linux-kernel - Re: [PATCH] firmware: stratix10-rsu: prevent io block when sending RSU messages

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Date:   Mon, 10 Jul 2023 18:15:54 -0500
From:   Dinh Nguyen <dinguyen@...nel.org>
To:     kah.jing.lee@...el.com
Cc:     linux-kernel@...r.kernel.org, tien.sung.ang@...el.com
Subject: Re: [PATCH] firmware: stratix10-rsu: prevent io block when sending
 RSU messages



On 7/4/23 21:18, kah.jing.lee@...el.com wrote:
> From: Kah Jing Lee <kah.jing.lee@...el.com>
> 
> Fix the issue for preventing recursive rsu mutex lock
> issue in RSU update command.

This message is a bit confusing. What "issue" is preventing a lock issue?

> 
> Signed-off-by: Kah Jing Lee <kah.jing.lee@...el.com>
> ---
>   drivers/firmware/stratix10-rsu.c | 8 ++++++--
>   1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/firmware/stratix10-rsu.c b/drivers/firmware/stratix10-rsu.c
> index e51c95f8d445..0a7542e9bb6f 100644
> --- a/drivers/firmware/stratix10-rsu.c
> +++ b/drivers/firmware/stratix10-rsu.c
> @@ -280,7 +280,9 @@ static int rsu_send_msg(struct stratix10_rsu_priv *priv,
>   	struct stratix10_svc_client_msg msg;
>   	int ret;
>   
> -	mutex_lock(&priv->lock);
> +	if (!mutex_trylock(&priv->lock))
> +		return -EAGAIN;
> +
>   	reinit_completion(&priv->completion);
>   	priv->client.receive_cb = callback;
>   
> @@ -525,7 +527,9 @@ static ssize_t reboot_image_store(struct device *dev,
>   
>   	ret = rsu_send_msg(priv, COMMAND_RSU_UPDATE,
>   			   address, rsu_command_callback);
> -	if (ret) {
> +	if (ret == -EAGAIN)
> +		return 0;
> +	else if (ret) {
>   		dev_err(dev, "Error, RSU update returned %i\n", ret);
>   		return ret;
>   	}