Messages in this thread | | | Date | Thu, 2 May 2013 09:45:08 -0700 | Subject | Re: [PATCH] MIPS: Enable interrupts in arch_cpu_idle() | From | Linus Torvalds <> |
| |
On Thu, May 2, 2013 at 7:58 AM, Ralf Baechle <ralf@linux-mips.org> wrote: > > For a while we just used to live with the race condition resulting from > not disabling interrupts in the idle loop. Then c65a5480 fixed this by > checking if we're returning to the WAIT instruction in the idle loop > when returning from an interrupt and iff so, rolling back the > program counter to point to the if (test_thread_flag(TIF_NEED_RESCHED)) > test at the beginning of rollback_r4k_wait.
Umm. That sounds buggy. What if there was an interrupt *between* the two places, not right at the wait instruction?
It seriously sounds like MIPS should do this by enabling interrupts in the *assembly* code immediately preceding the wait instruction. IOW, you'd effectively have the same kind of "sti; halt" kind of sequence that x86 has. Not "enable interrupts" + C compiler puts random instructions here + "wait".
Linus
| |