From: Colin Ian King <colin.king@canonical.com>
To: David Howells <dhowells@redhat.com>
Cc: linux-afs@lists.infradead.org, kernel-janitors@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH][next] afs: fix integer overflow when shifting 1 more than 32 places
Date: Wed, 11 Apr 2018 14:42:47 +0100 [thread overview]
Message-ID: <62e9abc2-b639-419c-afa7-e89054f7dce9@canonical.com> (raw)
In-Reply-To: <23535.1523453966@warthog.procyon.org.uk>
On 11/04/18 14:39, David Howells wrote:
> Colin King <colin.king@canonical.com> wrote:
>
>> Shifting 1 (a 32 bit signed int) more than 32 places will overflow
>> the int, so explicitly use 1ULL to avoid this overflow.
>> ...
>> - mask = (1 << nr_slots) - 1;
>> + mask = (1ULL << nr_slots) - 1;
>
> nr_slots cannot be larger than 9, so what I wrote is actually fine and is more
> efficient on a 32-bit machine.
ok, sorry about the noise.
>
> David
> --
> To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
WARNING: multiple messages have this Message-ID (diff)
From: Colin Ian King <colin.king@canonical.com>
To: David Howells <dhowells@redhat.com>
Cc: linux-afs@lists.infradead.org, kernel-janitors@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH][next] afs: fix integer overflow when shifting 1 more than 32 places
Date: Wed, 11 Apr 2018 13:42:47 +0000 [thread overview]
Message-ID: <62e9abc2-b639-419c-afa7-e89054f7dce9@canonical.com> (raw)
In-Reply-To: <23535.1523453966@warthog.procyon.org.uk>
On 11/04/18 14:39, David Howells wrote:
> Colin King <colin.king@canonical.com> wrote:
>
>> Shifting 1 (a 32 bit signed int) more than 32 places will overflow
>> the int, so explicitly use 1ULL to avoid this overflow.
>> ...
>> - mask = (1 << nr_slots) - 1;
>> + mask = (1ULL << nr_slots) - 1;
>
> nr_slots cannot be larger than 9, so what I wrote is actually fine and is more
> efficient on a 32-bit machine.
ok, sorry about the noise.
>
> David
> --
> To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
next prev parent reply other threads:[~2018-04-11 13:42 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-11 13:26 [PATCH][next] afs: fix integer overflow when shifting 1 more than 32 places Colin King
2018-04-11 13:26 ` Colin King
2018-04-11 13:39 ` David Howells
2018-04-11 13:39 ` David Howells
2018-04-11 13:42 ` Colin Ian King [this message]
2018-04-11 13:42 ` Colin Ian King
2018-04-11 14:10 ` David Howells
2018-04-11 14:10 ` David Howells
2018-04-11 14:17 ` Colin Ian King
2018-04-11 14:17 ` Colin Ian King
2018-04-11 15:58 ` Dan Carpenter
2018-04-11 15:58 ` Dan Carpenter
2018-04-11 16:03 ` David Howells
2018-04-11 16:03 ` David Howells
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