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From: David Laight <David.Laight@ACULAB.COM>
To: "'maninder1.s@samsung.com'" <maninder1.s@samsung.com>,
	Eric Dumazet <eric.dumazet@gmail.com>,
	"davem@davemloft.net" <davem@davemloft.net>,
	"shuahkh@osg.samsung.com" <shuahkh@osg.samsung.com>
Cc: "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"linux-api@vger.kernel.org" <linux-api@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"edumazet@google.com" <edumazet@google.com>,
	PANKAJ MISHRA <pankaj.m@samsung.com>,
	AMIT SAHRAWAT <a.sahrawat@samsung.com>,
	Vaneet Narang <v.narang@samsung.com>
Subject: RE: [PATCH 1/1] selftest/net: fix FILE_SIZE for 32 bit architecture.
Date: Fri, 3 Aug 2018 11:12:06 +0000
Message-ID: <4f2c8d694dce4125a609e8d5383ebe36@AcuMS.aculab.com> (raw)
In-Reply-To: <20180803033159epcms5p1dd2f5a6834268e9a22efa15421795fa0@epcms5p1>

From: Maninder Singh
> Sent: 03 August 2018 04:32
> >On 08/02/2018 03:31 AM, Maninder Singh wrote:
> >> FILE_SZ is defined as (1UL << 35), it will overflow
> >> for 32 bit system and logic will break.
> >>
> >> Signed-off-by: Maninder Singh <maninder1.s@samsung.com>
> >> Signed-off-by: Vaneet Narang <v.narang@samsung.com>
> >> ---
> >>  tools/testing/selftests/net/tcp_mmap.c | 8 ++++----
> >>  1 file changed, 4 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/tools/testing/selftests/net/tcp_mmap.c b/tools/testing/selftests/net/tcp_mmap.c
> >> index e8c5dff..1d6ca12 100644
> >> --- a/tools/testing/selftests/net/tcp_mmap.c
> >> +++ b/tools/testing/selftests/net/tcp_mmap.c
> >> @@ -85,7 +85,7 @@
> >>  #define MSG_ZEROCOPY    0x4000000
> >>  #endif
> >>
> >> -#define FILE_SZ (1UL << 35)
> >> +#define FILE_SZ (1ULL << 35)
> 
> ...
> ...
> >> @@ -431,7 +431,7 @@ int main(int argc, char *argv[])
> >>                  zflg = 0;
> >>          }
> >>          while (total < FILE_SZ) {
> >> -                long wr = FILE_SZ - total;
> >> +                unsigned long long wr = FILE_SZ - total;
> >>
> >>                  if (wr > chunk_size)
> >>                          wr = chunk_size;
> >>
> >
> >What about using more conventional size_t instead of "unsigned long long" ?
> 
> size_t is also equivalent to unsigned long and it will not hold value of (1 << 35) for 32 bit system.
> So we can do two things.

Wouldn't the 'correct' type be off_t ?
In any case, IIRC, you have to do really horrid things in Linux to
access files larger than 2G on 32bit systems.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

  reply index

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20180802103616epcas5p48ec1e2ea3568b11683aa7b55254dffb0@epcas5p4.samsung.com>
2018-08-02 10:31 ` Maninder Singh
2018-08-02 13:08   ` Eric Dumazet
     [not found]   ` <CGME20180802103616epcas5p48ec1e2ea3568b11683aa7b55254dffb0@epcms5p1>
2018-08-03  3:31     ` Maninder Singh
2018-08-03 11:12       ` David Laight [this message]
     [not found]       ` <CGME20180802103616epcas5p48ec1e2ea3568b11683aa7b55254dffb0@epcms5p4>
2018-08-10  6:03         ` Maninder Singh

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