linux-kernel - Re: spinlock_irqsave() && flags (Was: pm80xx: Spinlock fix)

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]

Date:	Mon, 23 Dec 2013 10:12:57 -0800
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Jason Seba <jason.seba42@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Tomas Henzl <thenzl@...hat.com>, Jack Wang <xjtuwjp@...il.com>,
	Suresh Thiagarajan <Suresh.Thiagarajan@...s.com>,
	Viswas G <Viswas.G@...s.com>,
	"linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
	"JBottomley@...allels.com" <JBottomley@...allels.com>,
	Vasanthalakshmi Tharmarajan 
	<Vasanthalakshmi.Tharmarajan@...s.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: spinlock_irqsave() && flags (Was: pm80xx: Spinlock fix)

On Mon, Dec 23, 2013 at 9:27 AM, Oleg Nesterov <oleg@...hat.com> wrote:
>
> In short, is this code
>
>         spinlock_t LOCK;
>         unsigned long FLAGS;
>
>         void my_lock(void)
>         {
>                 spin_lock_irqsave(&LOCK, FLAGS);
>         }
>
>         void my_unlock(void)
>         {
>                 spin_unlock_irqrestore(&LOCK, FLAGS);
>         }
>
> correct or not?

Hell no. "flags" needs to be a thread-private variable, or at least
protected some way (ie the above could work if everything is inside a
bigger lock, to serialize access to FLAGS).

                    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/