linux-kernel - Re: [PATCH] kexec jump: fix compiling warning on xchg(&kexec_lock, 0) in kernel

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: <alpine.LFD.1.10.0808130958220.3462@nehalem.linux-foundation.org>
Date:	Wed, 13 Aug 2008 10:01:13 -0700 (PDT)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
cc:	Huang Ying <ying.huang@...el.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Pavel Machek <pavel@....cz>, nigel@...el.suspend2.net,
	"Rafael J. Wysocki" <rjw@...k.pl>, Vivek Goyal <vgoyal@...hat.com>,
	mingo@...e.hu, linux-kernel@...r.kernel.org,
	Kexec Mailing List <kexec@...ts.infradead.org>
Subject: Re: [PATCH] kexec jump: fix compiling warning on xchg(&kexec_lock,
 0) in kernel_kexec()



On Wed, 13 Aug 2008, Andrew Morton wrote:
>
> We don't need to create that local.  I queued this:

No, please don't. 

Just don't take this whole patch-series until it's cleaned up. There is 
absolutely no excuse for using xchg as a locking primitive. Nothing like 
this should be queued anywhere, it should be burned and the ashes should 
be scattered over the atlantic so that nobody will ever see them again.

F*ck me with a spoon, if you have to use xchg() to do a trylock, why the 
hell isn't the unlock sequence then

	smp_mb();
	var = 0;

instead? Not that that's really right either, but at least it avoids the 
_ridiculous_ crap. The real solution is probably to use a spinlock and 
trylock/unlock.

		Linus
--
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/