linux-kernel - Re: [PATCH 2/2] media: venus: sync with threaded IRQ during inst destruction

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Message-ID: <20241024051335.GK1279924@google.com>
Date: Thu, 24 Oct 2024 14:13:35 +0900
From: Sergey Senozhatsky <senozhatsky@...omium.org>
To: Sergey Senozhatsky <senozhatsky@...omium.org>
Cc: Stanimir Varbanov <stanimir.k.varbanov@...il.com>,
	Vikash Garodia <quic_vgarodia@...cinc.com>,
	Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] media: venus: sync with threaded IRQ during inst
 destruction

On (24/10/24 13:58), Sergey Senozhatsky wrote:
> Date: Thu, 24 Oct 2024 13:58:36 +0900
> From: Sergey Senozhatsky <senozhatsky@...omium.org>
> To: Sergey Senozhatsky <senozhatsky@...omium.org>
> Cc: Stanimir Varbanov <stanimir.k.varbanov@...il.com>, Vikash Garodia
>  <quic_vgarodia@...cinc.com>, Bryan O'Donoghue
>  <bryan.odonoghue@...aro.org>, linux-media@...r.kernel.org,
>  linux-kernel@...r.kernel.org
> Subject: Re: [PATCH 2/2] media: venus: sync with threaded IRQ during inst
>  destruction
> Message-ID: <20241024045836.GJ1279924@...gle.com>
> 
> On (24/10/23 14:24), Sergey Senozhatsky wrote:
> > Guard inst destruction (both dec and enc) with hard and threaded
> > IRQ synchronization.
> 
> Folks, please ignore this patch.   Stand by for v2.

I think it probably should be something like this (both for dec and
enc).

---

@@ -1538,9 +1538,25 @@ static int venc_close(struct file *file)
 
        venc_pm_get(inst);
 
+       /*
+        * First, remove the inst from the ->instances list, so that
+        * to_instance() will return NULL.
+        */
+       hfi_session_destroy(inst);
+       /*
+        * Second, make sure we don't have IRQ/IRQ-thread currently running or
+        * pending execution (disable_irq() calls synchronize_irq()), which
+        * can race with the inst destruction.
+        */
+       disable_irq(inst->core->irq);
+       /*
+        * Lastly, inst is gone from the core->instances list and we don't
+        * have running/pending IRQ/IRQ-thread, proceed with the destruction
+        */
+       enable_irq(inst->core->irq);
+
        v4l2_m2m_ctx_release(inst->m2m_ctx);
        v4l2_m2m_release(inst->m2m_dev);
-       hfi_session_destroy(inst);
        v4l2_fh_del(&inst->fh);
        v4l2_fh_exit(&inst->fh);
        venc_ctrl_deinit(inst);