On Fri, Jul 25, 2008 at 6:42 PM, Jiri Slaby <[EMAIL PROTECTED]> wrote:
> 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).
Hmm this has bounced through 2-3 variations.. Thomas any ideas what
the final correct answer is?
Dave.
>
> 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:
> <IRQ> [<ffffffff8023813f>] warn_on_slowpath+0x5f/0x90
> [...]
> [<ffffffff8023e1fb>] local_bh_enable_ip+0x8b/0xb0
> [<ffffffff8055b2cf>] _spin_unlock_bh+0xf/0x20
> [<ffffffff803b0bd1>] drm_lock_take+0x81/0xe0
> [<ffffffff803b006b>] drm_locked_tasklet_func+0x4b/0xb0
> [<ffffffff8023daf9>] tasklet_hi_action+0x69/0xf0
> [<ffffffff8023e3e4>] __do_softirq+0x84/0xf0
> [stack snipped]
>
> Signed-off-by: Jiri Slaby <[EMAIL PROTECTED]>
> Cc: David Airlie <[EMAIL PROTECTED]>
> ---
> 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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