* [PATCH] drm/i915: Replace lockless_dereference(bool) with READ_ONCE()
@ 2016-07-05 7:54 Chris Wilson
2016-07-05 8:31 ` ✓ Ro.CI.BAT: success for " Patchwork
2016-07-05 9:54 ` [PATCH] " Mika Kuoppala
0 siblings, 2 replies; 4+ messages in thread
From: Chris Wilson @ 2016-07-05 7:54 UTC (permalink / raw)
To: intel-gfx
After Joonas complained about using READ_ONCE() on the only use of the
variable in the function, where the intent was to simply document that
the read was intentionally racy and unlocked, I switched the READ_ONCE()
over to lockless_dereference(). However, in linux-next that has a
stronger type-check to only allow pointers and is no longer
interchangeable with READ_ONCE(), see commit 331b6d8c7afc
("locking/barriers: Validate lockless_dereference() is used on a pointer
type")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Fixes: 67d97da34917 ("drm/i915: Only start retire worker when idle")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
drivers/gpu/drm/i915/i915_gem.c | 2 +-
drivers/gpu/drm/i915/i915_irq.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index a7852dd0a3d4..20123c09bc18 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3290,7 +3290,7 @@ i915_gem_retire_work_handler(struct work_struct *work)
* We do not need to do this test under locking as in the worst-case
* we queue the retire worker once too often.
*/
- if (lockless_dereference(dev_priv->gt.awake))
+ if (READ_ONCE(dev_priv->gt.awake))
queue_delayed_work(dev_priv->wq,
&dev_priv->gt.retire_work,
round_jiffies_up_relative(HZ));
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index f6de8dd567a2..2f01b0b959a1 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -3095,7 +3095,7 @@ static void i915_hangcheck_elapsed(struct work_struct *work)
if (!i915.enable_hangcheck)
return;
- if (!lockless_dereference(dev_priv->gt.awake))
+ if (!READ_ONCE(dev_priv->gt.awake))
return;
/* As enabling the GPU requires fairly extensive mmio access,
--
2.8.1
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^ permalink raw reply related [flat|nested] 4+ messages in thread* ✓ Ro.CI.BAT: success for drm/i915: Replace lockless_dereference(bool) with READ_ONCE()
2016-07-05 7:54 [PATCH] drm/i915: Replace lockless_dereference(bool) with READ_ONCE() Chris Wilson
@ 2016-07-05 8:31 ` Patchwork
2016-07-05 9:54 ` [PATCH] " Mika Kuoppala
1 sibling, 0 replies; 4+ messages in thread
From: Patchwork @ 2016-07-05 8:31 UTC (permalink / raw)
To: Chris Wilson; +Cc: intel-gfx
== Series Details ==
Series: drm/i915: Replace lockless_dereference(bool) with READ_ONCE()
URL : https://patchwork.freedesktop.org/series/9501/
State : success
== Summary ==
Series 9501v1 drm/i915: Replace lockless_dereference(bool) with READ_ONCE()
http://patchwork.freedesktop.org/api/1.0/series/9501/revisions/1/mbox
Test gem_exec_flush:
Subgroup basic-batch-kernel-default-uc:
dmesg-fail -> PASS (fi-skl-i7-6700k)
Test gem_exec_suspend:
Subgroup basic-s3:
incomplete -> PASS (fi-snb-i7-2600)
Test gem_mmap:
Subgroup basic:
incomplete -> PASS (fi-skl-i7-6700k)
Test kms_cursor_legacy:
Subgroup basic-cursor-vs-flip:
dmesg-warn -> PASS (fi-skl-i5-6260u)
Test kms_pipe_crc_basic:
Subgroup nonblocking-crc-pipe-c-frame-sequence:
skip -> PASS (fi-skl-i5-6260u)
Subgroup read-crc-pipe-b:
skip -> PASS (fi-skl-i5-6260u)
fi-kbl-qkkr total:234 pass:162 dwarn:28 dfail:1 fail:2 skip:41
fi-skl-i5-6260u total:234 pass:206 dwarn:0 dfail:0 fail:2 skip:26
fi-skl-i7-6700k total:234 pass:192 dwarn:0 dfail:0 fail:2 skip:40
fi-snb-i7-2600 total:234 pass:178 dwarn:0 dfail:0 fail:2 skip:54
ro-bdw-i5-5250u total:229 pass:204 dwarn:1 dfail:1 fail:0 skip:23
ro-bdw-i7-5557U total:229 pass:203 dwarn:1 dfail:2 fail:0 skip:23
ro-bdw-i7-5600u total:229 pass:190 dwarn:0 dfail:1 fail:0 skip:38
ro-bsw-n3050 total:229 pass:175 dwarn:0 dfail:2 fail:3 skip:49
ro-byt-n2820 total:229 pass:181 dwarn:0 dfail:1 fail:2 skip:45
ro-hsw-i3-4010u total:229 pass:197 dwarn:0 dfail:1 fail:0 skip:31
ro-hsw-i7-4770r total:229 pass:197 dwarn:0 dfail:1 fail:0 skip:31
ro-ilk-i7-620lm total:22 pass:0 dwarn:7 dfail:0 fail:0 skip:14
ro-ilk1-i5-650 total:224 pass:157 dwarn:0 dfail:1 fail:1 skip:65
ro-ivb-i7-3770 total:229 pass:188 dwarn:0 dfail:1 fail:0 skip:40
ro-skl3-i5-6260u total:229 pass:208 dwarn:1 dfail:1 fail:0 skip:19
ro-snb-i7-2620M total:229 pass:179 dwarn:0 dfail:1 fail:1 skip:48
Results at /archive/results/CI_IGT_test/RO_Patchwork_1409/
0a1ed46 drm-intel-nightly: 2016y-07m-04d-15h-39m-24s UTC integration manifest
23162de drm/i915: Replace lockless_dereference(bool) with READ_ONCE()
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^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] drm/i915: Replace lockless_dereference(bool) with READ_ONCE()
2016-07-05 7:54 [PATCH] drm/i915: Replace lockless_dereference(bool) with READ_ONCE() Chris Wilson
2016-07-05 8:31 ` ✓ Ro.CI.BAT: success for " Patchwork
@ 2016-07-05 9:54 ` Mika Kuoppala
2016-07-05 9:59 ` Chris Wilson
1 sibling, 1 reply; 4+ messages in thread
From: Mika Kuoppala @ 2016-07-05 9:54 UTC (permalink / raw)
To: Chris Wilson, intel-gfx
Chris Wilson <chris@chris-wilson.co.uk> writes:
> After Joonas complained about using READ_ONCE() on the only use of the
> variable in the function, where the intent was to simply document that
> the read was intentionally racy and unlocked, I switched the READ_ONCE()
> over to lockless_dereference(). However, in linux-next that has a
> stronger type-check to only allow pointers and is no longer
> interchangeable with READ_ONCE(), see commit 331b6d8c7afc
> ("locking/barriers: Validate lockless_dereference() is used on a pointer
> type")
>
> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
> Fixes: 67d97da34917 ("drm/i915: Only start retire worker when idle")
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
> ---
> drivers/gpu/drm/i915/i915_gem.c | 2 +-
> drivers/gpu/drm/i915/i915_irq.c | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index a7852dd0a3d4..20123c09bc18 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -3290,7 +3290,7 @@ i915_gem_retire_work_handler(struct work_struct *work)
> * We do not need to do this test under locking as in the worst-case
> * we queue the retire worker once too often.
> */
> - if (lockless_dereference(dev_priv->gt.awake))
> + if (READ_ONCE(dev_priv->gt.awake))
> queue_delayed_work(dev_priv->wq,
> &dev_priv->gt.retire_work,
> round_jiffies_up_relative(HZ));
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index f6de8dd567a2..2f01b0b959a1 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -3095,7 +3095,7 @@ static void i915_hangcheck_elapsed(struct work_struct *work)
> if (!i915.enable_hangcheck)
> return;
>
> - if (!lockless_dereference(dev_priv->gt.awake))
> + if (!READ_ONCE(dev_priv->gt.awake))
> return;
>
> /* As enabling the GPU requires fairly extensive mmio access,
> --
> 2.8.1
>
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
_______________________________________________
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Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] drm/i915: Replace lockless_dereference(bool) with READ_ONCE()
2016-07-05 9:54 ` [PATCH] " Mika Kuoppala
@ 2016-07-05 9:59 ` Chris Wilson
0 siblings, 0 replies; 4+ messages in thread
From: Chris Wilson @ 2016-07-05 9:59 UTC (permalink / raw)
To: Mika Kuoppala; +Cc: intel-gfx
On Tue, Jul 05, 2016 at 12:54:50PM +0300, Mika Kuoppala wrote:
> Chris Wilson <chris@chris-wilson.co.uk> writes:
>
> > After Joonas complained about using READ_ONCE() on the only use of the
> > variable in the function, where the intent was to simply document that
> > the read was intentionally racy and unlocked, I switched the READ_ONCE()
> > over to lockless_dereference(). However, in linux-next that has a
> > stronger type-check to only allow pointers and is no longer
> > interchangeable with READ_ONCE(), see commit 331b6d8c7afc
> > ("locking/barriers: Validate lockless_dereference() is used on a pointer
> > type")
> >
> > Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
> > Fixes: 67d97da34917 ("drm/i915: Only start retire worker when idle")
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>
> Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Ta, though if PeterZ complains more about superfluous use of data
dependency barriers we may have to invent our own documentatary macro.
-Chris
>
--
Chris Wilson, Intel Open Source Technology Centre
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^ permalink raw reply [flat|nested] 4+ messages in thread
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2016-07-05 7:54 [PATCH] drm/i915: Replace lockless_dereference(bool) with READ_ONCE() Chris Wilson
2016-07-05 8:31 ` ✓ Ro.CI.BAT: success for " Patchwork
2016-07-05 9:54 ` [PATCH] " Mika Kuoppala
2016-07-05 9:59 ` Chris Wilson
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