linux-kernel - Re: [RFC PATCH v2] posix timers: allocate timer id per task

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1350481466.26103.464.camel@edumazet-glaptop>
Date:	Wed, 17 Oct 2012 15:44:26 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Stanislav Kinsbursky <skinsbursky@...allels.com>
Cc:	peterz@...radead.org, mingo@...hat.com, tglx@...utronix.de,
	linux-kernel@...r.kernel.org, devel@...nvz.org
Subject: Re: [RFC PATCH v2] posix timers: allocate timer id per task

On Wed, 2012-10-17 at 17:18 +0400, Stanislav Kinsbursky wrote:

> +static int hash(struct signal_struct *sig, unsigned int nr)
> +{
> +	int hash = hash_ptr(sig, POSIX_TIMERS_HASH_BITS);
> +	return hash ^ hash_32(nr, POSIX_TIMERS_HASH_BITS);
> +}
> +

This is quite expensive on 64 bit arches. I suggest instead :

return hash_32(hash32_ptr(sig) ^ nr, POSIX_TIMERS_HASH_BITS);


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/