Re: [PATCH v4] mm: cma: support sysfs

Dmitry Osipenko
2021-03-19T13:46:54Z

19.03.2021 16:39, Dmitry Osipenko пишет:
> 19.03.2021 15:44, Dmitry Osipenko пишет:
> ...
>>> #include <linux/debugfs.h>
>>> +#include <linux/kobject.h>
>>> +
>>> +struct cma_stat {
>>> + spinlock_t lock;
>>> + /* the number of CMA page successful allocations */
>>> + unsigned long nr_pages_succeeded;
>>> + /* the number of CMA page allocation failures */
>>> + unsigned long nr_pages_failed;
>>> + struct kobject kobj;
>>> +};
>>>
>>> struct cma {
>>> unsigned long base_pfn;
>>> @@ -16,6 +26,9 @@ struct cma {
>>> struct debugfs_u32_array dfs_bitmap;
>>> #endif
>>> char name[CMA_MAX_NAME];
>>> +#ifdef CONFIG_CMA_SYSFS
>>> + struct cma_stat *stat;
>>> +#endif
>
> What is the point of allocating stat dynamically?
>
> ...
>>> +void cma_sysfs_alloc_pages_count(struct cma *cma, size_t count)
>>> +{
>>> + spin_lock(&cma->stat->lock);
>>> + cma->stat->nr_pages_succeeded += count;
>>> + spin_unlock(&cma->stat->lock);
>>> +}
>>> +
>>> +void cma_sysfs_fail_pages_count(struct cma *cma, size_t count)
>>> +{
>>> + spin_lock(&cma->stat->lock);
>>> + cma->stat->nr_pages_failed += count;
>>> + spin_unlock(&cma->stat->lock);
>>> +}
>
> You could use atomic increment and then locking isn't needed.
>

Actually, the counter should be u64 in order not to worry about overflow.