On Fri, 16 Aug 2013, Nicholas A. Bellinger wrote:
+ spinlock_t lock;
Remove the spinlock.
+ unsignednr_free;
+ unsignedfreelist[];
+};
+
+static inline void move_tags(unsigned *dst, unsigned *dst_nr,
+ unsigned *src, unsigned *src_nr,
+ unsigned nr)
+{
+ *src_nr -= nr;
+ memcpy(dst + *dst_nr, src + *src_nr, sizeof(unsigned) * nr);
+ *dst_nr += nr;
+}
+
+static inline unsigned alloc_local_tag(struct percpu_ida *pool,
+struct percpu_ida_cpu *tags)
Pass the __percpu offset and not the tags pointer.
+{
+ int tag = -ENOSPC;
+
+ spin_lock(tags-lock);
Interupts are already disabled. Drop the spinlock.
+ if (tags-nr_free)
+ tag = tags-freelist[--tags-nr_free];
You can keep this or avoid address calculation through segment prefixes.
F.e.
if (__this_cpu_read(tags-nrfree) {
int n = __this_cpu_dec_return(tags-nr_free);
tag = __this_cpu_read(tags-freelist[n]);
}
+ spin_unlock(tags-lock);
Drop.
+ * Returns a tag - an integer in the range [0..nr_tags) (passed to
+ * tag_pool_init()), or otherwise -ENOSPC on allocation failure.
+ *
+ * Safe to be called from interrupt context (assuming it isn't passed
+ * __GFP_WAIT, of course).
+ *
+ * Will not fail if passed __GFP_WAIT.
+ */
+int percpu_ida_alloc(struct percpu_ida *pool, gfp_t gfp)
+{
+ DEFINE_WAIT(wait);
+ struct percpu_ida_cpu *tags;
+ unsigned long flags;
+ int tag;
+
+ local_irq_save(flags);
+ tags = this_cpu_ptr(pool-tag_cpu);
You could drop this_cpu_ptr if you pass pool-tag_cpu to alloc_local_tag.
+/**
+ * percpu_ida_free - free a tag
+ * @pool: pool @tag was allocated from
+ * @tag: a tag previously allocated with percpu_ida_alloc()
+ *
+ * Safe to be called from interrupt context.
+ */
+void percpu_ida_free(struct percpu_ida *pool, unsigned tag)
+{
+ struct percpu_ida_cpu *tags;
+ unsigned long flags;
+ unsigned nr_free;
+
+ BUG_ON(tag = pool-nr_tags);
+
+ local_irq_save(flags);
+ tags = this_cpu_ptr(pool-tag_cpu);
+
+ spin_lock(tags-lock);
No need for spinlocking
+ tags-freelist[tags-nr_free++] = tag;
nr_free = __this_cpu_inc_return(pool-tag_cpu.nr_free) ?
__this_cpu_write(pool-tag_cpu.freelist[nr_free], tag)
___
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