From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f174.google.com (mail-pd0-f174.google.com [209.85.192.174]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 92FA61A0015 for ; Thu, 14 May 2015 12:34:43 +1000 (AEST) Received: by pdbqa5 with SMTP id qa5so69822889pdb.1 for ; Wed, 13 May 2015 19:34:41 -0700 (PDT) Message-ID: <555409B8.3060904@ozlabs.ru> Date: Thu, 14 May 2015 12:34:32 +1000 From: Alexey Kardashevskiy MIME-Version: 1.0 To: Gavin Shan , Thomas Huth Subject: Re: [PATCH kernel v10 05/34] powerpc/iommu: Always release iommu_table in iommu_free_table() References: <1431358763-24371-1-git-send-email-aik@ozlabs.ru> <1431358763-24371-6-git-send-email-aik@ozlabs.ru> <20150513053337.GA479@gwshan> <5552EF78.6020301@ozlabs.ru> <20150513145136.1a85f536@thh440s> <20150513232745.GA8158@gwshan> In-Reply-To: <20150513232745.GA8158@gwshan> Content-Type: text/plain; charset=koi8-r; format=flowed Cc: Wei Yang , linux-kernel@vger.kernel.org, Alex Williamson , Paul Mackerras , linuxppc-dev@lists.ozlabs.org, David Gibson List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 05/14/2015 09:27 AM, Gavin Shan wrote: > On Wed, May 13, 2015 at 02:51:36PM +0200, Thomas Huth wrote: >> On Wed, 13 May 2015 16:30:16 +1000 >> Alexey Kardashevskiy wrote: >> >>> On 05/13/2015 03:33 PM, Gavin Shan wrote: >>>> On Tue, May 12, 2015 at 01:38:54AM +1000, Alexey Kardashevskiy wrote: >>>>> At the moment iommu_free_table() only releases memory if >>>>> the table was initialized for the platform code use, i.e. it had >>>>> it_map initialized (which purpose is to track DMA memory space use). >>>>> >>>>> With dynamic DMA windows, we will need to be able to release >>>>> iommu_table even if it was used for VFIO in which case it_map is NULL >>>>> so does the patch. >>>>> >>>>> Signed-off-by: Alexey Kardashevskiy >>>> >>>> Reviewed-by: Gavin Shan >>>> >>>>> --- >>>>> arch/powerpc/kernel/iommu.c | 3 +-- >>>>> 1 file changed, 1 insertion(+), 2 deletions(-) >>>>> >>>>> diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c >>>>> index 3d47eb3..2c02d4c 100644 >>>>> --- a/arch/powerpc/kernel/iommu.c >>>>> +++ b/arch/powerpc/kernel/iommu.c >>>>> @@ -714,8 +714,7 @@ void iommu_free_table(struct iommu_table *tbl, const char *node_name) >>>>> unsigned int order; >>>>> >>>>> if (!tbl || !tbl->it_map) { >>>>> - printk(KERN_ERR "%s: expected TCE map for %s\n", __func__, >>>>> - node_name); >>>>> + kfree(tbl); >>>> >>>> I'm not sure if the "tbl" needs to be checked against NULL as kfree() already >>>> has the check. But it looks a bit strange to free NULL "tbl" from the code >>>> itself. >>> >>> Yeah, looks a bit weird, agree, I'll change but in general kfree/vfree/... >>> - they all check the passed pointer for NULL. >> >> But if tbl is NULL, the tbl->it_map check will fail, won't it? So in >> this case, I think you have to keep it. >> > > If I understood your question correctly, "tbl->it_map" won't be checked > when "tbl" is NULL because the connection ("||") for the two conditions. > The code can be changed to something like below if Alexey want: > > if (!tbl) > return; > if (!tbl->itmap) > kfree(tbl); To be precise ;) if (!tbl->itmap) { kfree(tbl); return; } > > Thanks, > Gavin > -- Alexey