Very nice!
2013/2/7 Peter Teoh <htmldevelo...@gmail.com> > Multiple concurrent write() by different thread is possible, as they all > can share the same file descriptor in a single similar process, and this is > not allowed. So nevertheless, the problem you posed is not > allowed/acceptable by the kernel, so Linus himself fixed it: > > See here: > > http://lwn.net/Articles/180387/ > > And Linus patch: > > http://lwn.net/Articles/180396/ > > but my present version (3.2.0) has rcu lock over it (higher performance): > > INIT_LIST_HEAD(&f->f_u.fu_list); > atomic_long_set(&f->f_count, 1); > rwlock_init(&f->f_owner.lock); > spin_lock_init(&f->f_lock); > eventpoll_init_file(f); > /* f->f_version: 0 */ > > > On Thu, Feb 7, 2013 at 4:44 PM, Karaoui mohamed lamine < > mohar...@gmail.com> wrote: > >> >> Tahnks guys! >> >> 2013/1/30 Karaoui mohamed lamine <mohar...@gmail.com> >> >>> thanks, i think i get it. >>> >>> 2013/1/30 <valdis.kletni...@vt.edu> >>> >>> On Tue, 29 Jan 2013 20:16:26 +0100, you said: >>>> >>>> > Actually my question is : >>>> > Does POSIX specifies the fact that we need to use "lockf" to be able >>>> to do >>>> > read/write operation in different offset ? Is'n the kernel supposed to >>>> > ensure this ? >>>> >>>> If you have non-overlapping writes, the kernel will eventually sort it >>>> out >>>> for you. If your writes overlap, you'll have to provide your own >>>> locking >>>> via lockf() or similar, and synchronization via other methods. >>>> >>> >>> >> >> _______________________________________________ >> Kernelnewbies mailing list >> Kernelnewbies@kernelnewbies.org >> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies >> >> > > > -- > Regards, > Peter Teoh >
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