linux-kernel - Re: [PATCH] Proposed removal of IS_ERR_OR_NULL() (was: Re: [PATCH 1/4] gpiolib: introduce descriptor-based GPIO interface)

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Message-ID: <20130109155154.GN3931@n2100.arm.linux.org.uk>
Date:	Wed, 9 Jan 2013 15:51:54 +0000
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Nicolas Pitre <nicolas.pitre@...aro.org>
Cc:	Arnd Bergmann <arnd@...db.de>, linux-arch@...r.kernel.org,
	Linus Walleij <linus.walleij@...aro.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Grant Likely <grant.likely@...retlab.ca>,
	Alexandre Courbot <acourbot@...dia.com>,
	Guenter Roeck <linux@...ck-us.net>,
	"devicetree-discuss@...ts.ozlabs.org" 
	<devicetree-discuss@...ts.ozlabs.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] Proposed removal of IS_ERR_OR_NULL() (was: Re: [PATCH
	1/4] gpiolib: introduce descriptor-based GPIO interface)

On Wed, Jan 09, 2013 at 10:27:53AM -0500, Nicolas Pitre wrote:
> Anyone with good coccinelle skills around to deal with the users?

I'm not sure that's a solution.

For example:

        err = gpio_request(en_vdd_1v05, "EN_VDD_1V05");
        if (err) {
                pr_err("%s: gpio_request failed: %d\n", __func__, err);   
                return err;   
        }
...
        regulator = regulator_get(NULL, "vdd_ldo0,vddio_pex_clk");
        if (IS_ERR_OR_NULL(regulator)) {
                pr_err("%s: regulator_get failed: %d\n", __func__,
                       (int)PTR_ERR(regulator));
                goto err_reg;
        }

        regulator_enable(regulator);

        err = tegra_pcie_init(true, true);
...
err_reg:
        gpio_free(en_vdd_1v05);
                
        return err;
}

Now, regulator_get() returns error-pointers for real errors when it's
configured in.  When regulator support is not configured, it returns
NULL.

So, one solution here would be:

	if (IS_ERR(regulator)) {
		err = PTR_ERR(regulator);
		pr_err("%s: regulator_get failed: %d\n", __func__, err);
		goto err_reg;
	}

but leaves us with the question: is it safe to call tegra_pcie_init()
without regulator support?

The problem there is that "fixing" this causes a behavioural change in
the code, and we don't know what effect that change may have.
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