On 07.09.2013 08:58:14, Samuel Thibault wrote: > Marin Ramesa, le Sat 07 Sep 2013 08:00:47 +0200, a écrit : > > * ipc/ipc_port.c (ipc_port_set_seqno) [MACH_SLOCKS]: Conditional > > locking. > > What is the rationale? Does it really bring an noticeable > improvement? The locking is already conditional inside > ipc_port_lock_mqueue, from the simple_*lock* macros themselves. That > is way more readable than having ifdefs inside the main source code.
That code in ipc_port_set_seqno() is simply not functional (except the change in sequence number) in the case when MACH_SLOCKS is not defined. We have a local variable mqueue that is set by the lock, but if you look at the definition of imq_unlock() and then simple_unlock() members of mqueue just change state and they don't have any effect on any other variable, plus it's a local variable - I would understand the code if mqueue is more global, but it's not. And in the end mqueue never get's really used in the ipc_port_set_seqno(). I tried to go around this by using MACH_SLOCKS and just change the sequence number otherwise. But if you think it's a bad idea maybe there's another way.
