linux-kernel - Re: [PATCHv3 1/5] efi/runtime-wrappers: detect FW irq flag corruption

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Date:	Mon, 25 Apr 2016 16:18:41 +0200
From:	Ard Biesheuvel <ard.biesheuvel@...aro.org>
To:	Matt Fleming <matt@...eblueprint.co.uk>
Cc:	Robin Murphy <robin.murphy@....com>,
	Mark Rutland <mark.rutland@....com>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Leif Lindholm <leif.lindholm@...aro.org>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"hpa@...or.com" <hpa@...or.com>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCHv3 1/5] efi/runtime-wrappers: detect FW irq flag corruption

On 25 April 2016 at 16:15, Matt Fleming <matt@...eblueprint.co.uk> wrote:
> On Mon, 25 Apr, at 03:12:01PM, Robin Murphy wrote:
>> >+static void efi_call_virt_check_flags(unsigned long flags, const char *call)
>> >+{
>> >+    unsigned long cur_flags;
>> >+    bool mismatch;
>> >+
>> >+    local_save_flags(cur_flags);
>> >+
>> >+    mismatch = !!((cur_flags ^ flags) & ARCH_EFI_IRQ_FLAGS_MASK);
>>
>> nit: the assignment itself is already a conversion to bool, so the
>> excitement is redundant here.
>
> This was intentional. I asked Mark to make this change so that it's
> explicit for the developer that we're performing the type conversion.

But replacing an implicit boolean cast with an explicit one makes
little sense, no? Don't we simply want '!= 0' here if you need a
boolean expression?