From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e28smtp03.in.ibm.com (e28smtp03.in.ibm.com [125.16.236.3]) (using TLSv1.2 with cipher CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id A68631A074D for ; Tue, 1 Mar 2016 15:34:16 +1100 (AEDT) Received: from localhost by e28smtp03.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 1 Mar 2016 10:04:13 +0530 Received: from d28av05.in.ibm.com (d28av05.in.ibm.com [9.184.220.67]) by d28relay05.in.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u214Y87U19005880 for ; Tue, 1 Mar 2016 10:04:08 +0530 Received: from d28av05.in.ibm.com (localhost [127.0.0.1]) by d28av05.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u214Y9WO012903 for ; Tue, 1 Mar 2016 10:04:10 +0530 Message-ID: <56D51BC1.7050904@linux.vnet.ibm.com> Date: Tue, 01 Mar 2016 10:04:09 +0530 From: Anshuman Khandual MIME-Version: 1.0 To: Tyrel Datwyler , linuxppc-dev@lists.ozlabs.org CC: aneesh.kumar@linux.vnet.ibm.com Subject: Re: [PATCH] powerpc/lpar: Don't crash on H_PROTECT errors References: <1456746752-9298-1-git-send-email-khandual@linux.vnet.ibm.com> <56D476DD.9060402@linux.vnet.ibm.com> In-Reply-To: <56D476DD.9060402@linux.vnet.ibm.com> Content-Type: text/plain; charset=utf-8 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 02/29/2016 10:20 PM, Tyrel Datwyler wrote: > On 02/29/2016 03:52 AM, Anshuman Khandual wrote: >> There are certain condition in which H_PROTECT can return error code >> other than H_NOT_FOUND and H_SUCCESS. One such being an attempt to >> update an hpte owned by adjunct partition. Return 0 in that case so >> that user space will retry the access. In adjunct case this mean we >> will not make much progress in the user space. But atleast we get a >> chance to kill the task and avoid taking down the entire box. >> >> Signed-off-by: Aneesh Kumar K.V >> Signed-off-by: Anshuman Khandual >> --- >> arch/powerpc/platforms/pseries/lpar.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c >> index 477290a..31bcdaf 100644 >> --- a/arch/powerpc/platforms/pseries/lpar.c >> +++ b/arch/powerpc/platforms/pseries/lpar.c >> @@ -310,7 +310,7 @@ static long pSeries_lpar_hpte_updatepp(unsigned long slot, >> >> pr_devel("ok\n"); >> >> - BUG_ON(lpar_rc != H_SUCCESS); >> + WARN_RATELIMIT(lpar_rc != H_SUCCESS, "H_PROTECT returned %lu\n", lpar_rc); > > In the event that we don't get H_NOT_FOUND (which is handled earlier in > the function) or H_SUCCESS this patch assumes H_RESOURCE. It fails to > handle H_PARAMETER which is also a valid return from the H_PROTECT > hypercall. Right, I guess its okay to BUG_ON() if we detect H_PARAMETER return code as the kernel should not have created wrong arguments to the hcall in the first place. Although we will still want to return 0 from here for H_RESOURCE return code with a WARN_RATELIMIT message. Will change the code accordingly next time around.