diff options
Diffstat (limited to 'include/linux/rcupdate.h')
| -rw-r--r-- | include/linux/rcupdate.h | 23 |
1 files changed, 17 insertions, 6 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 5f1533e3d032..3bc5de08c0b7 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -45,6 +45,7 @@ #include <linux/bug.h> #include <linux/compiler.h> #include <linux/ktime.h> +#include <linux/irqflags.h> #include <asm/barrier.h> @@ -379,12 +380,13 @@ 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 { \ @@ -649,7 +651,16 @@ static inline void rcu_preempt_sleep_check(void) * please be careful when making changes to rcu_assign_pointer() and the * other macros that it invokes. */ -#define rcu_assign_pointer(p, v) smp_store_release(&p, RCU_INITIALIZER(v)) +#define rcu_assign_pointer(p, v) \ +({ \ + uintptr_t _r_a_p__v = (uintptr_t)(v); \ + \ + if (__builtin_constant_p(v) && (_r_a_p__v) == (uintptr_t)NULL) \ + WRITE_ONCE((p), (typeof(p))(_r_a_p__v)); \ + else \ + smp_store_release(&p, RCU_INITIALIZER((typeof(p))_r_a_p__v)); \ + _r_a_p__v; \ +}) /** * rcu_access_pointer() - fetch RCU pointer with no dereferencing |