On Mon, 2007-03-12 at 12:50 +0000, my linux wrote: > > > > > > #ifdef CONFIG_SMP > > lock_kernel(); > > #endif > > > > #ifdef CONFIG_PREEMPT > > preempt_disable(); > > #endif > > > > Is equivalant to > > > > lock_kernel(); > > preempt_disable(); > > > > in UP/SMP and preempt/non-preempt configuration ? > > no, in fact your ifdefs are really incorrect. > the kernel makes those things no-ops IF THEY ARE. But your > lock_kernel() > ifdef for example is really wrong if preempt is enabled! > > CMIIW, when preempt is enabled , lock_kernel() will disable preempt. but not if you wrap it inside CONFIG_SMP !!! (and CONFIG_SMP is off) > > Also could you please elaborate little more on what is "wrong" with > the ifdefs. Since I started working on linux few weeks back. :( they're both ugly and dangerous ugly because they clutter the code dangerous because you introduce bugs (see your own examples above) -- if you want to mail me at work (you don't), use arjan (at) linux.intel.com Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
