From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <48AFF17F.1080803@domain.hid> Date: Sat, 23 Aug 2008 13:16:15 +0200 From: Philippe Gerum MIME-Version: 1.0 References: <48AFCB3F.6070902@domain.hid> <48AFE498.2060805@domain.hid> <48AFEC44.8000407@domain.hid> <48AFEF7C.8090503@domain.hid> In-Reply-To: <48AFEF7C.8090503@domain.hid> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Xenomai-core] Racy pse51_mutex_check_init? Reply-To: rpm@xenomai.org List-Id: "Xenomai life and development \(bug reports, patches, discussions\)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gilles Chanteperdrix Cc: Xenomai-core@domain.hid Gilles Chanteperdrix wrote: > Philippe Gerum wrote: >> Gilles Chanteperdrix wrote: >>> Hi Jan, >>> >>> Please do not use my address at gmail, gna does not want me to post from >>> this address: >>> >>> 2008-08-23 12:10:19 1KWq4T-0000zD-9E ** xenomai@xenomai.org >>> R=dnslookup T=remote_smtp: SMTP error from remote mailer after RCPT TO:>> core@domain.hid>: host mail.gna.org [88.191.250.46]: 550 rejected because gmail.com i >>> s in a black list at dsn.rfc-ignorant.org >>> >>> so, here is a repost of my answer: >>> >>> Jan Kiszka wrote: >>>>> Hi Gilles, >>>>> >>>>> trying to understand the cb_read/write lock usage, some question came up >>>>> here: What prevents that the mutexq iteration in pse51_mutex_check_init >>>>> races against pse51_mutex_destroy_internal? >>> Well, I am afraid the mechanism used is not 100% safe. Anyway, the aim >>> is to catch most of invalid usages, it seems we can not catch them all. >>> >>>>> If nothing, then I wonder if we actually have to iterate over the whole >>>>> queue to find out whether a given object has been initialized and >>>>> registered already or not. Can't this be encoded differently? >>>>> >>>>> BTW, shadow_mutex.mutex is a kernel pointer sitting in a user-reachable >>>>> memory region? Why not using a handle here, like the native skin does? >>>>> Won't that allow to resolve the issue above as well? >>> This has been so from the beginning, and I did not change it. >>> >> To get registry handles, you first need to register objects. The POSIX skin >> still does not use the built-in registry, that's why. > > Well the registry is about associating objects with their name, and > since most posix skin objects have no name, I did not see the point of > using the registry. And for the named objects, the nucleus registry was > not compatible with the posix skin requirements, which is why I did not > use it... > The thing is that, without built-in registry support, you have no /proc export of any status data either. -- Philippe.