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Commit 4ba29684 authored by Christoph Lameter's avatar Christoph Lameter Committed by Tejun Heo
Browse files

percpu: Resolve ambiguities in __get_cpu_var/cpumask_var_t 



__get_cpu_var can paper over differences in the definitions of
cpumask_var_t and either use the address of the cpumask variable
directly or perform a fetch of the address of the struct cpumask
allocated elsewhere. This is important particularly when using per cpu
cpumask_var_t declarations because in one case we have an offset into
a per cpu area to handle and in the other case we need to fetch a
pointer from the offset.

This patch introduces a new macro

this_cpu_cpumask_var_ptr()

that is defined where cpumask_var_t is defined and performs the proper
actions. All use cases where __get_cpu_var is used with cpumask_var_t
are converted to the use of this_cpu_cpumask_var_ptr().

Signed-off-by: default avatarChristoph Lameter <cl@linux.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 23f66e2d

arch/x86/include/asm/perf_event_p4.h

+1 −1
Original line number Diff line number Diff line
@@ -189,7 +189,7 @@ static inline int p4_ht_thread(int cpu) 
{

#ifdef CONFIG_SMP

	if (smp_num_siblings == 2)

		return cpu != cpumask_first(__get_cpu_var(cpu_sibling_map));

		return cpu != cpumask_first(this_cpu_cpumask_var_ptr(cpu_sibling_map));

#endif

	return 0;

}

arch/x86/kernel/apic/x2apic_cluster.c

+1 −2
Original line number Diff line number Diff line
@@ -42,8 +42,7 @@ __x2apic_send_IPI_mask(const struct cpumask *mask, int vector, int apic_dest) 
	 * We are to modify mask, so we need an own copy

	 * and be sure it's manipulated with irq off.

	 */

	ipi_mask_ptr = __raw_get_cpu_var(ipi_mask);

	cpumask_copy(ipi_mask_ptr, mask);

	ipi_mask_ptr = this_cpu_cpumask_var_ptr(ipi_mask);



	/*

	 * The idea is to send one IPI per cluster.

arch/x86/oprofile/op_model_p4.c

+1 −1
Original line number Diff line number Diff line
@@ -372,7 +372,7 @@ static unsigned int get_stagger(void) 
{

#ifdef CONFIG_SMP

	int cpu = smp_processor_id();

	return cpu != cpumask_first(__get_cpu_var(cpu_sibling_map));

	return cpu != cpumask_first(this_cpu_cpumask_var_ptr(cpu_sibling_map));

#endif

	return 0;

}

include/linux/cpumask.h

+11 −0
Original line number Diff line number Diff line
@@ -666,10 +666,19 @@ static inline size_t cpumask_size(void) 
 *

 * This code makes NR_CPUS length memcopy and brings to a memory corruption.

 * cpumask_copy() provide safe copy functionality.

 *

 * Note that there is another evil here: If you define a cpumask_var_t

 * as a percpu variable then the way to obtain the address of the cpumask

 * structure differently influences what this_cpu_* operation needs to be

 * used. Please use this_cpu_cpumask_var_t in those cases. The direct use

 * of this_cpu_ptr() or this_cpu_read() will lead to failures when the

 * other type of cpumask_var_t implementation is configured.

 */

#ifdef CONFIG_CPUMASK_OFFSTACK

typedef struct cpumask *cpumask_var_t;



#define this_cpu_cpumask_var_ptr(x) this_cpu_read(x)



bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node);

bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags);

bool zalloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node);
@@ -681,6 +690,8 @@ void free_bootmem_cpumask_var(cpumask_var_t mask); 
#else

typedef struct cpumask cpumask_var_t[1];



#define this_cpu_cpumask_var_ptr(x) this_cpu_ptr(x)



static inline bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)

{

	return true;

kernel/sched/deadline.c

+1 −1
Original line number Diff line number Diff line
@@ -1158,7 +1158,7 @@ static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask_dl); 
static int find_later_rq(struct task_struct *task)

{

	struct sched_domain *sd;

	struct cpumask *later_mask = __get_cpu_var(local_cpu_mask_dl);

	struct cpumask *later_mask = this_cpu_cpumask_var_ptr(local_cpu_mask_dl);

	int this_cpu = smp_processor_id();

	int best_cpu, cpu = task_cpu(task);