linux-kernel - Re: [PATCH net 1/2] net: ipa: only clear hardware state if setup has completed

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Date:   Fri, 9 Oct 2020 12:25:17 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Alex Elder <elder@...aro.org>
Cc:     davem@...emloft.net, evgreen@...omium.org, subashab@...eaurora.org,
        cpratapa@...eaurora.org, bjorn.andersson@...aro.org,
        mka@...omium.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net 1/2] net: ipa: only clear hardware state if setup
 has completed

On Tue,  6 Oct 2020 16:30:46 -0500 Alex Elder wrote:
> In the setup phase of initialization, GSI firmware gets loaded
> and initialized, and the AP command TX and default RX endpoints
> get set up.  Until that happens, IPA commands must not be issued
> to the hardware.
> 
> If the modem crashes, we stop endpoint channels and perform a
> number of other activities to clear modem-related IPA state,
> including zeroing filter and routing tables (using IPA commands).
> This is a bug if setup is not complete.  We should also not be
> performing the other cleanup activity in that case either.
> 
> Fix this by returning immediately when handling a modem crash if we
> haven't completed setup.
> 
> Fixes: a646d6ec9098 ("soc: qcom: ipa: modem and microcontroller")
> Tested-by: Matthias Kaehlcke <mka@...omium.org>
> Signed-off-by: Alex Elder <elder@...aro.org>

> diff --git a/drivers/net/ipa/ipa_modem.c b/drivers/net/ipa/ipa_modem.c
> index e34fe2d77324e..dd5b89c5cb2d4 100644
> --- a/drivers/net/ipa/ipa_modem.c
> +++ b/drivers/net/ipa/ipa_modem.c
> @@ -285,6 +285,9 @@ static void ipa_modem_crashed(struct ipa *ipa)
>  	struct device *dev = &ipa->pdev->dev;
>  	int ret;
>  
> +	if (!ipa->setup_complete)
> +		return;
> +
>  	ipa_endpoint_modem_pause_all(ipa, true);
>  
>  	ipa_endpoint_modem_hol_block_clear_all(ipa);

The only call site already checks setup_complete, so this is not needed,
no?

$ git grep -C2 ipa_modem_crashed\(
drivers/net/ipa/ipa_modem.c-
drivers/net/ipa/ipa_modem.c-/* Treat a "clean" modem stop the same as a crash */
drivers/net/ipa/ipa_modem.c:static void ipa_modem_crashed(struct ipa *ipa)
drivers/net/ipa/ipa_modem.c-{
drivers/net/ipa/ipa_modem.c-    struct device *dev = &ipa->pdev->dev;
--
drivers/net/ipa/ipa_modem.c-                     notify_data->crashed ? "crashed" : "stopping");
drivers/net/ipa/ipa_modem.c-            if (ipa->setup_complete)
drivers/net/ipa/ipa_modem.c:                    ipa_modem_crashed(ipa);
drivers/net/ipa/ipa_modem.c-            break;
drivers/net/ipa/ipa_modem.c-