From: Ingo Molnar <mingo@elte.hu>
Date: Sun, 6 Jul 2008 12:23:39 +0000 (+0200)
Subject: Merge commit 'v2.6.26-rc9' into cpus4096
X-Git-Tag: v2.6.27-rc1~848^2~21
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=68083e05d72d94f347293d8cc0067050ba904bfa;p=linux-2.6

Merge commit 'v2.6.26-rc9' into cpus4096
---

68083e05d72d94f347293d8cc0067050ba904bfa
diff --cc include/linux/cpumask.h
index 80226e7761,c24875bd9c..47418b1b41
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@@ -351,49 -343,20 +351,53 @@@ static inline void __cpus_fold(cpumask_
  	bitmap_fold(dstp->bits, origp->bits, sz, nbits);
  }
  
 -#if NR_CPUS > 1
 -#define for_each_cpu_mask(cpu, mask)		\
 -	for ((cpu) = first_cpu(mask);		\
 -		(cpu) < NR_CPUS;		\
 -		(cpu) = next_cpu((cpu), (mask)))
 -#else /* NR_CPUS == 1 */
 -#define for_each_cpu_mask(cpu, mask)		\
 +#if NR_CPUS == 1
 +
 +#define nr_cpu_ids		1
 +#define first_cpu(src)		({ (void)(src); 0; })
 +#define next_cpu(n, src)	({ (void)(src); 1; })
 +#define any_online_cpu(mask)	0
 +#define for_each_cpu_mask(cpu, mask)	\
  	for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask)
 -#endif /* NR_CPUS */
 +
 +#else /* NR_CPUS > 1 */
 +
 +extern int nr_cpu_ids;
 +int __first_cpu(const cpumask_t *srcp);
 +int __next_cpu(int n, const cpumask_t *srcp);
 +int __any_online_cpu(const cpumask_t *mask);
 +
 +#define first_cpu(src)		__first_cpu(&(src))
 +#define next_cpu(n, src)	__next_cpu((n), &(src))
 +#define any_online_cpu(mask) __any_online_cpu(&(mask))
 +#define for_each_cpu_mask(cpu, mask)			\
 +	for ((cpu) = -1;				\
 +		(cpu) = next_cpu((cpu), (mask)),	\
 +		(cpu) < NR_CPUS; )
 +#endif
 +
 +#if NR_CPUS <= 64
 +
 +#define next_cpu_nr(n, src)		next_cpu(n, src)
 +#define cpus_weight_nr(cpumask)		cpus_weight(cpumask)
 +#define for_each_cpu_mask_nr(cpu, mask)	for_each_cpu_mask(cpu, mask)
 +
 +#else /* NR_CPUS > 64 */
 +
 +int __next_cpu_nr(int n, const cpumask_t *srcp);
 +#define next_cpu_nr(n, src)	__next_cpu_nr((n), &(src))
 +#define cpus_weight_nr(cpumask)	__cpus_weight(&(cpumask), nr_cpu_ids)
 +#define for_each_cpu_mask_nr(cpu, mask)			\
 +	for ((cpu) = -1;				\
 +		(cpu) = next_cpu_nr((cpu), (mask)),	\
 +		(cpu) < nr_cpu_ids; )
 +
 +#endif /* NR_CPUS > 64 */
  
+ #define next_cpu_nr(n, src)		next_cpu(n, src)
+ #define cpus_weight_nr(cpumask)		cpus_weight(cpumask)
+ #define for_each_cpu_mask_nr(cpu, mask)	for_each_cpu_mask(cpu, mask)
+ 
  /*
   * The following particular system cpumasks and operations manage
   * possible, present and online cpus.  Each of them is a fixed size
diff --cc kernel/rcuclassic.c
index 251358de70,a38895a5b8..adde10388d
--- a/kernel/rcuclassic.c
+++ b/kernel/rcuclassic.c
@@@ -89,10 -89,24 +89,24 @@@ static void force_quiescent_state(struc
  		/*
  		 * Don't send IPI to itself. With irqs disabled,
  		 * rdp->cpu is the current cpu.
+ 		 *
+ 		 * cpu_online_map is updated by the _cpu_down()
+ 		 * using stop_machine_run(). Since we're in irqs disabled
+ 		 * section, stop_machine_run() is not exectuting, hence
+ 		 * the cpu_online_map is stable.
+ 		 *
+ 		 * However,  a cpu might have been offlined _just_ before
+ 		 * we disabled irqs while entering here.
+ 		 * And rcu subsystem might not yet have handled the CPU_DEAD
+ 		 * notification, leading to the offlined cpu's bit
+ 		 * being set in the rcp->cpumask.
+ 		 *
+ 		 * Hence cpumask = (rcp->cpumask & cpu_online_map) to prevent
+ 		 * sending smp_reschedule() to an offlined CPU.
  		 */
- 		cpumask = rcp->cpumask;
+ 		cpus_and(cpumask, rcp->cpumask, cpu_online_map);
  		cpu_clear(rdp->cpu, cpumask);
 -		for_each_cpu_mask(cpu, cpumask)
 +		for_each_cpu_mask_nr(cpu, cpumask)
  			smp_send_reschedule(cpu);
  	}
  }