On Wed, 7 Jan 2009 22:32:22 +0100 Ingo Molnar <mingo@xxxxxxx> wrote: > > We could do the whole "oldfs = get_fs(); set_fs(KERNEL_DS); .. > > set_fs(oldfs);" crud, but it would probably be better to just add an > > architected accessor. Especially since it's going to generally just be a > > > > #define get_kernel_careful(val,p) __get_user(val,p) > > > > for most architectures. > > > > We've needed that before (and yes, we've simply mis-used __get_user() on > > x86 before rather than add it). > > for the oldfs stuff we already have probe_kernel_read(). OTOH, that > involves pagefault_disable() which is an atomic op tisn't. pagefault_disable() is just preempt_count()+=1;barrier() ? Am suspecting that you guys might be over-optimising this contended-path-were-going-to-spin-anyway code? -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
