Johannes Engel wrote:
Thomas Hellström wrote:
Yes, this bug could occur, but the remedy is not to use
spin_lock_irqsave() for lock_data::spinlock but to avoid calling
drm_lock_take with the drm_device::tasklet_lock held with irqs disabled.
I'll see if I can come up with a patch.
Hi Thomas,
any news on that so far?
Cheers, Johannes
Hi!
Been on vacation.
Pls try the attached patch.
/Thomas
>From af12ef4f6b4ca111d9a2ef45263ad89610498724 Mon Sep 17 00:00:00 2001
From: Thomas Hellstrom <thomas-at-tungstengraphics-dot-com>
Date: Wed, 13 Aug 2008 10:04:21 +0200
Subject: [PATCH] Don't call the vblank tasklet with irqs disabled.
If a specific tasklet shares data with irq context,
it needs to take a private irq-blocking spinlock within
the tasklet itself.
Signed-off-by: Thomas Hellstrom <thomas-at-tungstengraphics-dot-com>
---
linux-core/drm_irq.c | 20 ++++++++++++--------
linux-core/drm_lock.c | 12 +++++-------
2 files changed, 17 insertions(+), 15 deletions(-)
diff --git a/linux-core/drm_irq.c b/linux-core/drm_irq.c
index 5b9f474..57419ca 100644
--- a/linux-core/drm_irq.c
+++ b/linux-core/drm_irq.c
@@ -705,27 +705,31 @@ static void drm_locked_tasklet_func(unsigned long data)
{
struct drm_device *dev = (struct drm_device *)data;
unsigned long irqflags;
-
+ void (*tasklet_func)(struct drm_device *);
+
spin_lock_irqsave(&dev->tasklet_lock, irqflags);
+ tasklet_func = dev->locked_tasklet_func;
+ spin_unlock_irqrestore(&dev->tasklet_lock, irqflags);
- if (!dev->locked_tasklet_func ||
+ if (!tasklet_func ||
!drm_lock_take(&dev->lock,
DRM_KERNEL_CONTEXT)) {
- spin_unlock_irqrestore(&dev->tasklet_lock, irqflags);
return;
}
dev->lock.lock_time = jiffies;
atomic_inc(&dev->counts[_DRM_STAT_LOCKS]);
- dev->locked_tasklet_func(dev);
+ spin_lock_irqsave(&dev->tasklet_lock, irqflags);
+ tasklet_func = dev->locked_tasklet_func;
+ dev->locked_tasklet_func = NULL;
+ spin_unlock_irqrestore(&dev->tasklet_lock, irqflags);
+
+ if (tasklet_func != NULL)
+ tasklet_func(dev);
drm_lock_free(&dev->lock,
DRM_KERNEL_CONTEXT);
-
- dev->locked_tasklet_func = NULL;
-
- spin_unlock_irqrestore(&dev->tasklet_lock, irqflags);
}
/**
diff --git a/linux-core/drm_lock.c b/linux-core/drm_lock.c
index a2966ef..cad2e44 100644
--- a/linux-core/drm_lock.c
+++ b/linux-core/drm_lock.c
@@ -155,6 +155,7 @@ int drm_unlock(struct drm_device *dev, void *data, struct
drm_file *file_priv)
{
struct drm_lock *lock = data;
unsigned long irqflags;
+ void (*tasklet_func)(struct drm_device *);
if (lock->context == DRM_KERNEL_CONTEXT) {
DRM_ERROR("Process %d using kernel context %d\n",
@@ -163,14 +164,11 @@ int drm_unlock(struct drm_device *dev, void *data, struct
drm_file *file_priv)
}
spin_lock_irqsave(&dev->tasklet_lock, irqflags);
-
- if (dev->locked_tasklet_func) {
- dev->locked_tasklet_func(dev);
-
- dev->locked_tasklet_func = NULL;
- }
-
+ tasklet_func = dev->locked_tasklet_func;
+ dev->locked_tasklet_func = NULL;
spin_unlock_irqrestore(&dev->tasklet_lock, irqflags);
+ if (tasklet_func != NULL)
+ tasklet_func(dev);
atomic_inc(&dev->counts[_DRM_STAT_UNLOCKS]);
--
1.5.4.3
-------------------------------------------------------------------------
This SF.Net email is sponsored by the Moblin Your Move Developer's challenge
Build the coolest Linux based applications with Moblin SDK & win great prizes
Grand prize is a trip for two to an Open Source event anywhere in the world
http://moblin-contest.org/redirect.php?banner_id=100&url=/
--
_______________________________________________
Dri-devel mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/dri-devel
