linux-kernel - Re: [PATCH] soc: ti: wkup_m3_ipc: Fix race condition with rproc

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Message-ID: <20191217182534.GD35479@atomide.com>
Date:   Tue, 17 Dec 2019 10:25:34 -0800
From:   Tony Lindgren <tony@...mide.com>
To:     Dave Gerlach <d-gerlach@...com>
Cc:     Santosh Shilimkar <ssantosh@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-omap@...r.kernel.org, Suman Anna <s-anna@...com>
Subject: Re: [PATCH] soc: ti: wkup_m3_ipc: Fix race condition with rproc_boot

Hi,

* Dave Gerlach <d-gerlach@...com> [191211 20:02]:
> Any user of wkup_m3_ipc calls wkup_m3_ipc_get to get a handle and this
> checks the value of the static variable m3_ipc_state to see if the
> wkup_m3 is ready. Currently this is populated during probe before
> rproc_boot has been called, meaning there is a window of time that
> wkup_m3_ipc_get can return a valid handle but the wkup_m3 itself is not
> ready, leading to invalid IPC calls to the wkup_m3 and system
> instability.
> 
> To avoid this, move the population of the m3_ipc_state variable until
> after rproc_boot has succeeded to guarantee a valid and usable handle
> is always returned.

Santosh, do you want me to pick this one into my fixes branch?

Regards,

Tony


> Reported-by: Suman Anna <s-anna@...com>
> Signed-off-by: Dave Gerlach <d-gerlach@...com>
> ---
>  drivers/soc/ti/wkup_m3_ipc.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/soc/ti/wkup_m3_ipc.c b/drivers/soc/ti/wkup_m3_ipc.c
> index 378369d9364a..e9ece45d7a33 100644
> --- a/drivers/soc/ti/wkup_m3_ipc.c
> +++ b/drivers/soc/ti/wkup_m3_ipc.c
> @@ -419,6 +419,8 @@ static void wkup_m3_rproc_boot_thread(struct wkup_m3_ipc *m3_ipc)
>  	ret = rproc_boot(m3_ipc->rproc);
>  	if (ret)
>  		dev_err(dev, "rproc_boot failed\n");
> +	else
> +		m3_ipc_state = m3_ipc;
>  
>  	do_exit(0);
>  }
> @@ -505,8 +507,6 @@ static int wkup_m3_ipc_probe(struct platform_device *pdev)
>  		goto err_put_rproc;
>  	}
>  
> -	m3_ipc_state = m3_ipc;
> -
>  	return 0;
>  
>  err_put_rproc:
> -- 
> 2.20.1
>