>>>>> On Mon, 4 Oct 2004 17:00:02 -0700, Jun Sun <jsun@xxxxxxxxxx> said: >> It lacks some preempt_disable/preempt_enable which were in >> preempt-patch for 2.4 kernel. Are these all unnecessary at all? jsun> They are necessary. >> For example, fpu-emulation is not preemptive-safe, isn't it? jsun> That is correct. jsun> I think the best thing to do right now is to go through 2.4 jsun> preemption patch and pick up the missing ones for 2.6. Thank you. I think there are some issue to fix. 1. ll/sc emulation (ll_bit, ll_task). This is easy to fix. 2. There is an global variable ieee754_csr in math-emu. This must be protected by preempt_disable. But math-emu uses put_user/get_user which can not be used with preempt disabled. (Is it true?) 3. save_fp_context/restore_fp_context is not preemptable. But these function uses put_user/get_user. Actually, math-emu/fp_context issues are not only for preemptive kernel. I suppose bad things can happen if a process going to sleep on get_user/put_user in math-emu/save_fp_context/restore_fp_context... --- Atsushi Nemoto
