Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753213AbbK3Hmf (ORCPT ); Mon, 30 Nov 2015 02:42:35 -0500 Received: from dgate10.ts.fujitsu.com ([80.70.172.49]:35093 "EHLO dgate10.ts.fujitsu.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752518AbbK3Hmc (ORCPT ); Mon, 30 Nov 2015 02:42:32 -0500 DomainKey-Signature: s=s1536a; d=ts.fujitsu.com; c=nofws; q=dns; h=X-SBRSScore:Received:Received:From:To:CC:Date:Subject: Thread-Topic:Thread-Index:Message-ID:References: In-Reply-To:Accept-Language:Content-Language: X-MS-Has-Attach:X-MS-TNEF-Correlator:acceptlanguage: Content-Type:Content-Transfer-Encoding:MIME-Version; b=HS0h0cigPGS6Lot9f7gQqY/NrOWQOyjlEUvJSSaT6qmKt/GK9U5cqwyY gcolLK94he52cTADjWLykrqwIq7IlQf+Jq+UpUXW2avKhahfRHg8rnatY fzEsA3Ozc7NReQ71mAEcZKQjQRuYHrenkTOD8bpVkxmZFUcHtSypz6lsJ 446pqHTUd2MRLIChOJkjz55Jw7BkvTmTnu6V/RiMAKYR9zEO3OoKaO+fO qgSC9dA3OY6OwRR+Biye5S/IQ5HHZ; X-SBRSScore: None From: "Wilck, Martin" To: =?utf-8?B?VXdlIEtsZWluZS1Lw7ZuaWc=?= CC: "gregkh@linuxfoundation.org" , "linux-kernel@vger.kernel.org" , "tpmdd-devel@lists.sourceforge.net" , Jason Gunthorpe Date: Mon, 30 Nov 2015 08:42:16 +0100 Subject: Re: [PATCH] base/platform: fix panic when probe function is NULL Thread-Topic: [PATCH] base/platform: fix panic when probe function is NULL Thread-Index: AdErQqJnAKHMmi1YQNC8Ny2wR+UclA== Message-ID: References: <1448564494-23218-1-git-send-email-martin.wilck@ts.fujitsu.com> <20151127101125.GS19888@pengutronix.de> In-Reply-To: <20151127101125.GS19888@pengutronix.de> Accept-Language: de-DE, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: de-DE, en-US Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id tAU7ge1S017278 Content-Length: 3841 Lines: 108 Hello Uwe, thanks for your review. > This may cause a panic later. For example, inserting the tpm_tis > > driver with parameter "force=1" (i.e. registering tpm_tis as a platform > > driver) will panic in tpmm_chip_alloc() because dev->driver is NULL: > > > > chip->cdev.owner = chip->pdev->driver->owner; > > This sounds like a separate issue though. Looking at init_tis there is: > > rc = platform_driver_register(&tis_drv); > if (rc < 0) > return rc; > pdev = platform_device_register_simple("tpm_tis", -1, NULL, 0); > if (IS_ERR(pdev)) { > rc = PTR_ERR(pdev); > goto err_dev; > } > rc = tpm_tis_init(&pdev->dev, &tis_default_info, NULL); > > tpm_tis_init calls tpmm_chip_alloc which barfs when pdev (i.e. the return value > of platform_device_register_simple above) isn't bound. It is not allowed > to assume that the device is bound after the above function calls. I agree that the TPM platform device code deserves improvement. Jason wrote that he has already some patches available for that. I lack the knowledge to judge whether or not tpm_is_init's assumption was correct. But, maybe just by luck, this assumption used to be *true* until patch b8b2c7d845d5. Driver and device were matched by name ("tpm_tis") by the platform driver probing code, and device and driver were actually bound to each other after this sequence of calls. > So I'd say drop the paragraph about tpm_tis and the change is fine. I didn't mean to blame your patch. But a note about the panic might be helpful just in case someone else runs into the same problem. The connection between your patch and tpm_tis loading is far from obvious. I mentioned the panic in order to clarify that this wasn't just a theoretical issue. Anyway, I'll resubmit with your style hints applied and will try to find a wording for the commit message that we can agree upon. Best Regards, Martin > > > This patch fixes this by returning success in platform_drv_probe() if > > "just" dev_pm_domain_attach() had failed. This restores the semantics > > of platform_device_register_XXX() if the associated platform driver has > > no "probe" function. > > > > Fixes: b8b2c7d845d5 ("base/platform: assert that dev_pm_domain > > callbacks are called unconditionally") > > > > I think line breaks in the Fixes: line are frowned on. Also usually > there is no empty line between Fixes: and S-o-b:. > > > Signed-off-by: Martin Wilck > > --- > > drivers/base/platform.c | 12 ++++++++---- > > 1 file changed, 8 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/base/platform.c b/drivers/base/platform.c > > index 1dd6d3b..c994e76 100644 > > --- a/drivers/base/platform.c > > +++ b/drivers/base/platform.c > > @@ -513,10 +513,14 @@ static int platform_drv_probe(struct device *_dev) > > return ret; > > > > ret = dev_pm_domain_attach(_dev, true); > > - if (ret != -EPROBE_DEFER && drv->probe) { > > - ret = drv->probe(dev); > > - if (ret) > > - dev_pm_domain_detach(_dev, true); > > + if (ret != -EPROBE_DEFER) { > > + if (drv->probe) { > > + ret = drv->probe(dev); > > + if (ret) > > + dev_pm_domain_detach(_dev, true); > > + } else > > + /* don't fail if just dev_pm_domain_attach failed */ > > + ret = 0; > > An else that has a } should also have a {, according to > checkpatch and Documentation/CodingStyle. You can write it > alternatively as: > > if (ret != -EPROBE_DEFER) { > if (drv->probe) > ret = drv->probe(dev); > else > ret = 0; > > if (ret) > dev_pm_domain_detach(_dev, true); > } > > . > > Best regards > Uwe > ????{.n?+???????+%?????ݶ??w??{.n?+????{??G?????{ay?ʇڙ?,j??f???h?????????z_??(?階?ݢj"???m??????G????????????&???~???iO???z??v?^?m???? ????????I?