]> git.baikalelectronics.ru Git - kernel.git/commit
fbcon: Avoid deleting a timer in IRQ context
authorThierry Reding <treding@nvidia.com>
Thu, 21 May 2015 07:58:03 +0000 (09:58 +0200)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 27 May 2015 12:55:38 +0000 (05:55 -0700)
commit6ee25f60b19fd757c2dfa441c552deb0b15146ca
treeae3a70d1706766a5ee632df58de8fbbf1d10ccb7
parent83b6f496a82f50a77f49894ebf0a8603b9da35c4
fbcon: Avoid deleting a timer in IRQ context

Commit eaa43ff8f0dc ("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>
drivers/video/console/fbcon.c