[kernel] Add patch from Dave Airlie to fix fb cursor vs grub2 gfxterm hang
Josh Boyer
jwboyer at fedoraproject.org
Tue Aug 21 13:32:30 UTC 2012
commit 2875d27c9a977df8cef028fbf82c505f5a7fd712
Author: Josh Boyer <jwboyer at redhat.com>
Date: Tue Aug 21 09:30:44 2012 -0400
Add patch from Dave Airlie to fix fb cursor vs grub2 gfxterm hang
...ion-between-console-lock-and-cursor-timer.patch | 89 ++++++++++++++++++++
kernel.spec | 9 ++-
2 files changed, 97 insertions(+), 1 deletions(-)
---
diff --git a/fbcon-fix-race-condition-between-console-lock-and-cursor-timer.patch b/fbcon-fix-race-condition-between-console-lock-and-cursor-timer.patch
new file mode 100644
index 0000000..992bd25
--- /dev/null
+++ b/fbcon-fix-race-condition-between-console-lock-and-cursor-timer.patch
@@ -0,0 +1,89 @@
+
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+ Tue, 21 Aug 2012 02:40:16 -0400
+From: Dave Airlie <airlied at redhat.com>
+To: linux-fbdev at vger.kernel.org
+Cc: dri-devel at lists.sf.net, linux-kernel at vger.kernel.org,
+ Linus <torvalds at linux-foundation.org>,
+ Alan Cox <alan at lxorguk.ukuu.org.uk>,
+ Randy Dunlap <rdunlap at xenotime.net>, Josh Boyer <jwboyer at gmail.com>,
+ Dave Airlie <airlied at redhat.com>
+Subject: [PATCH] fbcon: fix race condition between console lock and cursor timer
+Date: Tue, 21 Aug 2012 16:40:07 +1000
+Message-Id: <1345531207-24926-1-git-send-email-airlied at redhat.com>
+X-Scanned-By: MIMEDefang 2.67 on 10.5.11.11
+
+So we've had a fair few reports of fbcon handover breakage between
+efi/vesafb and i915 surface recently, so I dedicated a couple of
+days to finding the problem.
+
+Essentially the last thing we saw was the conflicting framebuffer
+message and that was all.
+
+So after much tracing with direct netconsole writes (printks
+under console_lock not so useful), I think I found the race.
+
+Thread A (driver load) Thread B (timer thread)
+ unbind_con_driver -> |
+ bind_con_driver -> |
+ vc->vc_sw->con_deinit -> |
+ fbcon_deinit -> |
+ console_lock() |
+ | |
+ | fbcon_flashcursor timer fires
+ | console_lock() <- blocked for A
+ |
+ |
+fbcon_del_cursor_timer ->
+ del_timer_sync
+ (BOOM)
+
+Of course because all of this is under the console lock,
+we never see anything, also since we also just unbound the active
+console guess what we never see anything.
+
+Hopefully this fixes the problem for anyone seeing vesafb->kms
+driver handoff.
+
+Signed-off-by: David Airlie <airlied at redhat.com>
+---
+ drivers/video/console/fbcon.c | 6 +++++-
+ 1 file changed, 5 insertions(+), 1 deletion(-)
+
+diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c
+index 2e471c2..f8a79fc 100644
+--- a/drivers/video/console/fbcon.c
++++ b/drivers/video/console/fbcon.c
+@@ -372,8 +372,12 @@ static void fb_flashcursor(struct work_struct *work)
+ struct vc_data *vc = NULL;
+ int c;
+ int mode;
++ int ret;
++
++ ret = console_trylock();
++ if (ret == 0)
++ return;
+
+- console_lock();
+ if (ops && ops->currcon != -1)
+ vc = vc_cons[ops->currcon].d;
+
+--
+1.7.10.2
+
diff --git a/kernel.spec b/kernel.spec
index 05f65d2..39edbfe 100644
--- a/kernel.spec
+++ b/kernel.spec
@@ -62,7 +62,7 @@ Summary: The Linux kernel
# For non-released -rc kernels, this will be appended after the rcX and
# gitX tags, so a 3 here would become part of release "0.rcX.gitX.3"
#
-%global baserelease 1
+%global baserelease 2
%global fedora_build %{baserelease}
# base_sublevel is the kernel version we're starting with and patching
@@ -747,6 +747,8 @@ Patch22001: selinux-apply-different-permission-to-ptrace-child.patch
#rhbz 836742
Patch22059: uvcvideo-Reset-bytesused-field-when-recycling-erroneous-buffer.patch
+Patch22065: fbcon-fix-race-condition-between-console-lock-and-cursor-timer.patch
+
# END OF PATCH DEFINITIONS
%endif
@@ -1437,6 +1439,8 @@ ApplyPatch selinux-apply-different-permission-to-ptrace-child.patch
#rhbz 836742
ApplyPatch uvcvideo-Reset-bytesused-field-when-recycling-erroneous-buffer.patch
+ApplyPatch fbcon-fix-race-condition-between-console-lock-and-cursor-timer.patch
+
# END OF PATCH APPLICATIONS
%endif
@@ -2299,6 +2303,9 @@ fi
# ||----w |
# || ||
%changelog
+* Tue Aug 21 2012 Josh Boyer <jwboyer at redhat.com>
+- Add patch from Dave Airlie to fix fb cursor vs grub2 gfxterm hang
+
* Mon Aug 20 2012 Josh Boyer <jwboyer at redhat.com> - 3.6.0-0.rc2.git1.1
- Linux v3.6-rc2-206-g10c63c9
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