user/sven/linux.git/include/linux/rcutiny.h, branch v3.15.3

rcu: Provide grace-period piggybacking API

2014-03-21T00:12:25Z

The following pattern is currently not well supported by RCU: 1. Make data element inaccessible to RCU readers. 2. Do work that probably lasts for more than one grace period. 3. Do something to make sure RCU readers in flight before #1 above have completed. Here are some things that could currently be done: a. Do a synchronize_rcu() unconditionally at either #1 or #3 above. This works, but imposes needless work and latency. b. Post an RCU callback at #1 above that does a wakeup, then wait for the wakeup at #3. This works well, but likely results in an extra unneeded grace period. Open-coding this is also a bit more semi-tricky code than would be good. This commit therefore adds get_state_synchronize_rcu() and cond_synchronize_rcu() APIs. Call get_state_synchronize_rcu() at #1 above and pass its return value to cond_synchronize_rcu() at #3 above. This results in a call to synchronize_rcu() if no grace period has elapsed between #1 and #3, but requires only a load, comparison, and memory barrier if a full grace period did elapse. Requested-by: Peter Zijlstra Signed-off-by: Paul E. McKenney Acked-by: Peter Zijlstra

Merge branches 'doc.2014.02.24a', 'fixes.2014.02.26a' and 'rt.2014.02.17b' into HEAD

2014-02-26T14:36:09Z

doc.2014.02.24a: Documentation changes fixes.2014.02.26a: Miscellaneous fixes rt.2014.02.17b: Response-time-related changes

rcu: Optimize rcu_needs_cpu() for RCU_NOCB_CPU_ALL

2014-02-18T00:03:09Z

If CONFIG_RCU_NOCB_CPU_ALL=y, then rcu_needs_cpu() will always return false, however, the current version nevertheless checks for RCU callbacks. This commit therefore creates a static inline implementation of rcu_needs_cpu() that unconditionally returns false when CONFIG_RCU_NOCB_CPU_ALL=y. Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett

rcu: Stop tracking FSF's postal address

2014-02-17T23:01:37Z

All of the RCU source files have the usual GPL header, which contains a long-obsolete postal address for FSF. To avoid the need to track the FSF office's movements, this commit substitutes the URL where GPL may be found. Reported-by: Greg KH Reported-by: Steven Rostedt Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett

rcu: Remove "extern" from function declarations in include/linux/rcu.h

2013-12-12T20:34:16Z

Function prototypes don't need to have the "extern" keyword since this is the default behavior. Its explicit use is redundant. This commit therefore removes them. Signed-off-by: Teodora Baluta Signed-off-by: Paul E. McKenney

rcu: Consistent rcu_is_watching() naming

2013-09-25T13:45:06Z

The old rcu_is_cpu_idle() function is just __rcu_is_watching() with preemption disabled. This commit therefore renames rcu_is_cpu_idle() to rcu_is_watching. Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett

rcu: Is it safe to enter an RCU read-side critical section?

2013-09-25T13:44:41Z

There is currently no way for kernel code to determine whether it is safe to enter an RCU read-side critical section, in other words, whether or not RCU is paying attention to the currently running CPU. Given the large and increasing quantity of code shared by the idle loop and non-idle code, the this shortcoming is becoming increasingly painful. This commit therefore adds __rcu_is_watching(), which returns true if it is safe to enter an RCU read-side critical section on the currently running CPU. This function is quite fast, using only a __this_cpu_read(). However, the caller must disable preemption. Reported-by: Steven Rostedt Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett

rcu: Shrink TINY_RCU by moving exit_rcu()

2013-06-10T20:45:52Z

Now that TINY_PREEMPT_RCU is no more, exit_rcu() is always an empty function. But if TINY_RCU is going to have an empty function, it should be in include/linux/rcutiny.h, where it does not bloat the kernel. This commit therefore moves exit_rcu() out of kernel/rcupdate.c to kernel/rcutree_plugin.h, and places a static inline empty function in include/linux/rcutiny.h in order to shrink TINY_RCU a bit. Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett

rcu: Remove rcu_preempt_note_context_switch()

2013-06-10T20:45:52Z

With the removal of CONFIG_TINY_PREEMPT_RCU, rcu_preempt_note_context_switch() is now an empty function. This commit therefore eliminates it by inlining it. Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett

rcu: Remove the CONFIG_TINY_RCU ifdefs in rcutiny.h

2013-06-10T20:45:51Z

Now that CONFIG_TINY_PREEMPT_RCU is no more, this commit removes the CONFIG_TINY_RCU ifdefs from include/linux/rcutiny.h in favor of unconditionally compiling the CONFIG_TINY_RCU legs of those ifdefs. Signed-off-by: Paul E. McKenney [ paulmck: Moved removal of #else to "Remove TINY_PREEMPT_RCU" as suggested by Josh Triplett. ] Reviewed-by: Josh Triplett

user/sven/linux.git/include/linux/rcutiny.h, branch v3.15.3

rcu: Provide grace-period piggybacking API

Merge branches 'doc.2014.02.24a', 'fixes.2014.02.26a' and 'rt.2014.02.17b' into HEAD

rcu: Optimize rcu_needs_cpu() for RCU_NOCB_CPU_ALL

rcu: Stop tracking FSF's postal address

rcu: Remove "extern" from function declarations in include/linux/*rcu*.h

rcu: Consistent rcu_is_watching() naming

rcu: Is it safe to enter an RCU read-side critical section?

rcu: Shrink TINY_RCU by moving exit_rcu()

rcu: Remove rcu_preempt_note_context_switch()

rcu: Remove the CONFIG_TINY_RCU ifdefs in rcutiny.h

rcu: Remove "extern" from function declarations in include/linux/rcu.h