linux-kernel - Re: [PATCH net-next 9/9] net: ipa: use a bitmap for enabled endpoints

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Message-ID: <20221101213404.3e4c3b8f@kernel.org>
Date:   Tue, 1 Nov 2022 21:34:04 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Alex Elder <elder@...aro.org>
Cc:     davem@...emloft.net, edumazet@...gle.com, pabeni@...hat.com,
        mka@...omium.org, evgreen@...omium.org, andersson@...nel.org,
        quic_cpratapa@...cinc.com, quic_avuyyuru@...cinc.com,
        quic_jponduru@...cinc.com, quic_subashab@...cinc.com,
        elder@...nel.org, netdev@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 9/9] net: ipa: use a bitmap for enabled
 endpoints

On Sat, 29 Oct 2022 19:18:28 -0500 Alex Elder wrote:
>  	/* Set up the defined endpoint bitmap */
>  	ipa->defined = bitmap_zalloc(ipa->endpoint_count, GFP_KERNEL);
>  	ipa->set_up = bitmap_zalloc(ipa->endpoint_count, GFP_KERNEL);
> +	ipa->enabled = bitmap_zalloc(ipa->endpoint_count, GFP_KERNEL);
>  	if (!ipa->defined || !ipa->set_up) {

This condition should now check if ipa->enabled

And the error handling patch needs to free it, in case it was something
else that didn't get allocated?

Frankly I have gotten mass-NULL-checks wrong more than once myself so
I'd steer clear of those, they are strangely error prone.

>  		dev_err(dev, "unable to allocate endpoint bitmaps\n");

this error message should not be here (patch 5 adds it I think)
memory allocation failures produce a splat, no need to print errors

> +		bitmap_free(ipa->set_up);
> +		ipa->set_up = NULL;
>  		bitmap_free(ipa->defined);