drm_lock_take(); and drm_lock_free(); are called from
drm_locked_tasklet_func(); which disables interrupts when grabbing its
spinlock.

Don't allow these locking functions to re-enable interrupts when
the tasklet expects them disabled. I.e. use spin_lock_irqsave instead of
spin_lock_bh (with their unlock opposites).

We will get such a warnings otherwise:
------------[ cut here ]------------
WARNING: at kernel/softirq.c:136 local_bh_enable_ip+0x8b/0xb0()
Modules linked in: arc4 ecb crypto_blkcipher cryptomgr crypto_algapi ath5k usbhid mac80211 ohci1394 hid led_class floppy cfg80211 ff_memless ieee1394 rtc_cmos evdev [last unloaded: freq_table]
Pid: 0, comm: swapper Not tainted 2.6.26-rc8-mm1_64 #427

Call Trace:
[] warn_on_slowpath+0x5f/0x90
[...]
[] local_bh_enable_ip+0x8b/0xb0
[] _spin_unlock_bh+0xf/0x20
[] drm_lock_take+0x81/0xe0
[] drm_locked_tasklet_func+0x4b/0xb0
[] tasklet_hi_action+0x69/0xf0
[] __do_softirq+0x84/0xf0
[stack snipped]

Signed-off-by: Jiri Slaby
Cc: David Airlie
---
drivers/gpu/drm/drm_lock.c | 12 +++++++-----
1 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/drm_lock.c b/drivers/gpu/drm/drm_lock.c
index 0998723..79943e4 100644
--- a/drivers/gpu/drm/drm_lock.c
+++ b/drivers/gpu/drm/drm_lock.c
@@ -196,10 +196,11 @@ int drm_unlock(struct drm_device *dev, void *data, struct drm_file *file_priv)
int drm_lock_take(struct drm_lock_data *lock_data,
unsigned int context)
{
+ unsigned long flags;
unsigned int old, new, prev;
volatile unsigned int *lock = &lock_data->hw_lock->lock;

- spin_lock_bh(&lock_data->spinlock);
+ spin_lock_irqsave(&lock_data->spinlock, flags);
do {
old = *lock;
if (old & _DRM_LOCK_HELD)
@@ -211,7 +212,7 @@ int drm_lock_take(struct drm_lock_data *lock_data,
}
prev = cmpxchg(lock, old, new);
} while (prev != old);
- spin_unlock_bh(&lock_data->spinlock);
+ spin_unlock_irqrestore(&lock_data->spinlock, flags);

if (_DRM_LOCKING_CONTEXT(old) == context) {
if (old & _DRM_LOCK_HELD) {
@@ -270,17 +271,18 @@ static int drm_lock_transfer(struct drm_lock_data *lock_data,
*/
int drm_lock_free(struct drm_lock_data *lock_data, unsigned int context)
{
+ unsigned long flags;
unsigned int old, new, prev;
volatile unsigned int *lock = &lock_data->hw_lock->lock;

- spin_lock_bh(&lock_data->spinlock);
+ spin_lock_irqsave(&lock_data->spinlock, flags);
if (lock_data->kernel_waiters != 0) {
drm_lock_transfer(lock_data, 0);
lock_data->idle_has_lock = 1;
- spin_unlock_bh(&lock_data->spinlock);
+ spin_unlock_irqrestore(&lock_data->spinlock, flags);
return 1;
}
- spin_unlock_bh(&lock_data->spinlock);
+ spin_unlock_irqrestore(&lock_data->spinlock, flags);

do {
old = *lock;
--
1.5.6.2

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