From: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Date: Tue, 23 Oct 2012 22:12:39 +0000 (-0700)
Subject: Merge branches 'doc.2012.10.23c', 'fixes.2012.10.23c', 'hotplug.2012.10.23c', 'srcu... 
X-Git-Tag: next-20121024~29^2~2
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=38be7d35ad5d465b8f5fb8aa63274f50fb3f2d14;p=karo-tx-linux.git

Merge branches 'doc.2012.10.23c', 'fixes.2012.10.23c', 'hotplug.2012.10.23c', 'srcu.2012.10.23c' and 'stall.2012.10.23c' into dev.3.8.2012.10.23d
---

38be7d35ad5d465b8f5fb8aa63274f50fb3f2d14
diff --cc kernel/rcutree.c
index 74df86bd9204,ca3221595ed5,4eafb89bd60f,74df86bd9204,8ef81527a89f..027153cfa1f4
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@@@@@ -212,20 -212,20 -212,20 -212,20 -212,14 +212,14 @@@@@@ DEFINE_PER_CPU(struct rcu_dynticks, rcu
     #endif
     };
     
- ---static int blimit = 10;		/* Maximum callbacks per rcu_do_batch. */
- ---static int qhimark = 10000;	/* If this many pending, ignore blimit. */
- ---static int qlowmark = 100;	/* Once only this many pending, use blimit. */
+ +++static long blimit = 10;	/* Maximum callbacks per rcu_do_batch. */
+ +++static long qhimark = 10000;	/* If this many pending, ignore blimit. */
+ +++static long qlowmark = 100;	/* Once only this many pending, use blimit. */
     
- ---module_param(blimit, int, 0444);
- ---module_param(qhimark, int, 0444);
- ---module_param(qlowmark, int, 0444);
- -- 
- -- int rcu_cpu_stall_suppress __read_mostly; /* 1 = suppress stall warnings. */
- -- int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT;
- -- 
- -- module_param(rcu_cpu_stall_suppress, int, 0644);
- -- module_param(rcu_cpu_stall_timeout, int, 0644);
+ +++module_param(blimit, long, 0444);
+ +++module_param(qhimark, long, 0444);
+ +++module_param(qlowmark, long, 0444);
     
 -   int rcu_cpu_stall_suppress __read_mostly; /* 1 = suppress stall warnings. */
 -   int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT;
 -   
 -   module_param(rcu_cpu_stall_suppress, int, 0644);
 -   module_param(rcu_cpu_stall_timeout, int, 0644);
 -   
     static ulong jiffies_till_first_fqs = RCU_JIFFIES_TILL_FORCE_QS;
     static ulong jiffies_till_next_fqs = RCU_JIFFIES_TILL_FORCE_QS;
     
@@@@@@ -2308,10 -2347,10 -2305,32 -2308,10 -2301,10 +2337,32 @@@@@@ static int synchronize_sched_expedited_
      */
     void synchronize_sched_expedited(void)
     {
-- --	int firstsnap, s, snap, trycount = 0;
++ ++	long firstsnap, s, snap;
++ ++	int trycount = 0;
++ ++	struct rcu_state *rsp = &rcu_sched_state;
+  + 
 -  -	/* Note that atomic_inc_return() implies full memory barrier. */
 -  -	firstsnap = snap = atomic_inc_return(&sync_sched_expedited_started);
++ ++	/*
++ ++	 * If we are in danger of counter wrap, just do synchronize_sched().
++ ++	 * By allowing sync_sched_expedited_started to advance no more than
++ ++	 * ULONG_MAX/8 ahead of sync_sched_expedited_done, we are ensuring
++ ++	 * that more than 3.5 billion CPUs would be required to force a
++ ++	 * counter wrap on a 32-bit system.  Quite a few more CPUs would of
++ ++	 * course be required on a 64-bit system.
++ ++	 */
++ ++	if (ULONG_CMP_GE((ulong)atomic_long_read(&rsp->expedited_start),
++ ++		         (ulong)atomic_long_read(&rsp->expedited_done) +
++ ++			 ULONG_MAX / 8)) {
++ ++		synchronize_sched();
++ ++		atomic_long_inc(&rsp->expedited_wrap);
++ ++		return;
++ ++	}
 +  +
-  - 	/* Note that atomic_inc_return() implies full memory barrier. */
-  - 	firstsnap = snap = atomic_inc_return(&sync_sched_expedited_started);
++ ++	/*
++ ++	 * Take a ticket.  Note that atomic_inc_return() implies a
++ ++	 * full memory barrier.
++ ++	 */
++ ++	snap = atomic_long_inc_return(&rsp->expedited_start);
++ ++	firstsnap = snap;
     	get_online_cpus();
     	WARN_ON_ONCE(cpu_is_offline(raw_smp_processor_id()));