Add patch from Dave Airlie to fix fb cursor vs grub2 gfxterm hang

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 00000000..992bd252
--- /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@redhat.com>

+To: linux-fbdev@vger.kernel.org

+Cc: dri-devel@lists.sf.net, linux-kernel@vger.kernel.org,

+        Linus <torvalds@linux-foundation.org>,

+        Alan Cox <alan@lxorguk.ukuu.org.uk>,

+        Randy Dunlap <rdunlap@xenotime.net>, Josh Boyer <jwboyer@gmail.com>,

+        Dave Airlie <airlied@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@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@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 05f65d2c..39edbfe8 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@redhat.com>
+- Add patch from Dave Airlie to fix fb cursor vs grub2 gfxterm hang
+
 * Mon Aug 20 2012 Josh Boyer <jwboyer@redhat.com> - 3.6.0-0.rc2.git1.1
 - Linux v3.6-rc2-206-g10c63c9