4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jean-Philippe Brucker <jean-philippe.brucker@xxxxxxx>
commit a1e533ec07d583d01349ef13c0c965b8633e1b91 upstream.
Since commit 27a4c827c34ac4256a190cc9d24607f953c1c459
fbcon: use the cursor blink interval provided by vt
two attempts have been made at fixing a possible hang caused by
cursor_timer_handler. That function registers a timer to be triggered at
"jiffies + fbcon_ops.cur_blink_jiffies".
A new case had been encountered during initialisation of clcd-pl11x:
fbcon_fb_registered
do_fbcon_takeover
-> do_register_con_driver
fbcon_startup
(A) add_cursor_timer (with cur_blink_jiffies = 0)
-> do_bind_con_driver
visual_init
fbcon_init
(B) cur_blink_jiffies = msecs_to_jiffies(vc->vc_cur_blink_ms);
If we take an softirq anywhere between A and B (and we do),
cursor_timer_handler executes indefinitely.
Instead of patching all possible paths that lead to this case one at a
time, fix the issue at the source and initialise cur_blink_jiffies to
200ms when allocating fbcon_ops. This was its default value before
aforesaid commit. fbcon_cursor or fbcon_init will refine this value
downstream.
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@xxxxxxx>
Tested-by: Scot Doyle <lkml14@xxxxxxxxxxxxx>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/video/console/fbcon.c | 2 ++
1 file changed, 2 insertions(+)
--- a/drivers/video/console/fbcon.c
+++ b/drivers/video/console/fbcon.c
@@ -709,6 +709,7 @@ static int con2fb_acquire_newinfo(struct
}
if (!err) {
+ ops->cur_blink_jiffies = HZ / 5;
info->fbcon_par = ops;
if (vc)
@@ -956,6 +957,7 @@ static const char *fbcon_startup(void)
ops->currcon = -1;
ops->graphics = 1;
ops->cur_rotate = -1;
+ ops->cur_blink_jiffies = HZ / 5;
info->fbcon_par = ops;
p->con_rotate = initial_rotation;
set_blitting_type(vc, info);
--
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