From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36381) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dnMZ9-0004cA-GR for qemu-devel@nongnu.org; Thu, 31 Aug 2017 06:19:18 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dnMZ4-0006uX-Ia for qemu-devel@nongnu.org; Thu, 31 Aug 2017 06:19:15 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:33963 helo=mx0a-001b2d01.pphosted.com) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dnMZ4-0006uI-9E for qemu-devel@nongnu.org; Thu, 31 Aug 2017 06:19:10 -0400 Received: from pps.filterd (m0098413.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v7VAIsng048290 for ; Thu, 31 Aug 2017 06:19:09 -0400 Received: from e06smtp14.uk.ibm.com (e06smtp14.uk.ibm.com [195.75.94.110]) by mx0b-001b2d01.pphosted.com with ESMTP id 2cpbh8hmfq-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Thu, 31 Aug 2017 06:19:09 -0400 Received: from localhost by e06smtp14.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 31 Aug 2017 11:19:07 +0100 References: <20170830163609.50260-1-pasic@linux.vnet.ibm.com> <20170830163609.50260-2-pasic@linux.vnet.ibm.com> <20170831083859.11694707.cohuck@redhat.com> <20170831104243.43cd8992.cohuck@redhat.com> From: Halil Pasic Date: Thu, 31 Aug 2017 12:19:04 +0200 MIME-Version: 1.0 In-Reply-To: <20170831104243.43cd8992.cohuck@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Message-Id: Subject: Re: [Qemu-devel] [PATCH 1/9] s390x/css: fix cc handling for XSCH List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Cornelia Huck , Thomas Huth Cc: Pierre Morel , Dong Jia Shi , qemu-devel@nongnu.org On 08/31/2017 10:42 AM, Cornelia Huck wrote: > On Thu, 31 Aug 2017 09:32:49 +0200 > Thomas Huth wrote: > >> On 31.08.2017 08:38, Cornelia Huck wrote: >>> On Thu, 31 Aug 2017 07:51:17 +0200 >>> Thomas Huth wrote: >>> >>>> On 30.08.2017 18:36, Halil Pasic wrote: >>>>> The function ioinst_handle_xsch is presenting cc 2 when it's supposed to >>>>> present cc 1 and the other way around, because css_do_xsch has the error >>>>> codes mixed up. Fixing the error codes also fixes the priority. >>>>> >>>>> Let us fix this. >>>> >>>> (Nit: In case you respin, I'd suggest to remove the last sentence. You >>>> already used "fix" two times in the previous one) >>> >>> I can also remove it on applying, if Halil agrees (I have not yet >>> reviewed it, though). >>> >>>> >>>>> Signed-off-by: Halil Pasic >>>>> Reported-by: Pierre Morel >>>> >>>> Space missing -------------^ >>> >>> And I can also add that space on applying :) >>> >>>> >>>>> --- >>>>> hw/s390x/css.c | 4 ++-- >>>>> 1 file changed, 2 insertions(+), 2 deletions(-) >>>>> >>>>> diff --git a/hw/s390x/css.c b/hw/s390x/css.c >>>>> index 1880b1a0ff..a50fb0727e 100644 >>>>> --- a/hw/s390x/css.c >>>>> +++ b/hw/s390x/css.c >>>>> @@ -1281,12 +1281,12 @@ int css_do_xsch(SubchDev *sch) >>>>> (!(s->ctrl & >>>>> (SCSW_ACTL_RESUME_PEND | SCSW_ACTL_START_PEND | SCSW_ACTL_SUSP))) || >>>>> (s->ctrl & SCSW_ACTL_SUBCH_ACTIVE)) { >>>>> - ret = -EINPROGRESS; >>>>> + ret = -EBUSY; >>>>> goto out; >>>>> } >>>>> >>>>> if (s->ctrl & SCSW_CTRL_MASK_STCTL) { >>>>> - ret = -EBUSY; >>>>> + ret = -EINPROGRESS; >>>>> goto out; >>>>> } >>>> >>>> Using both, EBUSY and EINPROGRESS as error codes sounds very confusing >>>> to me here ... what's the difference between busy and in-progress? So >>>> while you're at it, maybe you could replace the code for CC 2 ("CANCEL >>>> SUBCHANNEL not applicable") with a different error code? >>> >>> IIRC, I used these two as they matched my idea of what happens best >>> (there's a difference between "subchannel is busy" and "the I/O is >>> already in progress, too late to cancel"). "xsch not applicable" is >>> very hard to translate to an Unix error code :/ >> >> OK, the codes make more sense with your description ==> Maybe simply add >> a proper comment for each of the return codes? > > Taking a step back and looking at the other I/O instructions and their > implementation in qemu: > > - For those instructions that can set it, cc 1 is set when the > subchannel is status pending. That's usually the "default" branch in > ioinst.c. > - cc 2 is set when the subchannel is "busy" (or, in the case of xsch, > "not applicable for xsch"... sigh) This is supposed to be handled via > -EBUSY. > > So, there are actually two problems with the current implementation of > xsch: > > - The return codes are switched around, which this patch fixes. > - But "status pending" should also take precedence over "not > applicable", if I read the PoP correctly, so the second if needs to > be moved up. You are right and I was wrong. "Condition code 1 has precedence over condition code 2." So it's 3 > 1 > 2 (and I remembered 3 > 2 > 1). I will fix this for v2. > > And yes, it makes sense do add some comments... > If we apply the series as a whole adding comments would an overkill IMHO. We will switch this to iret.cc = ? so it should become obvious.