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-core@gna.org >>> <Xenomai-core@gna.org >>>> R=dnslookup T=remote_smtp: SMTP error from remote mailer after RCPT >>>> TO:<Xenomai- >>> [EMAIL PROTECTED]>: 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 registry is also about providing user-safe handles for unnamed object - so that you don't risk accepting borken kernel pointers from user space. Jan
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