From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta12.messagelabs.com (mail6.bemta12.messagelabs.com [216.82.250.247]) by kanga.kvack.org (Postfix) with ESMTP id EBE896B0096 for ; Thu, 24 Nov 2011 04:50:22 -0500 (EST) Message-ID: <1322128199.2921.3.camel@twins> Subject: Re: Fwd: uprobes: register/unregister probes. From: Peter Zijlstra Date: Thu, 24 Nov 2011 10:49:59 +0100 In-Reply-To: <20111124070303.GB28065@linux.vnet.ibm.com> References: <603b0079-5f54-4299-9a9a-a5e237ccca73@l23g2000pro.googlegroups.com> <20111124070303.GB28065@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Mime-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: Srikar Dronamraju Cc: Linus Torvalds , Oleg Nesterov , Andrew Morton , LKML , Linux-mm , Ingo Molnar , Andi Kleen , Christoph Hellwig , Steven Rostedt , Roland McGrath , Thomas Gleixner , Masami Hiramatsu , Arnaldo Carvalho de Melo , Anton Arapov , Ananth N Mavinakayanahalli , Jim Keniston , tulasidhard@gmail.com On Thu, 2011-11-24 at 12:33 +0530, Srikar Dronamraju wrote: > > On Fri, 2011-11-18 at 16:37 +0530, Srikar Dronamraju wrote: > > > +int register_uprobe(struct inode *inode, loff_t offset, > > > + struct uprobe_consumer *consumer) > > > +{ > > > + struct uprobe *uprobe; > > > + int ret =3D -EINVAL; > > > + > > > + if (!consumer || consumer->next) > > > + return ret; > > > + > > > + inode =3D igrab(inode); > >=20 > > So why are you dealing with !consumer but not with !inode? and why > > does > > it make sense to allow !consumer at all? > >=20 >=20 >=20 > I am not sure if I got your comment correctly. >=20 > I do check for inode just after the igrab. No you don't, you check the return value of igrab(), but you crash hard when someone calls register_uprobe(.inode=3DNULL). > I am actually not dealing with !consumer. > If the consumer is NULL, then we dont have any handler to run so why > would we want to register such a probe? Why allow someone calling register_uprobe(.consumer=3DNULL) to begin with? That doesn't make any sense. > Also if consumer->next is Non-NULL, that means that this consumer was > already used. Reusing the consumer, can result in consumers list getting > broken into two. Yeah, although at that point why be nice about it? Just but a WARN_ON() in or so. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org