <ddaney.cavm@gmail.com> - 2016-05-17 20:50 +0200
Re: [PATCH] tty: vt: Fix soft lockup in fbcon cursor blink timer. Pavel Machek <pavel@ucw.cz> - 2016-05-17 22:50 +0200
Re: [PATCH] tty: vt: Fix soft lockup in fbcon cursor blink timer. Ming Lei <ming.lei@canonical.com> - 2016-05-18 02:50 +0200
Re: [PATCH] tty: vt: Fix soft lockup in fbcon cursor blink timer. Scot Doyle <lkml14@scotdoyle.com> - 2016-05-18 22:40 +0200
Re: [PATCH] tty: vt: Fix soft lockup in fbcon cursor blink timer. Ming Lei <ming.lei@canonical.com> - 2016-05-19 02:30 +0200
Re: [PATCH] tty: vt: Fix soft lockup in fbcon cursor blink timer. Pavel Machek <pavel@ucw.cz> - 2016-05-19 09:10 +0200
[PATCH] fbcon: use default if cursor blink interval is not valid Scot Doyle <lkml14@scotdoyle.com> - 2016-05-19 06:30 +0200
Re: [PATCH] fbcon: use default if cursor blink interval is not valid Jeremy Kerr <jk@ozlabs.org> - 2016-05-19 09:30 +0200
Re: [PATCH] fbcon: use default if cursor blink interval is not valid Ming Lei <ming.lei@canonical.com> - 2016-05-19 10:40 +0200
Re: [PATCH] fbcon: use default if cursor blink interval is not valid Pavel Machek <pavel@ucw.cz> - 2016-05-19 11:10 +0200
Re: [PATCH] fbcon: use default if cursor blink interval is not valid Scot Doyle <lkml14@scotdoyle.com> - 2016-05-19 16:30 +0200
Re: [PATCH] fbcon: use default if cursor blink interval is not valid Ming Lei <ming.lei@canonical.com> - 2016-05-19 17:40 +0200
Re: [PATCH] fbcon: use default if cursor blink interval is not valid Scot Doyle <lkml14@scotdoyle.com> - 2016-05-20 00:30 +0200
[PATCH] fbcon: warn on invalid cursor blink intervals Scot Doyle <lkml14@scotdoyle.com> - 2016-05-20 00:40 +0200
Re: [PATCH] fbcon: warn on invalid cursor blink intervals Jeremy Kerr <jk@ozlabs.org> - 2016-05-20 03:30 +0200
Re: [PATCH] fbcon: warn on invalid cursor blink intervals Ming Lei <ming.lei@canonical.com> - 2016-05-20 04:20 +0200
Re: [PATCH] fbcon: warn on invalid cursor blink intervals Jeremy Kerr <jk@ozlabs.org> - 2016-05-20 04:30 +0200
Re: [PATCH] fbcon: warn on invalid cursor blink intervals Ming Lei <ming.lei@canonical.com> - 2016-05-20 04:50 +0200
Re: [PATCH] fbcon: warn on invalid cursor blink intervals Jeremy Kerr <jk@ozlabs.org> - 2016-05-20 07:10 +0200
Re: [PATCH] fbcon: warn on invalid cursor blink intervals Scot Doyle <lkml14@scotdoyle.com> - 2016-05-20 18:30 +0200
Re: [PATCH] fbcon: warn on invalid cursor blink intervals Scot Doyle <lkml14@scotdoyle.com> - 2016-05-24 03:30 +0200
Re: [PATCH] fbcon: warn on invalid cursor blink intervals Henrique de Moraes Holschuh <hmh@hmh.eng.br> - 2016-05-28 13:50 +0200
Re: [PATCH] fbcon: warn on invalid cursor blink intervals Henrique de Moraes Holschuh <hmh@hmh.eng.br> - 2016-05-28 13:50 +0200
Re: [PATCH] tty: vt: Fix soft lockup in fbcon cursor blink timer. Scot Doyle <lkml14@scotdoyle.com> - 2016-05-20 00:40 +0200
Re: [PATCH] tty: vt: Fix soft lockup in fbcon cursor blink timer. Henrique de Moraes Holschuh <hmh@hmh.eng.br> - 2016-05-28 13:50 +0200
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