On Fri, Apr 25, 2008 at 3:42 PM, Philippe Gerum <[EMAIL PROTECTED]> wrote: > > Gilles Chanteperdrix wrote: > > On Fri, Apr 25, 2008 at 9:48 AM, Philippe Gerum <[EMAIL PROTECTED]> wrote: > >> Gilles Chanteperdrix wrote: > >> > This patch implements the _read, _set, and _cmpxchg operations on > atomic_long_t > >> > and atomic_ptr_t in user-space in include/asm-generic/atomic.h which > should be > >> > included at the end of include/asm-*/atomic.h after the definition of > the same > >> > operations for the atomic_t type and atomic64_t type on 64 bits > platforms. > >> > > >> > These operations are the basic operations used by user-space mutexes. > Maybe we > >> > should add the xnarch_ prefix ? > >> > > >> > >> Yes, but more generally, we should rework this to fit the existing atomic > >> support in include/asm-*/atomic.h, so that we don't end up with sideways > to what > >> has been already designed to support set, get, xchg and the like, in > both kernel > >> and userland context. > > > > That is not exactly sideways... Linux include/asm-generic/atomic.h > > defines operations for atomic_long_t. This file adds two things: > > - support for atomic_long_t in user-space (where we can not include > > linux include/asm-generic/atomic.h) > > - support for a new type atomic_ptr_t both to kernel-space and > > user-space, the aim is to avoid all the casts that would take place if > > we wanted to use atomic_long_t to store pointers. > > > > However for this file to work, it has to be included by asm-*/atomic.h > > after the definition of atomic_t (and atomic64_t on 64 bits > > platforms). So linux includes asm-generic/atomic.h at the end of > > asm/atomic.h, I simply reproduced this scheme with Xenomai > > include/asm-*/atomic.h. > > > > Focusing on user-space: 1) xnarch_atomic_xchg is meant to work on long > types; 2) > set, get routines are not defined in that scope. If the purpose is to define > integer-type ops to handle pointer-type data atomically (i.e. intptr_t), > then I > would rather check whether we actually need non-long support at all in > user-space. In case we don't, I would simply reply on the existing > implementation of asm-*/atomic.h + the set / get extensions you provide.
I use both atomic_t and atomic_ptr_t for the implementation of user-space mutexes. The problem is that I am constrained by the size of pthread_mutex_t, so the "control block read-write locks" implementation use atomic_t. -- Gilles _______________________________________________ Xenomai-core mailing list Xenomai-core@gna.org https://mail.gna.org/listinfo/xenomai-core
