From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp04.au.ibm.com (e23smtp04.au.ibm.com [202.81.31.146]) (using TLSv1 with cipher CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id A79711A001B for ; Thu, 14 May 2015 09:28:50 +1000 (AEST) Received: from /spool/local by e23smtp04.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 14 May 2015 09:28:49 +1000 Received: from d23relay06.au.ibm.com (d23relay06.au.ibm.com [9.185.63.219]) by d23dlp01.au.ibm.com (Postfix) with ESMTP id 1DBE12CE8040 for ; Thu, 14 May 2015 09:28:44 +1000 (EST) Received: from d23av01.au.ibm.com (d23av01.au.ibm.com [9.190.234.96]) by d23relay06.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id t4DNSZrO29819114 for ; Thu, 14 May 2015 09:28:43 +1000 Received: from d23av01.au.ibm.com (localhost [127.0.0.1]) by d23av01.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id t4DNSA9u031182 for ; Thu, 14 May 2015 09:28:11 +1000 Date: Thu, 14 May 2015 09:27:45 +1000 From: Gavin Shan To: Thomas Huth Subject: Re: [PATCH kernel v10 05/34] powerpc/iommu: Always release iommu_table in iommu_free_table() Message-ID: <20150513232745.GA8158@gwshan> Reply-To: Gavin Shan 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20150513145136.1a85f536@thh440s> Cc: Wei Yang , Alexey Kardashevskiy , Gavin Shan , 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 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); Thanks, Gavin