From: Rusty Russell <rusty@rustcorp•com.au>
To: Miche Baker-Harvey <miche@google•com>,
Greg Kroah-Hartman <gregkh@suse•de>
Cc: Stephen Rothwell <sfr@canb•auug.org.au>,
xen-devel@lists•xensource.com,
Konrad Rzeszutek Wilk <konrad.wilk@oracle•com>,
linux-kernel@vger•kernel.org,
virtualization@lists•linux-foundation.org,
Anton Blanchard <anton@samba•org>,
Amit Shah <amit.shah@redhat•com>,
Mike Waychison <mikew@google•com>,
ppc-dev <linuxppc-dev@lists•ozlabs.org>,
Eric Northrup <digitaleric@google•com>
Subject: Re: [PATCH v3 2/3] hvc_init(): Enforce one-time initialization.
Date: Fri, 11 Nov 2011 15:00:31 +1030 [thread overview]
Message-ID: <874nybqo0o.fsf@rustcorp.com.au> (raw)
In-Reply-To: <20111108214504.28884.61814.stgit@miche.sea.corp.google.com>
On Tue, 08 Nov 2011 13:45:04 -0800, Miche Baker-Harvey <miche@google•com> wrote:
> hvc_init() must only be called once, and no thread should continue with hvc_alloc()
> until after initialization is complete. The original code does not enforce either
> of these requirements. A new mutex limits entry to hvc_init() to a single thread,
> and blocks all later comers until it has completed.
>
> This patch fixes multiple crash symptoms.
No, it doesn't: not now your previous double-hvc_init patch has been
reverted.
It's easy to show this is the case though: replace mutex_lock() with:
if (!mutex_trylock()) {
WARN(1, "hvc_console: mutex is stopping us!\n");
mutex_lock();
}
If you get that warning, then your mutex is doing something.
Thanks,
Rusty.
next prev parent reply other threads:[~2011-11-11 4:30 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-08 21:44 [PATCH RFC v3 0/3] Support multiple VirtioConsoles Miche Baker-Harvey
2011-11-08 21:44 ` [PATCH v3 1/3] virtio_console: Fix locking of vtermno Miche Baker-Harvey
2011-11-11 4:27 ` Rusty Russell
2011-11-17 19:09 ` Amit Shah
2011-11-08 21:45 ` [PATCH v3 2/3] hvc_init(): Enforce one-time initialization Miche Baker-Harvey
2011-11-09 7:24 ` Michael Ellerman
2011-11-11 4:30 ` Rusty Russell [this message]
2011-11-17 18:57 ` Miche Baker-Harvey
2011-11-21 5:01 ` Rusty Russell
2011-11-21 22:16 ` Miche Baker-Harvey
2011-11-22 0:58 ` Rusty Russell
2011-11-23 10:38 ` Amit Shah
2011-11-23 12:56 ` Amit Shah
2011-11-23 13:06 ` Sasha Levin
2011-11-23 13:15 ` Amit Shah
2011-11-28 23:40 ` Miche Baker-Harvey
2011-11-29 14:21 ` Amit Shah
2011-11-29 17:04 ` Miche Baker-Harvey
2011-11-29 17:50 ` Miche Baker-Harvey
2011-12-05 10:54 ` Amit Shah
2011-12-06 17:05 ` Miche Baker-Harvey
2011-12-08 12:08 ` Amit Shah
2011-12-12 19:11 ` Miche Baker-Harvey
2011-12-12 19:25 ` Amit Shah
2011-12-16 6:00 ` Amit Shah
2011-11-08 21:45 ` [PATCH v3 3/3] Use separate struct console structure for each hvc_console Miche Baker-Harvey
2011-11-09 8:05 ` Michael Ellerman
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