From: Andrew Morton <akpm@osdl.org>
To: Oliver Xymoron <oxymoron@waste.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH] [1/2] random: SMP locking
Date: Sat, 2 Aug 2003 04:00:15 -0700 [thread overview]
Message-ID: <20030802040015.0fcafda2.akpm@osdl.org> (raw)
In-Reply-To: <20030802042445.GD22824@waste.org>
Oliver Xymoron <oxymoron@waste.org> wrote:
>
> This patch adds locking for SMP. Apparently Willy never managed to
> revive his laptop with his version so I revived mine.
hrm. I'm a random ignoramus. I'll look it over...
Are you really sure that all the decisions about where to use spin_lock()
vs spin_lock_irq() vs spin_lock_irqsave() are correct? They are
non-obvious.
> @@ -1619,18 +1660,23 @@
> if (!capable(CAP_SYS_ADMIN))
> return -EPERM;
> p = (int *) arg;
> + spin_lock(&random_state->lock);
> ent_count = random_state->entropy_count;
> if (put_user(ent_count, p++) ||
> get_user(size, p) ||
> put_user(random_state->poolinfo.poolwords, p++))
Cannot perform userspace access while holding a lock - a pagefault could
occur, perform IO, schedule away and the same CPU tries to take the same
lock via a different process.
next prev parent reply other threads:[~2003-08-02 10:59 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-08-02 4:24 [PATCH] [1/2] random: SMP locking Oliver Xymoron
2003-08-02 11:00 ` Andrew Morton [this message]
2003-08-02 12:35 ` Zwane Mwaikambo
2003-08-02 14:43 ` Matt Mackall
2003-08-02 15:02 ` Zwane Mwaikambo
2003-08-02 18:39 ` Andrew Morton
2003-08-02 18:42 ` Matt Mackall
2003-08-02 14:32 ` Matt Mackall
2003-08-02 19:00 ` Andrew Morton
2003-08-02 19:33 ` Matt Mackall
2003-08-02 19:46 ` Andrew Morton
2003-08-02 20:14 ` Matt Mackall
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