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[109.252.193.52]) by smtp.googlemail.com with ESMTPSA id m22sm640702lfa.170.2021.03.19.06.45.57 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 19 Mar 2021 06:45:57 -0700 (PDT) Subject: Re: [PATCH v4] mm: cma: support sysfs From: Dmitry Osipenko To: Minchan Kim , Andrew Morton Cc: linux-mm , LKML , joaodias@google.com, willy@infradead.org, david@redhat.com, surenb@google.com, Greg Kroah-Hartman , John Hubbard , Nicolas Chauvet , "linux-tegra@vger.kernel.org" References: <20210309062333.3216138-1-minchan@kernel.org> Message-ID: <8d7ae527-e0ff-6fa9-7ba3-899a75abc3fa@gmail.com> Date: Fri, 19 Mar 2021 16:45:57 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 19.03.2021 16:39, Dmitry Osipenko пишет: > 19.03.2021 15:44, Dmitry Osipenko пишет: > ... >>> #include >>> +#include >>> + >>> +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.