# \[PATCH\] fbcon: Avoid deleting a timer in IRQ context - Subsystems: FRAMEBUFFER LAYER, CONSOLE SUBSYSTEM, THE REST - Maintainers: Helge Deller, Greg Kroah-Hartman, Linus Torvalds - Status: REVIEWED ยท 2 reviews, 0 by maintainers (Kevin Hilman Scot Doyle) - Reviewed. - 2 review trailers. - List: linux-fbdev - 4 messages, 3 authors - Page: https://ratatoskr.run/linux-fbdev/2015/05/4499082/t ## \[PATCH\] fbcon: Avoid deleting a timer in IRQ context - From: Thierry Reding \ - Date: 2015-05-21 07:58:09 - Message: https://ratatoskr.run/linux-fbdev/2015/05/4499082.md ```text From: Thierry Reding 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 Reported-by: Kevin Hilman Tested-by: Kevin Hilman Tested-by: Scot Doyle Signed-off-by: Thierry Reding --- drivers/video/console/fbcon.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c index 05b1d1a71ef9..658c34bb9076 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; -- 2.4.1 ``` ## Re: \[PATCH\] fbcon: Avoid deleting a timer in IRQ context - From: Andrey Wagin \ - Date: 2015-05-27 11:19:07 - Message: https://ratatoskr.run/linux-fbdev/2015/05/4503039.md ```text 2015-05-21 10:58 GMT+03:00 Thierry Reding [ref]: > From: Thierry Reding > > 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. Tested-by: Andrew Vagin It would be good to push this patch into linux-next asap. Without this patch I can't execute tests on linux-next. Thanks. > > Reported-by: Daniel Stone > Reported-by: Kevin Hilman > Tested-by: Kevin Hilman > Tested-by: Scot Doyle > Signed-off-by: Thierry Reding > --- > drivers/video/console/fbcon.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c > index 05b1d1a71ef9..658c34bb9076 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; > -- > 2.4.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ ``` ## Re: \[PATCH\] fbcon: Avoid deleting a timer in IRQ context - From: Tomeu Vizoso \ - Date: 2015-05-27 12:10:28 - Message: https://ratatoskr.run/linux-fbdev/2015/05/4503072.md ```text On 27 May 2015 at 13:19, Andrey Wagin [ref] wrote: > 2015-05-21 10:58 GMT+03:00 Thierry Reding [ref]: >> From: Thierry Reding >> >> 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. > > Tested-by: Andrew Vagin > > It would be good to push this patch into linux-next asap. Without this > patch I can't execute tests on linux-next. Thanks. Tested-by: Tomeu Vizoso Same here, please apply. Thanks, Tomeu >> >> Reported-by: Daniel Stone >> Reported-by: Kevin Hilman >> Tested-by: Kevin Hilman >> Tested-by: Scot Doyle >> Signed-off-by: Thierry Reding >> --- >> drivers/video/console/fbcon.c | 5 +++-- >> 1 file changed, 3 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c >> index 05b1d1a71ef9..658c34bb9076 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; >> -- >> 2.4.1 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> Please read the FAQ at http://www.tux.org/lkml/ > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ ``` ## Re: \[PATCH\] fbcon: Avoid deleting a timer in IRQ context - From: Thierry Reding \ - Date: 2015-05-27 12:39:49 - Message: https://ratatoskr.run/linux-fbdev/2015/05/4503093.md ```text On Thu, May 21, 2015 at 09:58:03AM +0200, Thierry Reding wrote: > From: Thierry Reding > > 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 > Reported-by: Kevin Hilman > Tested-by: Kevin Hilman > Tested-by: Scot Doyle > Signed-off-by: Thierry Reding > --- > drivers/video/console/fbcon.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) Ping? This is an important fix, can we get this into linux-next sometime soon? Thierry > > diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c > index 05b1d1a71ef9..658c34bb9076 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; > -- > 2.4.1 > ```