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

[Alex Elder]

On 10/9/20 2:25 PM, Jakub Kicinski wrote:
> 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@xxxxxxxxxxxx>
> > Signed-off-by: Alex Elder <elder@xxxxxxxxxx>
>
> > 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?

Wow, you are correct.

I was mainly focused on the fact that the ipa_modem_crashed()
call could happen asynchronously, and that it called
ipa_table_reset() which requires IPA immediate commands.
I should have followed it back to its callers.

I agree with you, this is not needed.  The other patch
is definitely needed though.

Would you like me to re-post that single patch, or is
it acceptable as-is?

Thank you for reviewing this and catching my mistake.

					-Alex

> $ 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-