From: Andrew Morton <akpm@linux-foundation.org>
To: Cong Wang <xiyou.wangcong@gmail.com>
Cc: linux-kernel@vger.kernel.org, Prarit Bhargava <prarit@redhat.com>,
Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <greg@kroah.com>
Subject: Re: [Patch] lkdtm: avoid calling lkdtm_do_action() with spin lock held
Date: Mon, 30 Jan 2012 12:54:29 -0800 [thread overview]
Message-ID: <20120130125429.56f6f7d0.akpm@linux-foundation.org> (raw)
In-Reply-To: <1327755168-12240-1-git-send-email-xiyou.wangcong@gmail.com>
On Sat, 28 Jan 2012 20:52:47 +0800
Cong Wang <xiyou.wangcong@gmail.com> wrote:
> lkdtm_do_action() may call sleeping functions like kmalloc(),
> so do not call it with spin lock held.
>
> Cc: Prarit Bhargava <prarit@redhat.com>
> Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com>
>
> ---
> diff --git a/drivers/misc/lkdtm.c b/drivers/misc/lkdtm.c
> index 150cd70..28adefe 100644
> --- a/drivers/misc/lkdtm.c
> +++ b/drivers/misc/lkdtm.c
> @@ -354,6 +354,7 @@ static void lkdtm_do_action(enum ctype which)
> static void lkdtm_handler(void)
> {
> unsigned long flags;
> + bool do_it = false;
>
> spin_lock_irqsave(&count_lock, flags);
> count--;
> @@ -361,10 +362,13 @@ static void lkdtm_handler(void)
> cp_name_to_str(cpoint), cp_type_to_str(cptype), count);
>
> if (count == 0) {
> - lkdtm_do_action(cptype);
> + do_it = true;
> count = cpoint_count;
> }
> spin_unlock_irqrestore(&count_lock, flags);
> +
> + if (do_it)
> + lkdtm_do_action(cptype);
> }
>
> static int lkdtm_register_cpoint(enum cname which)
lkdtm_handler() can be called from module IRQ handlers, so perhaps the
same problems can still happen. The patch does improve things though ;)
next prev parent reply other threads:[~2012-01-30 20:54 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-28 12:52 [Patch] lkdtm: avoid calling lkdtm_do_action() with spin lock held Cong Wang
2012-01-29 1:15 ` Dave Young
2012-01-30 20:54 ` Andrew Morton [this message]
2012-01-31 13:25 ` Cong Wang
2012-01-31 15:35 ` Arnd Bergmann
2012-02-01 3:01 ` Cong Wang
2012-02-01 15:29 ` Arnd Bergmann
2012-02-02 13:31 ` Cong Wang
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