linux-kernel - Re: [PATCH 2/4] rtc: abx80x: Enable SQW output

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Date:   Tue, 30 Mar 2021 18:28:32 +0300
From:   Kirill Kapranov <kirill.kapranov@...pulab.co.il>
To:     Dan Carpenter <dan.carpenter@...cle.com>, kbuild@...ts.01.org,
        a.zummo@...ertech.it, alexandre.belloni@...tlin.com,
        phdm@...qel.be, linux-rtc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     lkp@...el.com, kbuild-all@...ts.01.org
Subject: Re: [PATCH 2/4] rtc: abx80x: Enable SQW output

Hi Dan,

Thank you very much for pointing out the issues.
However, I'm not sure that the code, you have analyzed, will be a part 
of final patch set. I intend to redesign all the code deeply, as 
Alexandre Belloni suggested [1].

Thank you again!

-- 
Best Regards,
Kirill Kapranov
Software Engineer
CompuLab Ltd.
[1] https://marc.info/?l=linux-rtc&m=161696606727215&w=2

On 3/29/21 9:19 AM, Dan Carpenter wrote:
> Hi Kirill,
> 
> url:    https://github.com/0day-ci/linux/commits/Kirill-Kapranov/rtc-abx80x-Enable-distributed-digital-calibration/20210329-053233
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/abelloni/linux.git rtc-next
> config: i386-randconfig-m021-20210328 (attached as .config)
> compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
> 
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@...el.com>
> Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
> 
> smatch warnings:
> drivers/rtc/rtc-abx80x.c:561 sqw_set() error: uninitialized symbol 'retval'.
> 
> vim +/retval +561 drivers/rtc/rtc-abx80x.c
> 
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  527  static int sqw_set(struct i2c_client *client, const char *buf)
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  528  {
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  529  	union abx8xx_reg_sqw reg_sqw;
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  530  	int retval;
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  531
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  532  	reg_sqw.val = i2c_smbus_read_byte_data(client, ABX8XX_REG_SQW);
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  533  	if (reg_sqw.val < 0)
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  534  		goto err;
> 
> "retval" not set.  Forgetting to set the error code is the canonical
> bug for do nothing gotos like this.
> 
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  535
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  536  	if (sysfs_streq(buf, "none")) {
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  537  		reg_sqw.sqwe = 0;
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  538  		dev_info(&client->dev, "sqw output disabled\n");
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  539  	} else {
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  540  		int idx = __sysfs_match_string(sqfs, SQFS_COUNT, buf);
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  541
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  542  		if (idx < 0)
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  543  			return idx;
>                                                                          ^^^^^^^^^^^
> These are direct returns.  Just do direct returns everywhere (more
> readably, fewer bugs).
> 
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  544
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  545  		if (abx80x_is_rc_mode(client) && !valid_for_rc_mode[idx])
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  546  			dev_warn(&client->dev, "sqw frequency %s valid only in xt mode\n",
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  547  				sqfs[idx]);
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  548
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  549  		dev_info(&client->dev, "sqw output enabled @ %s\n", sqfs[idx]);
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  550  		reg_sqw.sqwe = 1;
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  551  		reg_sqw.sqws = idx;
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  552  	}
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  553
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  554  	retval = i2c_smbus_write_byte_data(client, ABX8XX_REG_SQW, reg_sqw.val);
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  555  	if (retval < 0)
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  556  		goto err;
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  557
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  558  	return 0;
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  559  err:
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  560  	dev_err(&client->dev, "Failed to set SQW\n");
> 3f6d456de4f347 Kirill Kapranov 2021-03-29 @561  	return retval;
>                                                          ^^^^^^^^^^^^^
> 
> 3f6d456de4f347 Kirill Kapranov 2021-03-29  562
> 
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
>