From: Paul E. McKenney Date: Wed, 20 Apr 2016 16:22:15 +0000 (-0700) Subject: rcu: Document RCU_NONIDLE() restrictions in comment header X-Git-Tag: v4.8-rc1~188^2^2^2~6 X-Git-Url: http://git.cascardo.info/?p=cascardo%2Flinux.git;a=commitdiff_plain;h=810ce8b5df1c8338065f2ae1d2ec08cc566fbb8b rcu: Document RCU_NONIDLE() restrictions in comment header Signed-off-by: Paul E. McKenney --- diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 5f1533e3d032..c61b6b9506e7 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -379,12 +379,13 @@ static inline void rcu_init_nohz(void) * in the inner idle loop. * * This macro provides the way out: RCU_NONIDLE(do_something_with_RCU()) - * will tell RCU that it needs to pay attending, invoke its argument - * (in this example, a call to the do_something_with_RCU() function), + * will tell RCU that it needs to pay attention, invoke its argument + * (in this example, calling the do_something_with_RCU() function), * and then tell RCU to go back to ignoring this CPU. It is permissible - * to nest RCU_NONIDLE() wrappers, but the nesting level is currently - * quite limited. If deeper nesting is required, it will be necessary - * to adjust DYNTICK_TASK_NESTING_VALUE accordingly. + * to nest RCU_NONIDLE() wrappers, but not indefinitely (but the limit is + * on the order of a million or so, even on 32-bit systems). It is + * not legal to block within RCU_NONIDLE(), nor is it permissible to + * transfer control either into or out of RCU_NONIDLE()'s statement. */ #define RCU_NONIDLE(a) \ do { \