netdev - Re: [PATCH v7 2/2] KEYS: Avoid false positive ENOMEM error on key read

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Date:   Sun, 22 Mar 2020 09:31:21 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:     Waiman Long <longman@...hat.com>
Cc:     David Howells <dhowells@...hat.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        Mimi Zohar <zohar@...ux.ibm.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, keyrings@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        linux-integrity@...r.kernel.org, netdev@...r.kernel.org,
        linux-afs@...ts.infradead.org, Sumit Garg <sumit.garg@...aro.org>,
        Jerry Snitselaar <jsnitsel@...hat.com>,
        Roberto Sassu <roberto.sassu@...wei.com>,
        Eric Biggers <ebiggers@...gle.com>,
        Chris von Recklinghausen <crecklin@...hat.com>
Subject: Re: [PATCH v7 2/2] KEYS: Avoid false positive ENOMEM error on key
 read

On 2020/03/22 3:49, Waiman Long wrote:
> +	do {

> +		if (ret > key_data_len) {
> +			if (unlikely(key_data))
> +				__kvzfree(key_data, key_data_len);
> +			key_data_len = ret;
> +			continue;	/* Allocate buffer */

Excuse me, but "continue;" inside "do { ... } while (0);" means "break;"
because "while (0)" is evaluated before continuing the loop.

----------
#include <stdio.h>

int main(int argc, char *argv[])
{
        do {
                printf("step 1\n");
                if (1) {
                        printf("step 2\n");
                        continue;
                }
                printf("step 3\n");
        } while (0);
        printf("step 4\n");
        return 0;
}
----------

----------
step 1
step 2
step 4
----------

> +		}

> +	} while (0);