From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tony Lindgren <tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>
Subject: Re: [PATCH] dmaengine: cppi41: Fix oops in cppi41_runtime_resume
Date: Thu, 12 Jan 2017 16:03:15 -0800
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To: Grygorii Strashko <grygorii.strashko-l0cyMroinI0@public.gmane.org>
Cc: Dan Williams <dan.j.williams-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Vinod Koul <vinod.koul-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Bin Liu <b-liu-l0cyMroinI0@public.gmane.org>, Daniel Mack <zonque-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Felipe Balbi <felipe.balbi-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>, George Cherian <george.cherian-l0cyMroinI0@public.gmane.org>, Johan Hovold <johan-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Peter Ujfalusi <peter.ujfalusi-l0cyMroinI0@public.gmane.org>, Sekhar Nori <nsekhar-l0cyMroinI0@public.gmane.org>, Sebastian Andrzej Siewior <bigeasy-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>, dmaengine-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Andy Shevchenko <andy.shevchenko-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Kevin Hilman <khilman-rdvid1DuHRBWk0Htik3J/w@public.gmane.org>, Patrick Titiano <ptitiano-rdvid1DuHRBWk0Htik3J/w@public.gmane.org>, Sergei Shtylyov <sergei.shtylyov-M4DtvfQ/ZS1MRgGoP+s0PdBPR1lH4CV8@public.gmane.org>
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* Grygorii Strashko <grygorii.strashko-l0cyMroinI0@public.gmane.org> [170112 15:43]:
> @@ -457,38 +449,36 @@ static void push_desc_queue(struct cppi41_channel *c)
>         cppi_writel(reg, cdd->qmgr_mem + QMGR_QUEUE_D(c->q_num));
>  }
>  
> -static void pending_desc(struct cppi41_channel *c)
> +static void cppi41_dma_issue_pending(struct dma_chan *chan)
>  {
> +       struct cppi41_channel *c = to_cpp41_chan(chan);
>         struct cppi41_dd *cdd = c->cdd;
> +       int error;
> +       struct cppi41_channel *_c;
>         unsigned long flags;
>  
>         spin_lock_irqsave(&cdd->lock, flags);
>         list_add_tail(&c->node, &cdd->pending);
> -       spin_unlock_irqrestore(&cdd->lock, flags);
> -}
> -
> -static void cppi41_dma_issue_pending(struct dma_chan *chan)
> -{
> -       struct cppi41_channel *c = to_cpp41_chan(chan);
> -       struct cppi41_dd *cdd = c->cdd;
> -       int error;
>  
>         error = pm_runtime_get(cdd->ddev.dev);
> -       if ((error != -EINPROGRESS) && error < 0) {
> +       if (error < 0) {
>                 pm_runtime_put_noidle(cdd->ddev.dev);
>                 dev_err(cdd->ddev.dev, "Failed to pm_runtime_get: %i\n",
>                         error);
> -
> +               spin_unlock_irqrestore(&cdd->lock, flags);
>                 return;
>         }
>  
> -       if (likely(pm_runtime_active(cdd->ddev.dev)))
> -               push_desc_queue(c);
> -       else
> -               pending_desc(c);
> +       if (!cdd->is_suspended) {
> +               list_for_each_entry_safe(c, _c, &cdd->pending, node) {
> +                       push_desc_queue(c);
> +                       list_del(&c->node);
> +               };
> +       }
>  
>         pm_runtime_mark_last_busy(cdd->ddev.dev);
>         pm_runtime_put_autosuspend(cdd->ddev.dev);
> +       spin_lock_irqsave(&cdd->lock, flags);
>  }

So always add to the queue no matter, then always flush the queue
directly if active? Yeah that might work :)

Don't we need spinlock in the list_for_each_entry_safe() to prevent
it racing with runtime_resume() though?

Tony
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