linux-kernel - Re: [PATCH] firmware: Do not use WARN_ON(!spin_is

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20140813141836.GQ15082@console-pimps.org>
Date:	Wed, 13 Aug 2014 15:18:36 +0100
From:	Matt Fleming <matt@...sole-pimps.org>
To:	Guenter Roeck <linux@...ck-us.net>
Cc:	Matt Fleming <matt.fleming@...el.com>, linux-efi@...r.kernel.org,
	linux-kernel@...r.kernel.org, Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH] firmware: Do not use WARN_ON(!spin_is_locked())

On Sun, 10 Aug, at 08:54:13PM, Guenter Roeck wrote:
> spin_is_locked() always returns false for uniprocessor configurations,
> so do not use WARN_ON with it. WARN_ON_SMP() exists for that very
> purpose and must be used instead.
 
Good catch, though I worry that WARN_ON_SMP() doesn't seem to be a very
common pattern,

arch/x86/pci/i386.c:	WARN_ON_SMP(!spin_is_locked(&pcibios_fwaddrmap_lock));
drivers/gpu/drm/drm_irq.c:	WARN_ON_SMP(!spin_is_locked(&dev->event_lock));
include/asm-generic/bug.h: * WARN_ON_SMP() is for cases that the warning is either
include/asm-generic/bug.h: *	WARN_ON_SMP(!zoot->bar);
include/asm-generic/bug.h: * For CONFIG_SMP, WARN_ON_SMP() should act the same as WARN_ON(),
include/asm-generic/bug.h: * if (WARN_ON_SMP(x)) returns true only when CONFIG_SMP is set
include/asm-generic/bug.h:# define WARN_ON_SMP(x)			WARN_ON(x)
include/asm-generic/bug.h: * Use of ({0;}) because WARN_ON_SMP(x) may be used either as
include/asm-generic/bug.h:# define WARN_ON_SMP(x)			({0;})
kernel/futex.c:	if (WARN_ON_SMP(!q->lock_ptr || !spin_is_locked(q->lock_ptr))

and people must want to do this kind of checking all the time.

How about lockdep_assert_held()? That seems to be much more popular.

-- 
Matt Fleming, Intel Open Source Technology Center
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/