From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Glauber Subject: Re: [PATCH 5/5] mmc: cavium: Fix probing race with regulator Date: Thu, 18 May 2017 11:39:24 +0200 Message-ID: <20170518093924.GA27614@hc> References: <20170516093655.17746-1-jglauber@cavium.com> <20170516093655.17746-6-jglauber@cavium.com> <20170516133838.GA20659@hc> <20170517134112.GA6216@hc> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-by2nam01on0076.outbound.protection.outlook.com ([104.47.34.76]:40829 "EHLO NAM01-BY2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751548AbdERJjh (ORCPT ); Thu, 18 May 2017 05:39:37 -0400 Content-Disposition: inline In-Reply-To: <20170517134112.GA6216@hc> Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Rob Herring Cc: Ulf Hansson , David Daney , Frank Rowand , "Steven J . Hill" , "linux-mmc@vger.kernel.org" , "linux-kernel@vger.kernel.org" On Wed, May 17, 2017 at 03:41:12PM +0200, Jan Glauber wrote: > On Tue, May 16, 2017 at 09:37:48AM -0500, Rob Herring wrote: > > On Tue, May 16, 2017 at 8:38 AM, Jan Glauber > > wrote: > > > On Tue, May 16, 2017 at 08:07:50AM -0500, Rob Herring wrote: > > >> On Tue, May 16, 2017 at 4:36 AM, Jan Glauber wrote: > > >> > If the regulator probing is not yet finished this driver > > >> > might catch a -EPROBE_DEFER. Returning after this condition > > >> > did not remove the created platform device. On a repeated > > >> > call to the probe function the of_platform_device_create > > >> > fails. > > >> > > > >> > Calling of_platform_device_destroy after EPROBE_DEFER resolves > > >> > this bug. > > >> > > > >> > Signed-off-by: Jan Glauber > > >> > --- > > >> > drivers/mmc/host/cavium-thunderx.c | 4 +++- > > >> > 1 file changed, 3 insertions(+), 1 deletion(-) > > >> > > > >> > diff --git a/drivers/mmc/host/cavium-thunderx.c b/drivers/mmc/host/cavium-thunderx.c > > >> > index fe3d772..257535e 100644 > > >> > --- a/drivers/mmc/host/cavium-thunderx.c > > >> > +++ b/drivers/mmc/host/cavium-thunderx.c > > >> > @@ -137,8 +137,10 @@ static int thunder_mmc_probe(struct pci_dev *pdev, > > >> > continue; > > >> > > > >> > ret = cvm_mmc_of_slot_probe(&host->slot_pdev[i]->dev, host); > > >> > - if (ret) > > >> > + if (ret) { > > >> > + of_platform_device_destroy(&host->slot_pdev[i]->dev, NULL); > > >> > > >> What if this fails after the 1st iteration of the loop. It's only > > >> cleaning up the current device. > > > > > > The platform device is just a dummy device created directly before > > > cvm_mmc_of_slot_probe(). So there is no need to cleanup anything else. > > > > So if you have 2 slots, the first slot probes successfully and the 2nd > > slot defers, then you only need to clean-up the 2nd device/slot? Looks > > to me like you are leaking the 1st device you alloc. > > OK, got it now. My assumption was that your scenario can't happen in > reality with EPROBE_DEFER. > > > > > > > As far as I've seen it the platform code 'tags' the nodes it already > > > used, but I need the same node to be parsed again on -EPROBE_DEFER. > > > > > >> Use devm_of_platform_populate or > > >> of_platform_populate/of_platform_depopulate instead. > > > > > > I'm not sure one of these will work here. > > > > Those functions loop over child nodes and create devices. You are > > doing the same thing. You'd just need to create all the devices first > > and then probe them all. > > I'll take a look at devm_of_platform_populate then. If I can use it it > will solve the leak issue. Using [devm_]of_platform_populate/of_platform_depopulate would require a platform driver with its prove/remove functions. I don't think this would make the driver easier to read as we would then have a platform driver within a pci driver. If it is possible to export the of_platform_device_destroy() I would prefer to fix the leak and stay with of_platform_device_create. --Jan > thanks, > Jan > > > The whole structure here with the dummy devices and how you are > > initializing things is screwy. IMO, you should be creating actual > > drivers for the dummy devices. > > > > Rob