On 12/21/05, pradeep singh <2500.pradeep@xxxxxxxxx> wrote: > > > On 12/21/05, Badari Prasad <h.badari@xxxxxxxxx> wrote: > > Hello, > > I have a Query regarding semaphores, is semaphores a mandatory > lock mechanism ( like lockf() ) ,or an advisory lock mechanism ( like flock > () ). > > it is a mandatory lock mechanishm , where the requesting process checks > for a value to get positive ( as semaphores r initalised to a value > depending on usage ...AFAIR ..plz CMIIW) , there r generally 2 operations on > them. > [Please: s/r/are/ , s/plz/please/] You are wrong. Kernel semaphores are, as Matthew Wilcox already answered, advisory locks. Nothing at all is stopping you from accessing data protected by a semaphore - bad things will probably happen but nothing stops you from crashing your kernel that way. > sem wait and sem post. > check any book on linux prograaming on their implementation.... > > good luck > > > > If it is an advisory lock mechanism, in which situation the lock > be ignored by the other process ( say process2 ) trying to access the data > which is locked by process1. > > > > Thank you, > > Badari. > > -- Jesper Juhl <jesper.juhl@xxxxxxxxx> Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html Plain text mails only, please http://www.expita.com/nomime.html -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
