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From: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
To: Doug Ledford <dledford@redhat.com>
Cc: Dennis Dalessandro <dennis.dalessandro@intel.com>,
	Dan Carpenter <dan.carpenter@oracle.com>,
	Mike Marciniszyn <mike.marciniszyn@intel.com>,
	Sean Hefty <sean.hefty@intel.com>,
	Hal Rosenstock <hal.rosenstock@gmail.com>,
	linux-rdma@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: Re: [PATCH] IB/hfi1: Fix a wrapping test (make it less strict)
Date: Mon, 23 Oct 2017 13:04:00 -0600	[thread overview]
Message-ID: <20171023190400.GA24412@obsidianresearch.com> (raw)
In-Reply-To: <1508783626.3325.16.camel@redhat.com>

On Mon, Oct 23, 2017 at 02:33:46PM -0400, Doug Ledford wrote:
> > > > @@ -3781,7 +3781,7 @@ static int
> > > > __subn_get_opa_hfi1_cong_log(struct
> > > > opa_smp *smp, u32 am,
> > > >   		 * required to wrap the counter are supposed to
> > > >   		 * be zeroed (CA10-49 IBTA, release 1.2.1, V1).
> > > >   		 */
> > > > -		if ((u64)(ts - cce->timestamp) > (2 * UINT_MAX))
> > > > +		if ((u64)(ts - cce->timestamp) > (2ULL *
> > > > UINT_MAX))

This is really weird looking. Both ts and cce->timestamp are s64, why
do the convoluted conversion to unsigned? And surely UINT_MAX is not
the right thing..

if ((ts - cce->timestamp)/2 > 0xFFFFFFFF)

?

ktime_get is defined to be monotonic, so ts - cce->timestamp should
never go negative.

Jason

  reply	other threads:[~2017-10-23 19:04 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-13 10:56 [PATCH] IB/hfi1: Fix a wrapping test (make it less strict) Dan Carpenter
2017-10-23 15:05 ` Doug Ledford
     [not found]   ` <1508771116.3325.0.camel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2017-10-23 17:57     ` Dennis Dalessandro
2017-10-23 18:33       ` Doug Ledford
2017-10-23 19:04         ` Jason Gunthorpe [this message]
2017-10-24 19:54           ` Marciniszyn, Mike
     [not found]             ` <32E1700B9017364D9B60AED9960492BC3443EB1C-RjuIdWtd+YbTXloPLtfHfbfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2017-10-24 20:02               ` Jason Gunthorpe
     [not found]                 ` <20171024200216.GA15994-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2017-10-24 20:03                   ` Marciniszyn, Mike
2017-10-25  5:27                   ` Dan Carpenter
2017-10-25  5:14               ` Dan Carpenter

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