spin_is_locked() always returns false in uniprocessor configurations and can therefore not be used with BUG_ON. Replace it with assert_spin_locked(), which exists for that very purpose.
Signed-off-by: Guenter Roeck linux@roeck-us.net --- drivers/gpu/drm/msm/mdp/mdp_kms.c | 2 +- drivers/gpu/drm/nouveau/core/core/event.c | 4 ++-- drivers/gpu/drm/nouveau/core/core/notify.c | 2 +- drivers/gpu/drm/omapdrm/omap_irq.c | 2 +- 4 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/msm/mdp/mdp_kms.c b/drivers/gpu/drm/msm/mdp/mdp_kms.c index 03455b6..92a1531 100644 --- a/drivers/gpu/drm/msm/mdp/mdp_kms.c +++ b/drivers/gpu/drm/msm/mdp/mdp_kms.c @@ -34,7 +34,7 @@ static void update_irq(struct mdp_kms *mdp_kms) struct mdp_irq *irq; uint32_t irqmask = mdp_kms->vblank_mask;
- BUG_ON(!spin_is_locked(&list_lock)); + assert_spin_locked(&list_lock);
list_for_each_entry(irq, &mdp_kms->irq_list, node) irqmask |= irq->irqmask; diff --git a/drivers/gpu/drm/nouveau/core/core/event.c b/drivers/gpu/drm/nouveau/core/core/event.c index 0540a48..9327117 100644 --- a/drivers/gpu/drm/nouveau/core/core/event.c +++ b/drivers/gpu/drm/nouveau/core/core/event.c @@ -26,7 +26,7 @@ void nvkm_event_put(struct nvkm_event *event, u32 types, int index) { - BUG_ON(!spin_is_locked(&event->refs_lock)); + assert_spin_locked(&event->refs_lock); while (types) { int type = __ffs(types); types &= ~(1 << type); if (--event->refs[index * event->types_nr + type] == 0) { @@ -39,7 +39,7 @@ nvkm_event_put(struct nvkm_event *event, u32 types, int index) void nvkm_event_get(struct nvkm_event *event, u32 types, int index) { - BUG_ON(!spin_is_locked(&event->refs_lock)); + assert_spin_locked(&event->refs_lock); while (types) { int type = __ffs(types); types &= ~(1 << type); if (++event->refs[index * event->types_nr + type] == 1) { diff --git a/drivers/gpu/drm/nouveau/core/core/notify.c b/drivers/gpu/drm/nouveau/core/core/notify.c index 76adb81..f70dbc4 100644 --- a/drivers/gpu/drm/nouveau/core/core/notify.c +++ b/drivers/gpu/drm/nouveau/core/core/notify.c @@ -98,7 +98,7 @@ nvkm_notify_send(struct nvkm_notify *notify, void *data, u32 size) struct nvkm_event *event = notify->event; unsigned long flags;
- BUG_ON(!spin_is_locked(&event->list_lock)); + assert_spin_locked(&event->list_lock); BUG_ON(size != notify->size);
spin_lock_irqsave(&event->refs_lock, flags); diff --git a/drivers/gpu/drm/omapdrm/omap_irq.c b/drivers/gpu/drm/omapdrm/omap_irq.c index f035d2b..3eb097e 100644 --- a/drivers/gpu/drm/omapdrm/omap_irq.c +++ b/drivers/gpu/drm/omapdrm/omap_irq.c @@ -34,7 +34,7 @@ static void omap_irq_update(struct drm_device *dev) struct omap_drm_irq *irq; uint32_t irqmask = priv->vblank_mask;
- BUG_ON(!spin_is_locked(&list_lock)); + assert_spin_locked(&list_lock);
list_for_each_entry(irq, &priv->irq_list, node) irqmask |= irq->irqmask;
Hello Roeck,
This should be replaced everywhere in driver.what do you say ?
Regards Sanjeev Sharma
On Mon, Aug 11, 2014 at 10:01 AM, Guenter Roeck linux@roeck-us.net wrote:
spin_is_locked() always returns false in uniprocessor configurations and can therefore not be used with BUG_ON. Replace it with assert_spin_locked(), which exists for that very purpose.
Signed-off-by: Guenter Roeck linux@roeck-us.net
drivers/gpu/drm/msm/mdp/mdp_kms.c | 2 +- drivers/gpu/drm/nouveau/core/core/event.c | 4 ++-- drivers/gpu/drm/nouveau/core/core/notify.c | 2 +- drivers/gpu/drm/omapdrm/omap_irq.c | 2 +- 4 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/msm/mdp/mdp_kms.c b/drivers/gpu/drm/msm/mdp/mdp_kms.c index 03455b6..92a1531 100644 --- a/drivers/gpu/drm/msm/mdp/mdp_kms.c +++ b/drivers/gpu/drm/msm/mdp/mdp_kms.c @@ -34,7 +34,7 @@ static void update_irq(struct mdp_kms *mdp_kms) struct mdp_irq *irq; uint32_t irqmask = mdp_kms->vblank_mask;
BUG_ON(!spin_is_locked(&list_lock));
assert_spin_locked(&list_lock); list_for_each_entry(irq, &mdp_kms->irq_list, node) irqmask |= irq->irqmask;diff --git a/drivers/gpu/drm/nouveau/core/core/event.c b/drivers/gpu/drm/nouveau/core/core/event.c index 0540a48..9327117 100644 --- a/drivers/gpu/drm/nouveau/core/core/event.c +++ b/drivers/gpu/drm/nouveau/core/core/event.c @@ -26,7 +26,7 @@ void nvkm_event_put(struct nvkm_event *event, u32 types, int index) {
BUG_ON(!spin_is_locked(&event->refs_lock));
assert_spin_locked(&event->refs_lock); while (types) { int type = __ffs(types); types &= ~(1 << type); if (--event->refs[index * event->types_nr + type] == 0) {@@ -39,7 +39,7 @@ nvkm_event_put(struct nvkm_event *event, u32 types, int index) void nvkm_event_get(struct nvkm_event *event, u32 types, int index) {
BUG_ON(!spin_is_locked(&event->refs_lock));
assert_spin_locked(&event->refs_lock); while (types) { int type = __ffs(types); types &= ~(1 << type); if (++event->refs[index * event->types_nr + type] == 1) {diff --git a/drivers/gpu/drm/nouveau/core/core/notify.c b/drivers/gpu/drm/nouveau/core/core/notify.c index 76adb81..f70dbc4 100644 --- a/drivers/gpu/drm/nouveau/core/core/notify.c +++ b/drivers/gpu/drm/nouveau/core/core/notify.c @@ -98,7 +98,7 @@ nvkm_notify_send(struct nvkm_notify *notify, void *data, u32 size) struct nvkm_event *event = notify->event; unsigned long flags;
BUG_ON(!spin_is_locked(&event->list_lock));
assert_spin_locked(&event->list_lock); BUG_ON(size != notify->size); spin_lock_irqsave(&event->refs_lock, flags);diff --git a/drivers/gpu/drm/omapdrm/omap_irq.c b/drivers/gpu/drm/omapdrm/omap_irq.c index f035d2b..3eb097e 100644 --- a/drivers/gpu/drm/omapdrm/omap_irq.c +++ b/drivers/gpu/drm/omapdrm/omap_irq.c @@ -34,7 +34,7 @@ static void omap_irq_update(struct drm_device *dev) struct omap_drm_irq *irq; uint32_t irqmask = priv->vblank_mask;
BUG_ON(!spin_is_locked(&list_lock));
assert_spin_locked(&list_lock); list_for_each_entry(irq, &priv->irq_list, node) irqmask |= irq->irqmask;-- 1.9.1
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On Sun, 10 Aug 2014, Guenter Roeck wrote:
spin_is_locked() always returns false in uniprocessor configurations and can therefore not be used with BUG_ON. Replace it with assert_spin_locked(), which exists for that very purpose.
It may be helpful to assess whether any of these sites should be converted to lockdep_assert_held() so they have no cost when lockdep isn't enabled but still reveal problems when debugging.
Hello David,
Do you see any problem in replacing with assert_spin_locked() and here is old discusion around the
On Mon, Aug 11, 2014 at 5:15 PM, David Rientjes rientjes@google.com wrote:
On Sun, 10 Aug 2014, Guenter Roeck wrote:
spin_is_locked() always returns false in uniprocessor configurations and can therefore not be used with BUG_ON. Replace it with assert_spin_locked(), which exists for that very purpose.
It may be helpful to assess whether any of these sites should be converted to lockdep_assert_held() so they have no cost when lockdep isn't enabled but still reveal problems when debugging. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Hello David,
Here is the old discussion carried out on this.
http://linux-kernel.2935.n7.nabble.com/Is-spin-is-locked-safe-to-use-with-BU...
Regards Sanjeev Sharma
On Mon, Aug 11, 2014 at 5:31 PM, sanjeev sharma <sanjeevsharmaengg@gmail.com
wrote:
Hello David,
Do you see any problem in replacing with assert_spin_locked() and here is old discusion around the
On Mon, Aug 11, 2014 at 5:15 PM, David Rientjes rientjes@google.com wrote:
On Sun, 10 Aug 2014, Guenter Roeck wrote:
spin_is_locked() always returns false in uniprocessor configurations and can therefore not be used with BUG_ON. Replace it with assert_spin_locked(), which exists for that very purpose.
It may be helpful to assess whether any of these sites should be converted to lockdep_assert_held() so they have no cost when lockdep isn't enabled but still reveal problems when debugging. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
On Mon, 11 Aug 2014, sanjeev sharma wrote:
Hello David,
Here is the old discussion carried out on this.
http://linux-kernel.2935.n7.nabble.com/Is-spin-is-locked-safe-to-use-with-BU...
I'm suggesting that if you don't want to incur the cost of the conditional everytime you call a certain function with assert_spin_locked() that you could covert these to lockdep_assert_held() so the check is only done when lockdep is enabled for debugging.
On Mon, Aug 11, 2014 at 4:53 PM, David Rientjes rientjes@google.com wrote:
On Mon, 11 Aug 2014, sanjeev sharma wrote:
Hello David,
Here is the old discussion carried out on this.
http://linux-kernel.2935.n7.nabble.com/Is-spin-is-locked-safe-to-use-with-BU...
I'm suggesting that if you don't want to incur the cost of the conditional everytime you call a certain function with assert_spin_locked() that you could covert these to lockdep_assert_held() so the check is only done when lockdep is enabled for debugging.
not sure about the nouveau parts, but for the omap and msm hunks, this code getting called at potentially vblank rate (so maybe once or twice per ~16ms).. and lockdep has considerable overhead (for a gpu driver) so I don't always have it enabled. So it sounds like for those two at least assert_spin_locked() is a better option.
BR, -R
dri-devel mailing list dri-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/dri-devel
On Mon, 11 Aug 2014, Rob Clark wrote:
I'm suggesting that if you don't want to incur the cost of the conditional everytime you call a certain function with assert_spin_locked() that you could covert these to lockdep_assert_held() so the check is only done when lockdep is enabled for debugging.
not sure about the nouveau parts, but for the omap and msm hunks, this code getting called at potentially vblank rate (so maybe once or twice per ~16ms).. and lockdep has considerable overhead (for a gpu driver) so I don't always have it enabled. So it sounds like for those two at least assert_spin_locked() is a better option.
Unless there's a bug, assert_spin_locked() is just going to incur an unnecessary cost every time it is called at runtime. My suggestion was to limit that check only to debugging kernels that include enabling lockdep when tracking down problems rather than needlessly evaluating the conditional every time when there are no bugs.
Thanks all and I replaced with lockdep_assert_held() which seems less overhead.
Regards Sanjeev Sharma
On Tue, Aug 12, 2014 at 5:08 AM, David Rientjes rientjes@google.com wrote:
On Mon, 11 Aug 2014, Rob Clark wrote:
I'm suggesting that if you don't want to incur the cost of the
conditional
everytime you call a certain function with assert_spin_locked() that
you
could covert these to lockdep_assert_held() so the check is only done
when
lockdep is enabled for debugging.
not sure about the nouveau parts, but for the omap and msm hunks, this code getting called at potentially vblank rate (so maybe once or twice per ~16ms).. and lockdep has considerable overhead (for a gpu driver) so I don't always have it enabled. So it sounds like for those two at least assert_spin_locked() is a better option.
Unless there's a bug, assert_spin_locked() is just going to incur an unnecessary cost every time it is called at runtime. My suggestion was to limit that check only to debugging kernels that include enabling lockdep when tracking down problems rather than needlessly evaluating the conditional every time when there are no bugs.
On Mon, Aug 11, 2014 at 04:38:50PM -0700, David Rientjes wrote:
On Mon, 11 Aug 2014, Rob Clark wrote:
I'm suggesting that if you don't want to incur the cost of the conditional everytime you call a certain function with assert_spin_locked() that you could covert these to lockdep_assert_held() so the check is only done when lockdep is enabled for debugging.
not sure about the nouveau parts, but for the omap and msm hunks, this code getting called at potentially vblank rate (so maybe once or twice per ~16ms).. and lockdep has considerable overhead (for a gpu driver) so I don't always have it enabled. So it sounds like for those two at least assert_spin_locked() is a better option.
Unless there's a bug, assert_spin_locked() is just going to incur an unnecessary cost every time it is called at runtime. My suggestion was to limit that check only to debugging kernels that include enabling lockdep when tracking down problems rather than needlessly evaluating the conditional every time when there are no bugs.
My experience with gpu drivers (i915) has been that hw and the software running it is varied enough that almost always it's better to unconditionally enable this stuff. I much prefer assert_spin_locked and friends over the lockdep versions since enabling full lockdep is not something you usually do. Especially not normal users, and we rely upon them for testing the old stuff. Furthermore for the modeset code the overhead is totally irrelevant since we're doing metric piles of register reads and writes in there anyway. -Daniel
yes you are absolutely correct and the change I have done in other area i.e drivers/usb/storage/uas.c.In gpu drivers assert_spin_locked() make more sense.
Regards Sanjeev Sharma
On Tue, Aug 12, 2014 at 12:25 PM, Daniel Vetter daniel@ffwll.ch wrote:
On Mon, Aug 11, 2014 at 04:38:50PM -0700, David Rientjes wrote:
On Mon, 11 Aug 2014, Rob Clark wrote:
I'm suggesting that if you don't want to incur the cost of the
conditional
everytime you call a certain function with assert_spin_locked() that
you
could covert these to lockdep_assert_held() so the check is only
done when
lockdep is enabled for debugging.
not sure about the nouveau parts, but for the omap and msm hunks, this code getting called at potentially vblank rate (so maybe once or twice per ~16ms).. and lockdep has considerable overhead (for a gpu driver) so I don't always have it enabled. So it sounds like for those two at least assert_spin_locked() is a better option.
Unless there's a bug, assert_spin_locked() is just going to incur an unnecessary cost every time it is called at runtime. My suggestion was
to
limit that check only to debugging kernels that include enabling lockdep when tracking down problems rather than needlessly evaluating the conditional every time when there are no bugs.
My experience with gpu drivers (i915) has been that hw and the software running it is varied enough that almost always it's better to unconditionally enable this stuff. I much prefer assert_spin_locked and friends over the lockdep versions since enabling full lockdep is not something you usually do. Especially not normal users, and we rely upon them for testing the old stuff. Furthermore for the modeset code the overhead is totally irrelevant since we're doing metric piles of register reads and writes in there anyway.
-Daniel
Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch
ssert_spin_locked() is a better option.
Unless there's a bug, assert_spin_locked() is just going to incur an unnecessary cost every time it is called at runtime. My suggestion was to limit that check only to debugging kernels that include enabling lockdep when tracking down problems rather than needlessly evaluating the conditional every time when there are no bugs.
My experience with gpu drivers (i915) has been that hw and the software running it is varied enough that almost always it's better to unconditionally enable this stuff. I much prefer assert_spin_locked and friends over the lockdep versions since enabling full lockdep is not something you usually do. Especially not normal users, and we rely upon them for testing the old stuff. Furthermore for the modeset code the overhead is totally irrelevant since we're doing metric piles of register reads and writes in there anyway.
Did anything translate into an R-b here?
Dave.
On 08/11/2014 04:45 AM, David Rientjes wrote:
On Sun, 10 Aug 2014, Guenter Roeck wrote:
spin_is_locked() always returns false in uniprocessor configurations and can therefore not be used with BUG_ON. Replace it with assert_spin_locked(), which exists for that very purpose.
It may be helpful to assess whether any of these sites should be converted to lockdep_assert_held() so they have no cost when lockdep isn't enabled but still reveal problems when debugging.
Possibly, but that would need to be done by someone with better knowledge about locking and the code than me.
Guenter
dri-devel@lists.freedesktop.org
-
Daniel Vetter -
Dave Airlie -
David Rientjes -
Guenter Roeck -
Rob Clark -
sanjeev sharma