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authorThierry Reding <treding@nvidia.com>2015-05-21 09:58:03 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-05-27 05:55:38 -0700
commita5edce42184844239bc209c727435654cd0b5f2d (patch)
treeae3a70d1706766a5ee632df58de8fbbf1d10ccb7 /drivers/video/console
parent3db9ab0b6d8a293435a78c048f877099e040f72c (diff)
downloadop-kernel-dev-a5edce42184844239bc209c727435654cd0b5f2d.zip
op-kernel-dev-a5edce42184844239bc209c727435654cd0b5f2d.tar.gz
fbcon: Avoid deleting a timer in IRQ context
Commit 27a4c827c34a ("fbcon: use the cursor blink interval provided by vt") unconditionally removes the cursor blink timer. Unfortunately that wreaks havoc under some circumstances. An easily reproducible way is to use both the framebuffer console and a debug serial port as the console output for kernel messages (e.g. "console=ttyS0 console=tty1" on the kernel command-line. Upon boot this triggers a warning from within the del_timer_sync() function because it is called from IRQ context: [ 5.070096] ------------[ cut here ]------------ [ 5.070110] WARNING: CPU: 0 PID: 0 at ../kernel/time/timer.c:1098 del_timer_sync+0x4c/0x54() [ 5.070115] Modules linked in: [ 5.070120] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.1.0-rc4-next-20150519 #1 [ 5.070123] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree) [ 5.070142] [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [ 5.070156] [] (show_stack) from [] (dump_stack+0x70/0xbc) [ 5.070164] [] (dump_stack) from [] (warn_slowpath_common+0x74/0xb0) [ 5.070169] [] (warn_slowpath_common) from [] (warn_slowpath_null+0x1c/0x24) [ 5.070174] [] (warn_slowpath_null) from [] (del_timer_sync+0x4c/0x54) [ 5.070183] [] (del_timer_sync) from [] (fbcon_del_cursor_timer+0x2c/0x40) [ 5.070190] [] (fbcon_del_cursor_timer) from [] (fbcon_cursor+0x9c/0x180) [ 5.070198] [] (fbcon_cursor) from [] (hide_cursor+0x30/0x98) [ 5.070204] [] (hide_cursor) from [] (vt_console_print+0x2a8/0x340) [ 5.070212] [] (vt_console_print) from [] (call_console_drivers.constprop.23+0xc8/0xec) [ 5.070218] [] (call_console_drivers.constprop.23) from [] (console_unlock+0x498/0x4f0) [ 5.070223] [] (console_unlock) from [] (vprintk_emit+0x1f0/0x508) [ 5.070228] [] (vprintk_emit) from [] (vprintk_default+0x24/0x2c) [ 5.070234] [] (vprintk_default) from [] (printk+0x70/0x88) After which the system starts spewing all kinds of weird and seemingly unrelated error messages. This commit fixes this by restoring the condition under which the call to fbcon_del_cursor_timer() happens. Reported-by: Daniel Stone <daniel@fooishbar.org> Reported-by: Kevin Hilman <khilman@kernel.org> Tested-by: Kevin Hilman <khilman@linaro.org> Tested-by: Scot Doyle <lkml14@scotdoyle.com> Signed-off-by: Thierry Reding <treding@nvidia.com> Tested-by: Andrew Vagin <avagin@virtuozzo.com> Tested-by: Tomeu Vizoso <tomeu.vizoso@collabora.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/video/console')
-rw-r--r--drivers/video/console/fbcon.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c
index 05b1d1a..658c34b 100644
--- a/drivers/video/console/fbcon.c
+++ b/drivers/video/console/fbcon.c
@@ -1310,8 +1310,9 @@ static void fbcon_cursor(struct vc_data *vc, int mode)
return;
ops->cur_blink_jiffies = msecs_to_jiffies(vc->vc_cur_blink_ms);
- fbcon_del_cursor_timer(info);
- if (!(vc->vc_cursor_type & 0x10))
+ if (vc->vc_cursor_type & 0x10)
+ fbcon_del_cursor_timer(info);
+ else
fbcon_add_cursor_timer(info);
ops->cursor_flash = (mode == CM_ERASE) ? 0 : 1;
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