From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58549) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dqngP-0008Ci-6q for qemu-devel@nongnu.org; Sat, 09 Sep 2017 17:52:58 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dqngK-000093-BO for qemu-devel@nongnu.org; Sat, 09 Sep 2017 17:52:57 -0400 Date: Sat, 9 Sep 2017 18:52:43 -0300 From: Eduardo Habkost Message-ID: <20170909215243.GK7570@localhost.localdomain> References: <20170901110332.32650-1-otubo@redhat.com> <20170901143016.GK7570@localhost.localdomain> <87lglyzb3p.fsf@dusky.pond.sub.org> <20170901154430.GN7570@localhost.localdomain> <20170907083829.GB2441@vader> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170907083829.GB2441@vader> Subject: Re: [Qemu-devel] [Qemu-trivial] [PATCH] dma/i82374: avoid double creation of i82374 device List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eduardo Otubo Cc: Markus Armbruster , mst@redhat.com, qemu-trivial@nongnu.org, qemu-devel@nongnu.org, Alexander Graf , qemu-ppc@nongnu.org, pbonzini@redhat.com, David Gibson On Thu, Sep 07, 2017 at 10:38:29AM +0200, Eduardo Otubo wrote: > On Fri, Sep 01, 2017 at 12:44:30PM -0300, Eduardo Habkost wrote: > > On Fri, Sep 01, 2017 at 05:34:34PM +0200, Markus Armbruster wrote: > > > Eduardo Habkost writes: > > > > On Fri, Sep 01, 2017 at 01:03:32PM +0200, Eduardo Otubo wrote: [...] > > > >> diff --git a/hw/dma/i82374.c b/hw/dma/i82374.c > > > >> index 6c0f975df0..5275d822e0 100644 > > > >> --- a/hw/dma/i82374.c > > > >> +++ b/hw/dma/i82374.c > > > >> @@ -139,6 +139,7 @@ static void i82374_class_init(ObjectClass *klass, void *data) > > > >> dc->realize = i82374_realize; > > > >> dc->vmsd = &vmstate_i82374; > > > >> dc->props = i82374_properties; > > > >> + dc->user_creatable = false; > > > > > > > > A "Reason:" comment explaining why user_creatable=false is > > > > mandatory. See the comment above user_creatable declaration in > > > > qdev-core.h for reference. > > > > > > > > I suggest the following: > > > > > > > > /* > > > > * Reason: i82374_realize() crashes (assertion failure inside isa_bus_dma() > > > > * if the device is instantiated twice. > > > > */ > > I agree with the comment above. If there's nothing left to fix/add > I'll just send a v2 for this shortly. I suggest amending it with the additional info below, explaining that isa_bus_dma() isn't supposed to be called twice, and that we need to make isa_bus_dma()/DMA_init()/i82374_realize() return an appropriate error if the device is instantiated twice. > > > > > > > We need to find out *why* it crashes. Once we know, we can likely write > > > a better comment. > > > > It crashes because isa_bus_dma() isn't supposed to be called > > twice for the same bus. > > > > Making isa_bus_dma()/DMA_init()/i82374_realize() return an error > > instead of asserting would be even better than setting > > user_creatable=false. > > > > -- > > Eduardo > > > > -- > Eduardo Otubo > Senior Software Engineer @ RedHat -- Eduardo