linux-kernel - Re: [PATCH v11 05/10] test_firmware: add support for firmware_request

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Message-ID: <20200113145328.GA11244@42.do-not-panic.com>
Date:   Mon, 13 Jan 2020 14:53:28 +0000
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     Hans de Goede <hdegoede@...hat.com>
Cc:     Ard Biesheuvel <ardb@...nel.org>,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        Jonathan Corbet <corbet@....net>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Peter Jones <pjones@...hat.com>,
        Dave Olsthoorn <dave@...aar.me>, x86@...nel.org,
        platform-driver-x86@...r.kernel.org, linux-efi@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-input@...r.kernel.org
Subject: Re: [PATCH v11 05/10] test_firmware: add support for
 firmware_request_platform

On Sat, Jan 11, 2020 at 03:56:58PM +0100, Hans de Goede wrote:
> Add support for testing firmware_request_platform through a new
> trigger_request_platform trigger.
> 
> Signed-off-by: Hans de Goede <hdegoede@...hat.com>
> ---
> Changes in v11:
> - Drop a few empty lines which were accidentally introduced

But you didn't address my other feedback.

> --- a/lib/test_firmware.c
> +++ b/lib/test_firmware.c
> @@ -507,6 +508,61 @@ static ssize_t trigger_request_store(struct device *dev,
>  }
>  static DEVICE_ATTR_WO(trigger_request);
>  
> +#ifdef CONFIG_EFI_EMBEDDED_FIRMWARE
> +static ssize_t trigger_request_platform_store(struct device *dev,
> +					      struct device_attribute *attr,
> +					      const char *buf, size_t count)
> +{
> +	static const u8 test_data[] = {
> +		0x55, 0xaa, 0x55, 0xaa, 0x01, 0x02, 0x03, 0x04,
> +		0x55, 0xaa, 0x55, 0xaa, 0x05, 0x06, 0x07, 0x08,
> +		0x55, 0xaa, 0x55, 0xaa, 0x10, 0x20, 0x30, 0x40,
> +		0x55, 0xaa, 0x55, 0xaa, 0x50, 0x60, 0x70, 0x80
> +	};
> +	struct efi_embedded_fw fw;
> +	int rc;
> +	char *name;
> +
> +	name = kstrndup(buf, count, GFP_KERNEL);
> +	if (!name)
> +		return -ENOSPC;
> +
> +	pr_info("inserting test platform fw '%s'\n", name);
> +	fw.name = name;
> +	fw.data = (void *)test_data;
> +	fw.length = sizeof(test_data);
> +	list_add(&fw.list, &efi_embedded_fw_list);
> +
> +	pr_info("loading '%s'\n", name);
> +

I mentioned this in my last review, and it seems you forgot to address
this. But now some more feedback:

These two:

> +	mutex_lock(&test_fw_mutex);
> +	release_firmware(test_firmware);

You are doing this because this is a test, but a typical driver will
do this after, and we don't loose anything in doing this after. Can you
move the mutex lock and assign the pointer to a temporary used pointer
for the call, *after* your call.

But since your test is not using any interfaces to query information
about the firmware, and you are just doing the test in C code right
away, instead of say, using a trigger for later use in userspace,
you can just do away with the mutex lock and make the call use its
own pointer:

	rc = firmware_request_platform(&tmp_test_firmware, name, dev);
	if (rc) {
		...
	}
	/* Your test branch code goes here */

I see no reason why you use the test_firmware pointer.

> +	test_firmware = NULL;
> +	rc = firmware_request_platform(&test_firmware, name, dev);
> +	if (rc) {
> +		pr_info("load of '%s' failed: %d\n", name, rc);
> +		goto out;
> +	}
> +	if (test_firmware->size != sizeof(test_data) ||
> +	    memcmp(test_firmware->data, test_data, sizeof(test_data)) != 0) {
> +		pr_info("firmware contents mismatch for '%s'\n", name);
> +		rc = -EINVAL;
> +		goto out;
> +	}
> +	pr_info("loaded: %zu\n", test_firmware->size);
> +	rc = count;
> +
> +out:
> +	mutex_unlock(&test_fw_mutex);
> +
> +	list_del(&fw.list);
> +	kfree(name);
> +
> +	return rc;
> +}