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authorChristoph Lameter <cl@linux.com>2014-08-27 04:12:21 +0400
committerTejun Heo <tj@kernel.org>2014-08-28 16:58:57 +0400
commit4ba2968420fa9d0604b6a6a5c61bfa8d0fa84ae0 (patch)
treea1051b2a4a23ae8f943f3ae97c0adf6b594e2df0 /include/linux/cpumask.h
parent23f66e2d661b4d3226d16e25910a9e9472ce2410 (diff)
downloadlinux-4ba2968420fa9d0604b6a6a5c61bfa8d0fa84ae0.tar.xz
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: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'include/linux/cpumask.h')
-rw-r--r--include/linux/cpumask.h11
1 files changed, 11 insertions, 0 deletions
diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index 2997af6d2ccd..0a9a6da21e74 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -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;