From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH 15/17] fs: inode per-cpu last_ino allocator Date: Thu, 30 Sep 2010 09:53:09 +0200 Message-ID: <1285833189.2615.31.camel@edumazet-laptop> References: <1285762729-17928-1-git-send-email-david@fromorbit.com> <1285762729-17928-16-git-send-email-david@fromorbit.com> <20100929215312.5fcb6976.akpm@linux-foundation.org> <1285824982.5211.675.camel@edumazet-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Dave Chinner , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Andrew Morton Return-path: Received: from mail-fx0-f46.google.com ([209.85.161.46]:34581 "EHLO mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755081Ab0I3HxO (ORCPT ); Thu, 30 Sep 2010 03:53:14 -0400 In-Reply-To: <1285824982.5211.675.camel@edumazet-laptop> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Le jeudi 30 septembre 2010 =C3=A0 07:36 +0200, Eric Dumazet a =C3=A9cri= t : > Le mercredi 29 septembre 2010 =C3=A0 21:53 -0700, Andrew Morton a =C3= =A9crit : > > > +static unsigned int last_ino_get(void) > > > +{ > > > + static unsigned int last_ino; > > > + > > > + return ++last_ino; > > > +} > >=20 > > This is racy with CONFIG_PREEMPT on some architectures, I suspect. = I'd > > suggest conversion to atomic_t with, of course, an explanatory comm= ent ;) > >=20 >=20 In fact this code was OK when I submitted my original patch back in 2008, since it replaced fs/inode.c inode->i_ino =3D ++last_ino; And this was protected by a surrounding spinlock (spin_lock(&inode_lock); at that time) Even after Nick patches, preemption is still disabled (by two spinlocks... spin_lock(&sb_inode_list_lock); / spin_lock(&inode->i_lock);) So patch 15/17 seems good to me, I re-sign it as-is ;) Signed-off-by: Eric Dumazet If it happens preemption is re-enabled later (with future patches), we might need to change last_ino_get() too. Thanks ! -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel= " in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html