From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Reding Date: Wed, 27 May 2015 12:39:40 +0000 Subject: Re: [PATCH] fbcon: Avoid deleting a timer in IRQ context Message-Id: <20150527123938.GA11999@ulmo.nvidia.com> MIME-Version: 1 Content-Type: multipart/mixed; boundary="bg08WKrSYDhXBjb5" List-Id: References: <1432195083-25005-1-git-send-email-thierry.reding@gmail.com> In-Reply-To: <1432195083-25005-1-git-send-email-thierry.reding@gmail.com> To: Greg Kroah-Hartman Cc: Kevin Hilman , Scot Doyle , Daniel Stone , Jean-Christophe Plagniol-Villard , Tomi Valkeinen , linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org --bg08WKrSYDhXBjb5 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, May 21, 2015 at 09:58:03AM +0200, Thierry Reding wrote: > From: Thierry Reding >=20 > 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=3DttyS0 console=3Dtty1" 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: >=20 > [ 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+0x1= c/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/0x= 180) > [ 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.const= prop.23+0xc8/0xec) > [ 5.070218] [] (call_console_drivers.constprop.23) from [] (console_u= nlock+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) >=20 > After which the system starts spewing all kinds of weird and seemingly > unrelated error messages. >=20 > This commit fixes this by restoring the condition under which the call > to fbcon_del_cursor_timer() happens. >=20 > 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 >=20 > 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 mo= de) > return; > =20 > ops->cur_blink_jiffies =3D 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); > =20 > ops->cursor_flash =3D (mode =3D=3D CM_ERASE) ? 0 : 1; > --=20 > 2.4.1 >=20 --bg08WKrSYDhXBjb5 Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAABCAAGBQJVZbsDAAoJEN0jrNd/PrOhuioP/10TJHbBvKNVHYzePa2Wb1oP G0LXQGjlmnj1gJim3LnQ7bpXEG3YFXrbUkzHFfBXh3zZ5aMzeGyZDJQ1W3jsSI1M +HlvwxPUn2eb00+DxyzVxSLx7WixFmQAL76Pw06QBEbdH/JT1ewqEdl8NsPEK0Gm hflZ/aDnq2w7oWQ/DXXIjQ2PIosTccy9LMM5lYpsxnLkmvxxvQBmaxg9iU49/Y5g cKM/BUeBV0iQAmAW8hO5ar/elEDY33DKY0s/y0Zo3n5DaGWwdvRx4wcuJryyGgES tBPymj13Bx23Ox3GWLqNb1t44mmZL6zX29JqsVHaJnefDq+SkSypF8f2JccTrNxl DwL+M0V7KeQeQAVSfuJPM76H1joFX0bgnVdFcCqxLycVvjwcMhL9/ewBe+wKoz59 W51ZmMKlLpIjdYnNtJLk0uQ6uSSHGDHNd+zfgKw5Qkh8y5x89KEF+pcElyVVzXB9 R3zSNpPl3r8UpZCRbvOo9mkBP222kZq2CuWqa/iwJhzF+Sj3P4jrs36tNJkHw2Zl gf8/0XhpnKRNaMRFNsg5lNvnNikgEmnC0saR6oFxdKiR34bdJSHjEn0SuMn5Y3Qe hHPfWHstQDuGZtFBIahAralv8LfDhdkTBGbrtuJI+js7APVbLr7s0VR2z7/mZ6xV 45bjZgb5Ijbd4qrlVdfE =LY63 -----END PGP SIGNATURE----- --bg08WKrSYDhXBjb5--