Re: [PATCH] drm/vkms: Fix flush_work() without INIT_WORK().

2019-01-25 Thread Daniel Vetter 
On Fri, Jan 25, 2019 at 09:46:15AM -0500, Sean Paul wrote:
> On Sat, Jan 19, 2019 at 01:43:43AM +0900, Tetsuo Handa wrote:
> > syzbot is hitting a lockdep warning [1] because flush_work() is called
> > without INIT_WORK() after kzalloc() at vkms_atomic_crtc_reset().
> > 
> > Commit 6c234fe37c57627a ("drm/vkms: Implement CRC debugfs API") added
> > INIT_WORK() to only vkms_atomic_crtc_duplicate_state() side. Assuming
> > that lifecycle of crc_work is appropriately managed, fix this problem
> > by adding INIT_WORK() to vkms_atomic_crtc_reset() side.
> > 
> > [1] 
> > https://syzkaller.appspot.com/bug?id=a5954455fcfa51c29ca2ab55b203076337e1c770
> > 
> > Reported-and-tested-by: syzbot 
> > 
> > Signed-off-by: Tetsuo Handa 
> > ---
> >  drivers/gpu/drm/vkms/vkms_crtc.c | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c 
> > b/drivers/gpu/drm/vkms/vkms_crtc.c
> > index 177bbcb..3c37d8c 100644
> > --- a/drivers/gpu/drm/vkms/vkms_crtc.c
> > +++ b/drivers/gpu/drm/vkms/vkms_crtc.c
> > @@ -104,6 +104,7 @@ static void vkms_atomic_crtc_reset(struct drm_crtc 
> > *crtc)
> > vkms_state = kzalloc(sizeof(*vkms_state), GFP_KERNEL);
> > if (!vkms_state)
> > return;
> > +   INIT_WORK(_state->crc_work, vkms_crc_work_handle);
> 
> Presumably we should migrate/duplicate the crc_work state from the old state
> rather than just re-initializing? My context on the crc_work is foggy, but we
> should be sure that either:
> 
> a) the existing crc work is flushed and inactive, or
> b) we migrate the existing crc work to the duplicated state to keep track of 
> it

The various reset callbacks are used at driver load time to initialize
atomic kms state. Once we do have atomic states we're only using the
various duplicate_state callbacks, which already have the INIT_WORK here.
So was missing once at driver load, and we've hit it once on the first
frame. There is not existing/preceeding crc work when this code is called.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [PATCH] drm/vkms: Fix flush_work() without INIT_WORK().

2019-01-25 Thread Sean Paul 
On Sat, Jan 19, 2019 at 01:43:43AM +0900, Tetsuo Handa wrote:
> syzbot is hitting a lockdep warning [1] because flush_work() is called
> without INIT_WORK() after kzalloc() at vkms_atomic_crtc_reset().
> 
> Commit 6c234fe37c57627a ("drm/vkms: Implement CRC debugfs API") added
> INIT_WORK() to only vkms_atomic_crtc_duplicate_state() side. Assuming
> that lifecycle of crc_work is appropriately managed, fix this problem
> by adding INIT_WORK() to vkms_atomic_crtc_reset() side.
> 
> [1] 
> https://syzkaller.appspot.com/bug?id=a5954455fcfa51c29ca2ab55b203076337e1c770
> 
> Reported-and-tested-by: syzbot 
> 
> Signed-off-by: Tetsuo Handa 
> ---
>  drivers/gpu/drm/vkms/vkms_crtc.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c 
> b/drivers/gpu/drm/vkms/vkms_crtc.c
> index 177bbcb..3c37d8c 100644
> --- a/drivers/gpu/drm/vkms/vkms_crtc.c
> +++ b/drivers/gpu/drm/vkms/vkms_crtc.c
> @@ -104,6 +104,7 @@ static void vkms_atomic_crtc_reset(struct drm_crtc *crtc)
>   vkms_state = kzalloc(sizeof(*vkms_state), GFP_KERNEL);
>   if (!vkms_state)
>   return;
> + INIT_WORK(_state->crc_work, vkms_crc_work_handle);

Presumably we should migrate/duplicate the crc_work state from the old state
rather than just re-initializing? My context on the crc_work is foggy, but we
should be sure that either:

a) the existing crc work is flushed and inactive, or
b) we migrate the existing crc work to the duplicated state to keep track of it

Sean

>  
>   crtc->state = _state->base;
>   crtc->state->crtc = crtc;
> -- 
> 1.8.3.1
> 
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-- 
Sean Paul, Software Engineer, Google / Chromium OS
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Re: [PATCH] drm/vkms: Fix flush_work() without INIT_WORK().

2019-01-23 Thread Shayenne Moura 
> syzbot is hitting a lockdep warning [1] because flush_work() is called
> without INIT_WORK() after kzalloc() at vkms_atomic_crtc_reset().
>
> Commit 6c234fe37c57627a ("drm/vkms: Implement CRC debugfs API") added
> INIT_WORK() to only vkms_atomic_crtc_duplicate_state() side. Assuming
> that lifecycle of crc_work is appropriately managed, fix this problem
> by adding INIT_WORK() to vkms_atomic_crtc_reset() side.
>
> [1] 
> https://syzkaller.appspot.com/bug?id=a5954455fcfa51c29ca2ab55b203076337e1c770
>
> Reported-and-tested-by: syzbot 
> 
> Signed-off-by: Tetsuo Handa 
> ---
>  drivers/gpu/drm/vkms/vkms_crtc.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c 
> b/drivers/gpu/drm/vkms/vkms_crtc.c
> index 177bbcb..3c37d8c 100644
> --- a/drivers/gpu/drm/vkms/vkms_crtc.c
> +++ b/drivers/gpu/drm/vkms/vkms_crtc.c
> @@ -104,6 +104,7 @@ static void vkms_atomic_crtc_reset(struct drm_crtc *crtc)
> vkms_state = kzalloc(sizeof(*vkms_state), GFP_KERNEL);
> if (!vkms_state)
> return;
> +   INIT_WORK(_state->crc_work, vkms_crc_work_handle);
>
> crtc->state = _state->base;
> crtc->state->crtc = crtc;
> --
> 1.8.3.1
>

Thank you for your patch!

Reviewed-by: Shayenne Moura 
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[PATCH] drm/vkms: Fix flush_work() without INIT_WORK().

2019-01-20 Thread Tetsuo Handa 
syzbot is hitting a lockdep warning [1] because flush_work() is called
without INIT_WORK() after kzalloc() at vkms_atomic_crtc_reset().

Commit 6c234fe37c57627a ("drm/vkms: Implement CRC debugfs API") added
INIT_WORK() to only vkms_atomic_crtc_duplicate_state() side. Assuming
that lifecycle of crc_work is appropriately managed, fix this problem
by adding INIT_WORK() to vkms_atomic_crtc_reset() side.

[1] 
https://syzkaller.appspot.com/bug?id=a5954455fcfa51c29ca2ab55b203076337e1c770

Reported-and-tested-by: syzbot 

Signed-off-by: Tetsuo Handa 
---
 drivers/gpu/drm/vkms/vkms_crtc.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c
index 177bbcb..3c37d8c 100644
--- a/drivers/gpu/drm/vkms/vkms_crtc.c
+++ b/drivers/gpu/drm/vkms/vkms_crtc.c
@@ -104,6 +104,7 @@ static void vkms_atomic_crtc_reset(struct drm_crtc *crtc)
vkms_state = kzalloc(sizeof(*vkms_state), GFP_KERNEL);
if (!vkms_state)
return;
+   INIT_WORK(_state->crc_work, vkms_crc_work_handle);
 
crtc->state = _state->base;
crtc->state->crtc = crtc;
-- 
1.8.3.1

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