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-rw-r--r--include/linux/workqueue.h5
-rw-r--r--kernel/workqueue.c60
2 files changed, 59 insertions, 6 deletions
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index d60c570..b90958a 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -26,6 +26,9 @@ enum {
WORK_STRUCT_PENDING_BIT = 0, /* work item is pending execution */
#ifdef CONFIG_DEBUG_OBJECTS_WORK
WORK_STRUCT_STATIC_BIT = 1, /* static initializer (debugobjects) */
+ WORK_STRUCT_FLAG_BITS = 2,
+#else
+ WORK_STRUCT_FLAG_BITS = 1,
#endif
WORK_STRUCT_PENDING = 1 << WORK_STRUCT_PENDING_BIT,
@@ -35,7 +38,7 @@ enum {
WORK_STRUCT_STATIC = 0,
#endif
- WORK_STRUCT_FLAG_MASK = 3UL,
+ WORK_STRUCT_FLAG_MASK = (1UL << WORK_STRUCT_FLAG_BITS) - 1,
WORK_STRUCT_WQ_DATA_MASK = ~WORK_STRUCT_FLAG_MASK,
};
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index dc78956..74a3849 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -46,7 +46,9 @@
/*
* The per-CPU workqueue (if single thread, we always use the first
- * possible cpu).
+ * possible cpu). The lower WORK_STRUCT_FLAG_BITS of
+ * work_struct->data are used for flags and thus cwqs need to be
+ * aligned at two's power of the number of flag bits.
*/
struct cpu_workqueue_struct {
@@ -59,7 +61,7 @@ struct cpu_workqueue_struct {
struct workqueue_struct *wq; /* I: the owning workqueue */
struct task_struct *thread;
-} ____cacheline_aligned;
+};
/*
* The externally visible workqueue abstraction is an array of
@@ -967,6 +969,53 @@ int current_is_keventd(void)
}
+static struct cpu_workqueue_struct *alloc_cwqs(void)
+{
+ /*
+ * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS.
+ * Make sure that the alignment isn't lower than that of
+ * unsigned long long.
+ */
+ const size_t size = sizeof(struct cpu_workqueue_struct);
+ const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS,
+ __alignof__(unsigned long long));
+ struct cpu_workqueue_struct *cwqs;
+#ifndef CONFIG_SMP
+ void *ptr;
+
+ /*
+ * On UP, percpu allocator doesn't honor alignment parameter
+ * and simply uses arch-dependent default. Allocate enough
+ * room to align cwq and put an extra pointer at the end
+ * pointing back to the originally allocated pointer which
+ * will be used for free.
+ *
+ * FIXME: This really belongs to UP percpu code. Update UP
+ * percpu code to honor alignment and remove this ugliness.
+ */
+ ptr = __alloc_percpu(size + align + sizeof(void *), 1);
+ cwqs = PTR_ALIGN(ptr, align);
+ *(void **)per_cpu_ptr(cwqs + 1, 0) = ptr;
+#else
+ /* On SMP, percpu allocator can do it itself */
+ cwqs = __alloc_percpu(size, align);
+#endif
+ /* just in case, make sure it's actually aligned */
+ BUG_ON(!IS_ALIGNED((unsigned long)cwqs, align));
+ return cwqs;
+}
+
+static void free_cwqs(struct cpu_workqueue_struct *cwqs)
+{
+#ifndef CONFIG_SMP
+ /* on UP, the pointer to free is stored right after the cwq */
+ if (cwqs)
+ free_percpu(*(void **)per_cpu_ptr(cwqs + 1, 0));
+#else
+ free_percpu(cwqs);
+#endif
+}
+
static int create_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu)
{
struct workqueue_struct *wq = cwq->wq;
@@ -1012,7 +1061,7 @@ struct workqueue_struct *__create_workqueue_key(const char *name,
if (!wq)
goto err;
- wq->cpu_wq = alloc_percpu(struct cpu_workqueue_struct);
+ wq->cpu_wq = alloc_cwqs();
if (!wq->cpu_wq)
goto err;
@@ -1031,6 +1080,7 @@ struct workqueue_struct *__create_workqueue_key(const char *name,
for_each_possible_cpu(cpu) {
struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
+ BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK);
cwq->wq = wq;
cwq->cpu = cpu;
spin_lock_init(&cwq->lock);
@@ -1059,7 +1109,7 @@ struct workqueue_struct *__create_workqueue_key(const char *name,
return wq;
err:
if (wq) {
- free_percpu(wq->cpu_wq);
+ free_cwqs(wq->cpu_wq);
kfree(wq);
}
return NULL;
@@ -1112,7 +1162,7 @@ void destroy_workqueue(struct workqueue_struct *wq)
for_each_possible_cpu(cpu)
cleanup_workqueue_thread(get_cwq(cpu, wq));
- free_percpu(wq->cpu_wq);
+ free_cwqs(wq->cpu_wq);
kfree(wq);
}
EXPORT_SYMBOL_GPL(destroy_workqueue);