tty: vt: Fix soft lockup in fbcon cursor blink timer.

We are getting somewhat random soft lockups with this signature:

[   86.992215] [<fffffc00080935e0>] el1_irq+0xa0/0x10c
[   86.997082] [<fffffc000841822c>] cursor_timer_handler+0x30/0x54
[   87.002991] [<fffffc000810ec44>] call_timer_fn+0x54/0x1a8
[   87.008378] [<fffffc000810ef88>] run_timer_softirq+0x1c4/0x2bc
[   87.014200] [<fffffc000809077c>] __do_softirq+0x114/0x344
[   87.019590] [<fffffc00080af45c>] irq_exit+0x74/0x98
[   87.024458] [<fffffc00080fac20>] __handle_domain_irq+0x98/0xfc
[   87.030278] [<fffffc000809056c>] gic_handle_irq+0x94/0x190

This is caused by the vt visual_init() function calling into
fbcon_init() with a vc_cur_blink_ms value of zero.  This is a
transient condition, as it is later set to a non-zero value.  But, if
the timer happens to expire while the blink rate is zero, it goes into
an endless loop, and we get soft lockup.

The fix is to initialize vc_cur_blink_ms before calling the con_init()
function.

Signed-off-by: David Daney <[email protected]>
Cc: [email protected]
Acked-by: Pavel Machek <[email protected]>
Tested-by: Ming Lei <[email protected]>
Acked-by: Scot Doyle <[email protected]>
Tested-by: Henrique de Moraes Holschuh <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index dc125322f48f9d8c958ff09ce6e0406e77d48882..5b0fe97c46ca9fb0bff6b66e0638226bf1b5781d 100644 (file)
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -750,6 +750,7 @@ static void visual_init(struct vc_data *vc, int num, int init)
        vc->vc_complement_mask = 0;
        vc->vc_can_do_color = 0;
        vc->vc_panic_force_write = false;
+       vc->vc_cur_blink_ms = DEFAULT_CURSOR_BLINK_MS;
        vc->vc_sw->con_init(vc, init);
        if (!vc->vc_complement_mask)
                vc->vc_complement_mask = vc->vc_can_do_color ? 0x7700 : 0x0800;