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Tue, 23 Mar 2021 20:27:26 -0700 (PDT) Received: from google.com ([2620:15c:211:201:7dfa:1e53:536:7976]) by smtp.gmail.com with ESMTPSA id a144sm555787pfd.200.2021.03.23.20.27.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 23 Mar 2021 20:27:25 -0700 (PDT) Date: Tue, 23 Mar 2021 20:27:23 -0700 From: Minchan Kim To: John Hubbard Cc: Andrew Morton , linux-mm , LKML , gregkh@linuxfoundation.org, surenb@google.com, joaodias@google.com, willy@infradead.org, digetx@gmail.com Subject: Re: [PATCH v6] mm: cma: support sysfs Message-ID: References: <20210324010547.4134370-1-minchan@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 0224B80192D8 X-Stat-Signature: z6nmphpmzs5tw3rsa113p739mim7r1zp Received-SPF: none (gmail.com>: No applicable sender policy available) receiver=imf08; identity=mailfrom; envelope-from=""; helo=mail-pj1-f49.google.com; client-ip=209.85.216.49 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1616556446-951752 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Mar 23, 2021 at 07:34:12PM -0700, John Hubbard wrote: > On 3/23/21 6:05 PM, Minchan Kim wrote: > ...> diff --git a/mm/cma_sysfs.c b/mm/cma_sysfs.c > > new file mode 100644 > > index 000000000000..c3791a032dc5 > > --- /dev/null > > +++ b/mm/cma_sysfs.c > > @@ -0,0 +1,107 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +/* > > + * CMA SysFS Interface > > + * > > + * Copyright (c) 2021 Minchan Kim > > + */ > > + > > +#include > > +#include > > +#include > > + > > +#include "cma.h" > > + > > +void cma_sysfs_account_success_pages(struct cma *cma, size_t count) > > +{ > > + atomic64_add(count, &cma->nr_pages_succeeded); > > +} > > + > > +void cma_sysfs_account_fail_pages(struct cma *cma, size_t count) > > +{ > > + atomic64_add(count, &cma->nr_pages_failed); > > +} > > + > > +#define CMA_ATTR_RO(_name) \ > > + static struct kobj_attribute _name##_attr = __ATTR_RO(_name) > > + > > +#define to_cma_kobject(x) container_of(x, struct cma_kobject, kobj) > > I really don't think that helps. container_of() is so widely used and > understood that it is not a good move make people read one more wrapper > for it. Instead, see below... > > > + > > +static ssize_t alloc_pages_success_show(struct kobject *kobj, > > + struct kobj_attribute *attr, char *buf) > > +{ > > + struct cma_kobject *cma_kobj = to_cma_kobject(kobj); > > + struct cma *cma = cma_kobj->cma; > > ...if you're looking to get rid of the real code duplication, then you > could put *both* of those lines into a wrapper function, instead, like this: > > static inline struct cma* cma_from_kobj(struct kobject *kobj) > { > struct cma_kobject *cma_kobj = container_of(kobj, struct cma_kobject, > kobj); > struct cma *cma = cma_kobj->cma; > > return cma; > } > > static ssize_t alloc_pages_success_show(struct kobject *kobj, > struct kobj_attribute *attr, char *buf) > { > struct cma *cma = cma_from_kobj(kobj); > > return sysfs_emit(buf, "%llu\n", > atomic64_read(&cma->nr_pages_succeeded)); > } > CMA_ATTR_RO(alloc_pages_success); > > static ssize_t alloc_pages_fail_show(struct kobject *kobj, > struct kobj_attribute *attr, char *buf) > { > struct cma *cma = cma_from_kobj(kobj); > > return sysfs_emit(buf, "%llu\n", atomic64_read(&cma->nr_pages_failed)); > } > CMA_ATTR_RO(alloc_pages_fail); > > static void cma_kobj_release(struct kobject *kobj) > { > struct cma_kobject *cma_kobj = container_of(kobj, struct cma_kobject, > kobj); > struct cma *cma = cma_kobj->cma; > > kfree(cma_kobj); > cma->kobj = NULL; > } > > ...isn't that nicer? Saves a little code, gets rid of a macro. Yub. > > > + > > + return sysfs_emit(buf, "%llu\n", > > + atomic64_read(&cma->nr_pages_succeeded)); > > +} > > +CMA_ATTR_RO(alloc_pages_success); > > + > > +static ssize_t alloc_pages_fail_show(struct kobject *kobj, > > + struct kobj_attribute *attr, char *buf) > > +{ > > + struct cma_kobject *cma_kobj = to_cma_kobject(kobj); > > + struct cma *cma = cma_kobj->cma; > > + > > + return sysfs_emit(buf, "%llu\n", atomic64_read(&cma->nr_pages_failed)); > > +} > > +CMA_ATTR_RO(alloc_pages_fail); > > + > > +static void cma_kobj_release(struct kobject *kobj) > > +{ > > + struct cma_kobject *cma_kobj = to_cma_kobject(kobj); > > + struct cma *cma = cma_kobj->cma; > > + > > + kfree(cma_kobj); > > + cma->kobj = NULL; > > +} > > + > > +static struct attribute *cma_attrs[] = { > > + &alloc_pages_success_attr.attr, > > + &alloc_pages_fail_attr.attr, > > + NULL, > > +}; > > +ATTRIBUTE_GROUPS(cma); > > + > > +static struct kobject *cma_kobj_root; > > + > > +static struct kobj_type cma_ktype = { > > + .release = cma_kobj_release, > > + .sysfs_ops = &kobj_sysfs_ops, > > + .default_groups = cma_groups > > +}; > > + > > +static int __init cma_sysfs_init(void) > > +{ > > + unsigned int i; > > + > > + cma_kobj_root = kobject_create_and_add("cma", mm_kobj); > > + if (!cma_kobj_root) > > + return -ENOMEM; > > + > > + for (i = 0; i < cma_area_count; i++) { > > + int err; > > + struct cma *cma; > > + struct cma_kobject *cma_kobj; > > + > > + cma_kobj = kzalloc(sizeof(*cma_kobj), GFP_KERNEL); > > + if (!cma_kobj) { > > + kobject_put(cma_kobj_root); > > + return -ENOMEM; > > This leaks little cma_kobj's all over the floor. :) I thought kobject_put(cma_kobj_root) should deal with it. No? > > What you might want here is a separate routine to clean up, because > it has to loop through and free whatever was allocated on previous > iterations of this loop here. > > > + } > > + > > + cma = &cma_areas[i]; > > + cma->kobj = cma_kobj; > > + cma_kobj->cma = cma; > > + err = kobject_init_and_add(&cma_kobj->kobj, &cma_ktype, > > + cma_kobj_root, "%s", cma->name); > > + if (err) { > > + kobject_put(&cma_kobj->kobj); > > + kobject_put(cma_kobj_root); > > + return err; > > Hopefully this little bit of logic could also go into the cleanup > routine. > > > + } > > + } > > + > > + return 0; > > +} > > +subsys_initcall(cma_sysfs_init); > > > > thanks, > -- > John Hubbard > NVIDIA