From patchwork Mon May 4 11:03:41 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Emanuele Giuseppe Esposito X-Patchwork-Id: 1282423 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=kvm-ppc-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=fjfzFCSM; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 49G0PB0PpBz9sTV for ; Mon, 4 May 2020 21:04:46 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728388AbgEDLEn (ORCPT ); Mon, 4 May 2020 07:04:43 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:20840 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728557AbgEDLED (ORCPT ); Mon, 4 May 2020 07:04:03 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588590238; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=fSn3n1+VKSGdJaAakXEFfOuaSKKQn6CmMSoun+hZIb8=; b=fjfzFCSMrOVOo2/VRZxXGhR7ZuUU58ZL4xjH2FzJaU48IftF3BEvwbFriW5gtafocH1bgx jCtK1pRRBVA+9apuo+2q/Guor5Ap+vFuQgAd1DgHFhPuEJ6mUIUd0B5o2zwlAvHp3KbhIe CWog1iauv6nKyXlkIdUC/eDuEo3XhxA= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-289-56QPmZ91OMqQ4P_7QVX4TQ-1; Mon, 04 May 2020 07:03:56 -0400 X-MC-Unique: 56QPmZ91OMqQ4P_7QVX4TQ-1 Received: by mail-wm1-f70.google.com with SMTP id d134so7194777wmd.0 for ; Mon, 04 May 2020 04:03:56 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=fSn3n1+VKSGdJaAakXEFfOuaSKKQn6CmMSoun+hZIb8=; b=K47VveWN6O2kIUN62x//zuGE+hXvCx3Ns17V2MjLL2Nt037fviyrwUIhWveETThvi5 4CCukPLnXqAew1mm9BqgjGPr07NUdhHK5wnROl93SGgEq71DpQVM1+vXvQoOOGzC0eMB wJs9sarQ74/Ytg6o5r8CL2iNCNEEIknPN/KQhnte1HidWx89iNzEV7ogQ5Zu40yOUWmb 0V19n9+GY9bhzn1XMRVHQJvB425jn5CzhufaxcJ2KKGhqjGAuI/v6W2Qpx+bcAOqHjwZ bJMzeUvR8a3RxHdVZTP0egcgF7xX9BIRgM4wJIzQ8OL5wmYfhULqVva5Td3a+KH/ZJID 50lQ== X-Gm-Message-State: AGi0PuZRlpNMVw2Lc8HbSC5f1HRxyDcxXf2dvvJ4S+jsQK8vyWUHHQMd tgskWAbxM0Q82Cbtqol7e9UG0t4nQr2RF+WA8+GdwMkS7f7Hao2pngWUjXFWCBgI1KvfOS9ru5c rdQkIR5BWVM1IlZep6g== X-Received: by 2002:a05:600c:2284:: with SMTP id 4mr13390267wmf.97.1588590235193; Mon, 04 May 2020 04:03:55 -0700 (PDT) X-Google-Smtp-Source: APiQypLJqu3DOrztAyLE6v9HzeLihNpmYDouMJppNQ0dvBekcYyyFI3qXLea1b9RhQ4EcLdqXBNh8g== X-Received: by 2002:a05:600c:2284:: with SMTP id 4mr13390197wmf.97.1588590234420; Mon, 04 May 2020 04:03:54 -0700 (PDT) Received: from localhost.localdomain.com ([194.230.155.213]) by smtp.gmail.com with ESMTPSA id a13sm10885750wrv.67.2020.05.04.04.03.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 04 May 2020 04:03:53 -0700 (PDT) From: Emanuele Giuseppe Esposito To: kvm@vger.kernel.org Cc: Christian Borntraeger , David Hildenbrand , Cornelia Huck , Paolo Bonzini , Vitaly Kuznetsov , Jim Mattson , Alexander Viro , Emanuele Giuseppe Esposito , linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-fsdevel@vger.kernel.org, Emanuele Giuseppe Esposito Subject: [PATCH v2 2/5] stats_fs API: create, add and remove stats_fs sources and values Date: Mon, 4 May 2020 13:03:41 +0200 Message-Id: <20200504110344.17560-3-eesposit@redhat.com> X-Mailer: git-send-email 2.25.2 In-Reply-To: <20200504110344.17560-1-eesposit@redhat.com> References: <20200504110344.17560-1-eesposit@redhat.com> MIME-Version: 1.0 Sender: kvm-ppc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm-ppc@vger.kernel.org Introduction to the stats_fs API, that allows to easily create, add and remove stats_fs sources and values. The API allows to easily building the statistics directory tree to automatically gather them for the linux kernel. The main functionalities are: create a source, add child sources/values/aggregates, register it to the root source (that on the virtual fs would be /sys/kernel/statsfs), ad perform a search for a value/aggregate. This allows creating any kind of source tree, making it more flexible also to future readjustments. The API representation is only logical and will be backed up by a virtual file system in patch 4. Its usage will be shared between the stats_fs file system and the end-users like kvm, the former calling it when it needs to display and clear statistics, the latter to add values and sources. Signed-off-by: Emanuele Giuseppe Esposito --- MAINTAINERS | 7 + fs/Kconfig | 6 + fs/Makefile | 1 + fs/stats_fs/Makefile | 4 + fs/stats_fs/internal.h | 20 ++ fs/stats_fs/stats_fs.c | 610 +++++++++++++++++++++++++++++++++++++++ include/linux/stats_fs.h | 289 +++++++++++++++++++ 7 files changed, 937 insertions(+) create mode 100644 fs/stats_fs/Makefile create mode 100644 fs/stats_fs/internal.h create mode 100644 fs/stats_fs/stats_fs.c create mode 100644 include/linux/stats_fs.h diff --git a/MAINTAINERS b/MAINTAINERS index b816a453b10e..a8403d07cee5 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -5229,6 +5229,13 @@ F: include/linux/debugfs.h F: include/linux/kobj* F: lib/kobj* +STATS_FS +M: Paolo Bonzini +R: Emanuele Giuseppe Esposito +S: Supported +F: include/linux/stats_fs.h +F: fs/stats_fs + DRIVERS FOR ADAPTIVE VOLTAGE SCALING (AVS) M: Kevin Hilman M: Nishanth Menon diff --git a/fs/Kconfig b/fs/Kconfig index f08fbbfafd9a..1b0de0f19e96 100644 --- a/fs/Kconfig +++ b/fs/Kconfig @@ -328,4 +328,10 @@ source "fs/unicode/Kconfig" config IO_WQ bool +config STATS_FS + bool "Statistics Filesystem" + help + stats_fs is a virtual file system that provides counters and + other statistics about the running kernel. + endmenu diff --git a/fs/Makefile b/fs/Makefile index 2ce5112b02c8..91558eca0cf7 100644 --- a/fs/Makefile +++ b/fs/Makefile @@ -125,6 +125,7 @@ obj-$(CONFIG_BEFS_FS) += befs/ obj-$(CONFIG_HOSTFS) += hostfs/ obj-$(CONFIG_CACHEFILES) += cachefiles/ obj-$(CONFIG_DEBUG_FS) += debugfs/ +obj-$(CONFIG_STATS_FS) += stats_fs/ obj-$(CONFIG_TRACING) += tracefs/ obj-$(CONFIG_OCFS2_FS) += ocfs2/ obj-$(CONFIG_BTRFS_FS) += btrfs/ diff --git a/fs/stats_fs/Makefile b/fs/stats_fs/Makefile new file mode 100644 index 000000000000..94fe52d590d5 --- /dev/null +++ b/fs/stats_fs/Makefile @@ -0,0 +1,4 @@ +# SPDX-License-Identifier: GPL-2.0-only +stats_fs-objs := stats_fs.o + +obj-$(CONFIG_STATS_FS) += stats_fs.o diff --git a/fs/stats_fs/internal.h b/fs/stats_fs/internal.h new file mode 100644 index 000000000000..ddf262a60736 --- /dev/null +++ b/fs/stats_fs/internal.h @@ -0,0 +1,20 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _STATS_FS_INTERNAL_H_ +#define _STATS_FS_INTERNAL_H_ + +#include +#include +#include +#include + +/* values, grouped by base */ +struct stats_fs_value_source { + void *base_addr; + bool files_created; + struct stats_fs_value *values; + struct list_head list_element; +}; + +int stats_fs_val_get_mode(struct stats_fs_value *val); + +#endif /* _STATS_FS_INTERNAL_H_ */ diff --git a/fs/stats_fs/stats_fs.c b/fs/stats_fs/stats_fs.c new file mode 100644 index 000000000000..b63de12769e2 --- /dev/null +++ b/fs/stats_fs/stats_fs.c @@ -0,0 +1,610 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "internal.h" + +struct stats_fs_aggregate_value { + uint64_t sum, min, max; + uint32_t count, count_zero; +}; + +static int is_val_signed(struct stats_fs_value *val) +{ + return val->type & STATS_FS_SIGN; +} + +int stats_fs_val_get_mode(struct stats_fs_value *val) +{ + return val->mode ? val->mode : 0644; +} + +static struct stats_fs_value *find_value(struct stats_fs_value_source *src, + struct stats_fs_value *val) +{ + struct stats_fs_value *entry; + + for (entry = src->values; entry->name; entry++) { + if (entry == val) + return entry; + } + return NULL; +} + +static struct stats_fs_value * +search_value_in_source(struct stats_fs_source *src, struct stats_fs_value *arg, + struct stats_fs_value_source **val_src) +{ + struct stats_fs_value *entry; + struct stats_fs_value_source *src_entry; + + list_for_each_entry (src_entry, &src->values_head, list_element) { + entry = find_value(src_entry, arg); + if (entry) { + *val_src = src_entry; + return entry; + } + } + + return NULL; +} + +/* Called with rwsem held for writing */ +static struct stats_fs_value_source *create_value_source(void *base) +{ + struct stats_fs_value_source *val_src; + + val_src = kzalloc(sizeof(struct stats_fs_value_source), GFP_KERNEL); + if (!val_src) + return ERR_PTR(-ENOMEM); + + val_src->base_addr = base; + INIT_LIST_HEAD(&val_src->list_element); + + return val_src; +} + +int stats_fs_source_add_values(struct stats_fs_source *source, + struct stats_fs_value *stat, void *ptr) +{ + struct stats_fs_value_source *val_src; + struct stats_fs_value_source *entry; + + down_write(&source->rwsem); + + list_for_each_entry (entry, &source->values_head, list_element) { + if (entry->base_addr == ptr && entry->values == stat) { + up_write(&source->rwsem); + return -EEXIST; + } + } + + val_src = create_value_source(ptr); + val_src->values = (struct stats_fs_value *)stat; + + /* add the val_src to the source list */ + list_add(&val_src->list_element, &source->values_head); + + up_write(&source->rwsem); + + return 0; +} +EXPORT_SYMBOL_GPL(stats_fs_source_add_values); + +void stats_fs_source_add_subordinate(struct stats_fs_source *source, + struct stats_fs_source *sub) +{ + down_write(&source->rwsem); + + stats_fs_source_get(sub); + list_add(&sub->list_element, &source->subordinates_head); + + up_write(&source->rwsem); +} +EXPORT_SYMBOL_GPL(stats_fs_source_add_subordinate); + +/* Called with rwsem held for writing */ +static void +stats_fs_source_remove_subordinate_locked(struct stats_fs_source *source, + struct stats_fs_source *sub) +{ + struct stats_fs_source *src_entry; + + list_for_each_entry (src_entry, &source->subordinates_head, + list_element) { + if (src_entry == sub) { + list_del_init(&src_entry->list_element); + stats_fs_source_put(src_entry); + return; + } + } +} + +void stats_fs_source_remove_subordinate(struct stats_fs_source *source, + struct stats_fs_source *sub) +{ + down_write(&source->rwsem); + stats_fs_source_remove_subordinate_locked(source, sub); + up_write(&source->rwsem); +} +EXPORT_SYMBOL_GPL(stats_fs_source_remove_subordinate); + +/* Called with rwsem held for reading */ +static uint64_t get_simple_value(struct stats_fs_value_source *src, + struct stats_fs_value *val) +{ + uint64_t value_found; + void *address; + + address = src->base_addr + val->offset; + + switch (val->type) { + case STATS_FS_U8: + value_found = *((uint8_t *)address); + break; + case STATS_FS_U8 | STATS_FS_SIGN: + value_found = *((int8_t *)address); + break; + case STATS_FS_U16: + value_found = *((uint16_t *)address); + break; + case STATS_FS_U16 | STATS_FS_SIGN: + value_found = *((int16_t *)address); + break; + case STATS_FS_U32: + value_found = *((uint32_t *)address); + break; + case STATS_FS_U32 | STATS_FS_SIGN: + value_found = *((int32_t *)address); + break; + case STATS_FS_U64: + value_found = *((uint64_t *)address); + break; + case STATS_FS_U64 | STATS_FS_SIGN: + value_found = *((int64_t *)address); + break; + case STATS_FS_BOOL: + value_found = *((uint8_t *)address); + break; + default: + value_found = 0; + break; + } + + return value_found; +} + +/* Called with rwsem held for reading */ +static void clear_simple_value(struct stats_fs_value_source *src, + struct stats_fs_value *val) +{ + void *address; + + address = src->base_addr + val->offset; + + switch (val->type) { + case STATS_FS_U8: + *((uint8_t *)address) = 0; + break; + case STATS_FS_U8 | STATS_FS_SIGN: + *((int8_t *)address) = 0; + break; + case STATS_FS_U16: + *((uint16_t *)address) = 0; + break; + case STATS_FS_U16 | STATS_FS_SIGN: + *((int16_t *)address) = 0; + break; + case STATS_FS_U32: + *((uint32_t *)address) = 0; + break; + case STATS_FS_U32 | STATS_FS_SIGN: + *((int32_t *)address) = 0; + break; + case STATS_FS_U64: + *((uint64_t *)address) = 0; + break; + case STATS_FS_U64 | STATS_FS_SIGN: + *((int64_t *)address) = 0; + break; + case STATS_FS_BOOL: + *((uint8_t *)address) = 0; + break; + default: + break; + } +} + +/* Called with rwsem held for reading */ +static void +search_all_simple_values(struct stats_fs_source *src, + struct stats_fs_value_source *ref_src_entry, + struct stats_fs_value *val, + struct stats_fs_aggregate_value *agg) +{ + struct stats_fs_value_source *src_entry; + uint64_t value_found; + + list_for_each_entry (src_entry, &src->values_head, list_element) { + /* skip aggregates */ + if (src_entry->base_addr == NULL) + continue; + + /* useless to search here */ + if (src_entry->values != ref_src_entry->values) + continue; + + /* must be here */ + value_found = get_simple_value(src_entry, val); + agg->sum += value_found; + agg->count++; + agg->count_zero += (value_found == 0); + + if (is_val_signed(val)) { + agg->max = (((int64_t)value_found) >= + ((int64_t)agg->max)) ? + value_found : + agg->max; + agg->min = (((int64_t)value_found) <= + ((int64_t)agg->min)) ? + value_found : + agg->min; + } else { + agg->max = (value_found >= agg->max) ? value_found : + agg->max; + agg->min = (value_found <= agg->min) ? value_found : + agg->min; + } + } +} + +/* Called with rwsem held for reading */ +static void +do_recursive_aggregation(struct stats_fs_source *root, + struct stats_fs_value_source *ref_src_entry, + struct stats_fs_value *val, + struct stats_fs_aggregate_value *agg) +{ + struct stats_fs_source *subordinate; + + /* search all simple values in this folder */ + search_all_simple_values(root, ref_src_entry, val, agg); + + /* recursively search in all subfolders */ + list_for_each_entry (subordinate, &root->subordinates_head, + list_element) { + down_read(&subordinate->rwsem); + do_recursive_aggregation(subordinate, ref_src_entry, val, agg); + up_read(&subordinate->rwsem); + } +} + +/* Called with rwsem held for reading */ +static void init_aggregate_value(struct stats_fs_aggregate_value *agg, + struct stats_fs_value *val) +{ + agg->count = agg->count_zero = agg->sum = 0; + if (is_val_signed(val)) { + agg->max = S64_MIN; + agg->min = S64_MAX; + } else { + agg->max = 0; + agg->min = U64_MAX; + } +} + +/* Called with rwsem held for reading */ +static void store_final_value(struct stats_fs_aggregate_value *agg, + struct stats_fs_value *val, uint64_t *ret) +{ + int operation; + + operation = val->aggr_kind | is_val_signed(val); + + switch (operation) { + case STATS_FS_AVG: + *ret = agg->count ? agg->sum / agg->count : 0; + break; + case STATS_FS_AVG | STATS_FS_SIGN: + *ret = agg->count ? ((int64_t)agg->sum) / agg->count : 0; + break; + case STATS_FS_SUM: + case STATS_FS_SUM | STATS_FS_SIGN: + *ret = agg->sum; + break; + case STATS_FS_MIN: + case STATS_FS_MIN | STATS_FS_SIGN: + *ret = agg->min; + break; + case STATS_FS_MAX: + case STATS_FS_MAX | STATS_FS_SIGN: + *ret = agg->max; + break; + case STATS_FS_COUNT_ZERO: + case STATS_FS_COUNT_ZERO | STATS_FS_SIGN: + *ret = agg->count_zero; + break; + default: + break; + } +} + +/* Called with rwsem held for reading */ +static int stats_fs_source_get_value_locked(struct stats_fs_source *source, + struct stats_fs_value *arg, + uint64_t *ret) +{ + struct stats_fs_value_source *src_entry; + struct stats_fs_value *found; + struct stats_fs_aggregate_value aggr; + + *ret = 0; + + if (!arg) + return -ENOENT; + + /* look in simple values */ + found = search_value_in_source(source, arg, &src_entry); + + if (!found) { + printk(KERN_ERR "Stats_fs: Value in source \"%s\" not found!\n", + source->name); + return -ENOENT; + } + + if (src_entry->base_addr != NULL) { + *ret = get_simple_value(src_entry, found); + return 0; + } + + /* look in aggregates */ + init_aggregate_value(&aggr, found); + do_recursive_aggregation(source, src_entry, found, &aggr); + store_final_value(&aggr, found, ret); + + return 0; +} + +int stats_fs_source_get_value(struct stats_fs_source *source, + struct stats_fs_value *arg, uint64_t *ret) +{ + int retval; + + down_read(&source->rwsem); + retval = stats_fs_source_get_value_locked(source, arg, ret); + up_read(&source->rwsem); + + return retval; +} +EXPORT_SYMBOL_GPL(stats_fs_source_get_value); + +/* Called with rwsem held for reading */ +static void set_all_simple_values(struct stats_fs_source *src, + struct stats_fs_value_source *ref_src_entry, + struct stats_fs_value *val) +{ + struct stats_fs_value_source *src_entry; + + list_for_each_entry (src_entry, &src->values_head, list_element) { + /* skip aggregates */ + if (src_entry->base_addr == NULL) + continue; + + /* wrong to search here */ + if (src_entry->values != ref_src_entry->values) + continue; + + if (src_entry->base_addr && + src_entry->values == ref_src_entry->values) + clear_simple_value(src_entry, val); + } +} + +/* Called with rwsem held for reading */ +static void do_recursive_clean(struct stats_fs_source *root, + struct stats_fs_value_source *ref_src_entry, + struct stats_fs_value *val) +{ + struct stats_fs_source *subordinate; + + /* search all simple values in this folder */ + set_all_simple_values(root, ref_src_entry, val); + + /* recursively search in all subfolders */ + list_for_each_entry (subordinate, &root->subordinates_head, + list_element) { + down_read(&subordinate->rwsem); + do_recursive_clean(subordinate, ref_src_entry, val); + up_read(&subordinate->rwsem); + } +} + +/* Called with rwsem held for reading */ +static int stats_fs_source_clear_locked(struct stats_fs_source *source, + struct stats_fs_value *val) +{ + struct stats_fs_value_source *src_entry; + struct stats_fs_value *found; + + if (!val) + return -ENOENT; + + /* look in simple values */ + found = search_value_in_source(source, val, &src_entry); + + if (!found) { + printk(KERN_ERR "Stats_fs: Value in source \"%s\" not found!\n", + source->name); + return -ENOENT; + } + + if (src_entry->base_addr != NULL) { + clear_simple_value(src_entry, found); + return 0; + } + + /* look in aggregates */ + do_recursive_clean(source, src_entry, found); + + return 0; +} + +int stats_fs_source_clear(struct stats_fs_source *source, + struct stats_fs_value *val) +{ + int retval; + + down_read(&source->rwsem); + retval = stats_fs_source_clear_locked(source, val); + up_read(&source->rwsem); + + return retval; +} + +/* Called with rwsem held for reading */ +static struct stats_fs_value * +find_value_by_name(struct stats_fs_value_source *src, char *val) +{ + struct stats_fs_value *entry; + + for (entry = src->values; entry->name; entry++) + if (!strcmp(entry->name, val)) + return entry; + + return NULL; +} + +/* Called with rwsem held for reading */ +static struct stats_fs_value * +search_in_source_by_name(struct stats_fs_source *src, char *name) +{ + struct stats_fs_value *entry; + struct stats_fs_value_source *src_entry; + + list_for_each_entry (src_entry, &src->values_head, list_element) { + entry = find_value_by_name(src_entry, name); + if (entry) + return entry; + } + + return NULL; +} + +int stats_fs_source_get_value_by_name(struct stats_fs_source *source, + char *name, uint64_t *ret) +{ + struct stats_fs_value *val; + int retval; + + down_read(&source->rwsem); + val = search_in_source_by_name(source, name); + + if (!val) { + *ret = 0; + up_read(&source->rwsem); + return -ENOENT; + } + + retval = stats_fs_source_get_value_locked(source, val, ret); + up_read(&source->rwsem); + + return retval; +} +EXPORT_SYMBOL_GPL(stats_fs_source_get_value_by_name); + +void stats_fs_source_get(struct stats_fs_source *source) +{ + kref_get(&source->refcount); +} +EXPORT_SYMBOL_GPL(stats_fs_source_get); + +void stats_fs_source_revoke(struct stats_fs_source *source) +{ + struct stats_fs_value_source *val_src_entry; + + down_write(&source->rwsem); + + list_for_each_entry (val_src_entry, &source->values_head, list_element) + val_src_entry->base_addr = NULL; + + up_write(&source->rwsem); +} +EXPORT_SYMBOL_GPL(stats_fs_source_revoke); + +/* Called with rwsem held for writing + * + * The refcount is 0 and the lock was taken before refcount + * went from 1 to 0 + */ +static void stats_fs_source_destroy(struct kref *kref_source) +{ + struct stats_fs_value_source *val_src_entry; + struct list_head *it, *safe; + struct stats_fs_source *child, *source; + + source = container_of(kref_source, struct stats_fs_source, refcount); + + /* iterate through the values and delete them */ + list_for_each_safe (it, safe, &source->values_head) { + val_src_entry = list_entry(it, struct stats_fs_value_source, + list_element); + kfree(val_src_entry); + } + + /* iterate through the subordinates and delete them */ + list_for_each_safe (it, safe, &source->subordinates_head) { + child = list_entry(it, struct stats_fs_source, list_element); + stats_fs_source_remove_subordinate_locked(source, child); + } + + up_write(&source->rwsem); + kfree(source->name); + kfree(source); +} + +void stats_fs_source_put(struct stats_fs_source *source) +{ + kref_put_rwsem(&source->refcount, stats_fs_source_destroy, + &source->rwsem); +} +EXPORT_SYMBOL_GPL(stats_fs_source_put); + +struct stats_fs_source *stats_fs_source_create(const char *fmt, ...) +{ + va_list ap; + char buf[100]; + struct stats_fs_source *ret; + int char_needed; + + va_start(ap, fmt); + char_needed = vsnprintf(buf, 100, fmt, ap); + va_end(ap); + + ret = kzalloc(sizeof(struct stats_fs_source), GFP_KERNEL); + if (!ret) + return ERR_PTR(-ENOMEM); + + ret->name = kstrdup(buf, GFP_KERNEL); + if (!ret->name) { + kfree(ret); + return ERR_PTR(-ENOMEM); + } + + kref_init(&ret->refcount); + init_rwsem(&ret->rwsem); + + INIT_LIST_HEAD(&ret->values_head); + INIT_LIST_HEAD(&ret->subordinates_head); + INIT_LIST_HEAD(&ret->list_element); + + return ret; +} +EXPORT_SYMBOL_GPL(stats_fs_source_create); diff --git a/include/linux/stats_fs.h b/include/linux/stats_fs.h new file mode 100644 index 000000000000..dc2d2e11f5ea --- /dev/null +++ b/include/linux/stats_fs.h @@ -0,0 +1,289 @@ +/* SPDX-License-Identifier: GPL-2.0 + * + * stats_fs.h - a tiny little statistics file system + * + * Copyright (C) 2020 Emanuele Giuseppe Esposito + * Copyright (C) 2020 Redhat. + * + */ + +#ifndef _STATS_FS_H_ +#define _STATS_FS_H_ + +#include + +/* Used to distinguish signed types */ +#define STATS_FS_SIGN 0x8000 + +enum stat_type { + STATS_FS_U8 = 0, + STATS_FS_U16 = 1, + STATS_FS_U32 = 2, + STATS_FS_U64 = 3, + STATS_FS_BOOL = 4, + STATS_FS_S8 = STATS_FS_U8 | STATS_FS_SIGN, + STATS_FS_S16 = STATS_FS_U16 | STATS_FS_SIGN, + STATS_FS_S32 = STATS_FS_U32 | STATS_FS_SIGN, + STATS_FS_S64 = STATS_FS_U64 | STATS_FS_SIGN, +}; + +enum stat_aggr { + STATS_FS_NONE = 0, + STATS_FS_SUM, + STATS_FS_MIN, + STATS_FS_MAX, + STATS_FS_COUNT_ZERO, + STATS_FS_AVG, +}; + +struct stats_fs_value { + /* Name of the stat */ + char *name; + + /* Offset from base address to field containing the value */ + int offset; + + /* Type of the stat BOOL,U64,... */ + enum stat_type type; + + /* Aggregate type: MIN, MAX, SUM,... */ + enum stat_aggr aggr_kind; + + /* File mode */ + uint16_t mode; +}; + +struct stats_fs_source { + struct kref refcount; + + char *name; + + /* list of source stats_fs_value_source*/ + struct list_head values_head; + + /* list of struct stats_fs_source for subordinate sources */ + struct list_head subordinates_head; + + struct list_head list_element; + + struct rw_semaphore rwsem; + + struct dentry *source_dentry; +}; + +#if defined(CONFIG_STATS_FS) + +/** + * stats_fs_source_create - create a stats_fs_source + * Creates a stats_fs_source with the given name. This + * does not mean it will be backed by the filesystem yet, it will only + * be visible to the user once one of its parents (or itself) are + * registered in stats_fs. + * + * Returns a pointer to a stats_fs_source if it succeeds. + * This or one of the parents' pointer must be passed to the stats_fs_put() + * function when the file is to be removed. If an error occurs, + * ERR_PTR(-ERROR) will be returned. + */ +struct stats_fs_source *stats_fs_source_create(const char *fmt, ...); + +/** + * stats_fs_source_add_values - adds values to the given source + * @source: a pointer to the source that will receive the values + * @val: a pointer to the NULL terminated stats_fs_value array to add + * @base_ptr: a pointer to the base pointer used by these values + * + * In addition to adding values to the source, also create the + * files in the filesystem if the source already is backed up by a directory. + * + * Returns 0 it succeeds. If the value are already in the + * source and have the same base_ptr, -EEXIST is returned. + */ +int stats_fs_source_add_values(struct stats_fs_source *source, + struct stats_fs_value *val, void *base_ptr); + +/** + * stats_fs_source_add_subordinate - adds a child to the given source + * @parent: a pointer to the parent source + * @child: a pointer to child source to add + * + * Recursively create all files in the stats_fs filesystem + * only if the parent has already a dentry (created with + * stats_fs_source_register). + * This avoids the case where this function is called before register. + */ +void stats_fs_source_add_subordinate(struct stats_fs_source *parent, + struct stats_fs_source *child); + +/** + * stats_fs_source_remove_subordinate - removes a child from the given source + * @parent: a pointer to the parent source + * @child: a pointer to child source to remove + * + * Look if there is such child in the parent. If so, + * it will remove all its files and call stats_fs_put on the child. + */ +void stats_fs_source_remove_subordinate(struct stats_fs_source *parent, + struct stats_fs_source *child); + +/** + * stats_fs_source_get_value - search a value in the source (and + * subordinates) + * @source: a pointer to the source that will be searched + * @val: a pointer to the stats_fs_value to search + * @ret: a pointer to the uint64_t that will hold the found value + * + * Look up in the source if a value with same value pointer + * exists. + * If not, it will return -ENOENT. If it exists and it's a simple value + * (not an aggregate), the value that it points to will be returned. + * If it exists and it's an aggregate (aggr_type != STATS_FS_NONE), all + * subordinates will be recursively searched and every simple value match + * will be used to aggregate the final result. For example if it's a sum, + * all suboordinates having the same value will be sum together. + * + * This function will return 0 it succeeds. + */ +int stats_fs_source_get_value(struct stats_fs_source *source, + struct stats_fs_value *val, uint64_t *ret); + +/** + * stats_fs_source_get_value_by_name - search a value in the source (and + * subordinates) + * @source: a pointer to the source that will be searched + * @name: a pointer to the string representing the value to search + * (for example "exits") + * @ret: a pointer to the uint64_t that will hold the found value + * + * Same as stats_fs_source_get_value, but initially the name is used + * to search in the given source if there is a value with a matching + * name. If so, stats_fs_source_get_value will be called with the found + * value, otherwise -ENOENT will be returned. + */ +int stats_fs_source_get_value_by_name(struct stats_fs_source *source, + char *name, uint64_t *ret); + +/** + * stats_fs_source_clear - search and clears a value in the source (and + * subordinates) + * @source: a pointer to the source that will be searched + * @val: a pointer to the stats_fs_value to search + * + * Look up in the source if a value with same value pointer + * exists. + * If not, it will return -ENOENT. If it exists and it's a simple value + * (not an aggregate), the value that it points to will be set to 0. + * If it exists and it's an aggregate (aggr_type != STATS_FS_NONE), all + * subordinates will be recursively searched and every simple value match + * will be set to 0. + * + * This function will return 0 it succeeds. + */ +int stats_fs_source_clear(struct stats_fs_source *source, + struct stats_fs_value *val); + +/** + * stats_fs_source_revoke - disconnect the source from its backing data + * @source: a pointer to the source that will be revoked + * + * Ensure that stats_fs will not access the data that were passed to + * stats_fs_source_add_value for this source. + * + * Because open files increase the reference count for a stats_fs_source, + * the source can end up living longer than the data that provides the + * values for the source. Calling stats_fs_source_revoke just before the + * backing data is freed avoids accesses to freed data structures. The + * sources will return 0. + */ +void stats_fs_source_revoke(struct stats_fs_source *source); + +/** + * stats_fs_source_get - increases refcount of source + * @source: a pointer to the source whose refcount will be increased + */ +void stats_fs_source_get(struct stats_fs_source *source); + +/** + * stats_fs_source_put - decreases refcount of source and deletes if needed + * @source: a pointer to the source whose refcount will be decreased + * + * If refcount arrives to zero, take care of deleting + * and free the source resources and files, by firstly recursively calling + * stats_fs_source_remove_subordinate to the child and then deleting + * its own files and allocations. + */ +void stats_fs_source_put(struct stats_fs_source *source); + +/** + * stats_fs_initialized - returns true if stats_fs fs has been registered + */ +bool stats_fs_initialized(void); + +#else + +#include + +/* + * We do not return NULL from these functions if CONFIG_STATS_FS is not enabled + * so users have a chance to detect if there was a real error or not. We don't + * want to duplicate the design decision mistakes of procfs and devfs again. + */ + +static inline struct stats_fs_source *stats_fs_source_create(const char *fmt, + ...) +{ + return ERR_PTR(-ENODEV); +} + +static inline int stats_fs_source_add_values(struct stats_fs_source *source, + struct stats_fs_value *val, + void *base_ptr) +{ + return -ENODEV; +} + +static inline void +stats_fs_source_add_subordinate(struct stats_fs_source *parent, + struct stats_fs_source *child) +{ } + +static inline void +stats_fs_source_remove_subordinate(struct stats_fs_source *parent, + struct stats_fs_source *child) +{ } + +static inline int stats_fs_source_get_value(struct stats_fs_source *source, + struct stats_fs_value *val, + uint64_t *ret) +{ + return -ENODEV; +} + +static inline int +stats_fs_source_get_value_by_name(struct stats_fs_source *source, char *name, + uint64_t *ret) +{ + return -ENODEV; +} + +static inline int stats_fs_source_clear(struct stats_fs_source *source, + struct stats_fs_value *val) +{ + return -ENODEV; +} + +static inline void stats_fs_source_revoke(struct stats_fs_source *source) +{ } + +static inline void stats_fs_source_get(struct stats_fs_source *source) +{ } + +static inline void stats_fs_source_put(struct stats_fs_source *source) +{ } + +static inline bool stats_fs_initialized(void) +{ } + +#endif + +#endif