From patchwork Sat Apr 6 13:52:01 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lukas Wunner X-Patchwork-Id: 13619825 Received: from bmailout3.hostsharing.net (bmailout3.hostsharing.net [176.9.242.62]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 576552C1A3; Sat, 6 Apr 2024 13:53:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=176.9.242.62 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712411588; cv=none; b=JkDPo/hgkErCJLHIK3A4aMJa8VQZwEWl0phz3RP7yq2d9WpbR2FO2e2EY8pDKclckjzBlAFrjR0WY2tD+Dq73GNa32Gy6PmZK3AoJx4iY8rvbE8zO7lSUlr1hPZd0dLK7jQMPDfuBjRZWHdIHzj7HiTIJINGOKbH6sJVUIsR6Hc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712411588; c=relaxed/simple; bh=KaB+H/QNRD1ZBpVagmhzPb+DI/HWOBbGyYx+42MjjhA=; h=Message-Id:In-Reply-To:References:From:Date:Subject:To:Cc; b=QACPOzWN+wOGQs43EFd28mp/05k0NeU6ez/KBaEgmxI19H6XqSjixDpKdKnTtC84c+TXFK0zPiu2vAZDLWxd+7LwageR0/JBDqaB+nD32zzDyWV6yZQgqdqPrD1PihWecEquxPgEEdudlwGBoc4n9xxL9mtN4n1gsCI1ntXj7dQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=wunner.de; spf=pass smtp.mailfrom=wunner.de; arc=none smtp.client-ip=176.9.242.62 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=wunner.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=wunner.de Received: from h08.hostsharing.net (h08.hostsharing.net [IPv6:2a01:37:1000::53df:5f1c:0]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "*.hostsharing.net", Issuer "RapidSSL TLS RSA CA G1" (verified OK)) by bmailout3.hostsharing.net (Postfix) with ESMTPS id 71931100DA1BC; Sat, 6 Apr 2024 15:53:04 +0200 (CEST) Received: by h08.hostsharing.net (Postfix, from userid 100393) id 483384E2B1B; Sat, 6 Apr 2024 15:53:04 +0200 (CEST) Message-Id: <5ed62b197a442ec6db53d8746d9d806dd0576e2d.1712410202.git.lukas@wunner.de> In-Reply-To: References: From: Lukas Wunner Date: Sat, 6 Apr 2024 15:52:01 +0200 Subject: [PATCH 1/2] sysfs: Add sysfs_bin_attr_simple_read() helper To: Greg Kroah-Hartman , "Rafael J. Wysocki" , linux-kernel@vger.kernel.org Cc: Michael Ellerman , linuxppc-dev@lists.ozlabs.org, linux-acpi@vger.kernel.org, Jean Delvare , Ard Biesheuvel , linux-efi@vger.kernel.org, Zhenyu Wang , Zhi Wang , intel-gvt-dev@lists.freedesktop.org, Daniel Lezcano , linux-pm@vger.kernel.org, Luis Chamberlain , linux-modules@vger.kernel.org Precedence: bulk X-Mailing-List: linux-modules@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: When drivers expose a bin_attribute in sysfs which is backed by a buffer in memory, a common pattern is to set the @private and @size members in struct bin_attribute to the buffer's location and size. The ->read() callback then merely consists of a single memcpy() call. It's not even necessary to perform bounds checks as these are already handled by sysfs_kf_bin_read(). However each driver is so far providing its own ->read() implementation. The pattern is sufficiently frequent to merit a public helper, so add sysfs_bin_attr_simple_read() as well as BIN_ATTR_SIMPLE_RO() and BIN_ATTR_SIMPLE_ADMIN_RO() macros to ease declaration of such bin_attributes and reduce LoC and .text section size. Signed-off-by: Lukas Wunner Reviewed-by: Greg Kroah-Hartman --- fs/sysfs/file.c | 27 +++++++++++++++++++++++++++ include/linux/sysfs.h | 15 +++++++++++++++ 2 files changed, 42 insertions(+) diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c index 6b7652f..289b57d 100644 --- a/fs/sysfs/file.c +++ b/fs/sysfs/file.c @@ -783,3 +783,30 @@ int sysfs_emit_at(char *buf, int at, const char *fmt, ...) return len; } EXPORT_SYMBOL_GPL(sysfs_emit_at); + +/** + * sysfs_bin_attr_simple_read - read callback to simply copy from memory. + * @file: attribute file which is being read. + * @kobj: object to which the attribute belongs. + * @attr: attribute descriptor. + * @buf: destination buffer. + * @off: offset in bytes from which to read. + * @count: maximum number of bytes to read. + * + * Simple ->read() callback for bin_attributes backed by a buffer in memory. + * The @private and @size members in struct bin_attribute must be set to the + * buffer's location and size before the bin_attribute is created in sysfs. + * + * Bounds check for @off and @count is done in sysfs_kf_bin_read(). + * Negative value check for @off is done in vfs_setpos() and default_llseek(). + * + * Returns number of bytes written to @buf. + */ +ssize_t sysfs_bin_attr_simple_read(struct file *file, struct kobject *kobj, + struct bin_attribute *attr, char *buf, + loff_t off, size_t count) +{ + memcpy(buf, attr->private + off, count); + return count; +} +EXPORT_SYMBOL_GPL(sysfs_bin_attr_simple_read); diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h index 326341c..a7d725f 100644 --- a/include/linux/sysfs.h +++ b/include/linux/sysfs.h @@ -371,6 +371,17 @@ struct bin_attribute bin_attr_##_name = __BIN_ATTR_ADMIN_RO(_name, _size) #define BIN_ATTR_ADMIN_RW(_name, _size) \ struct bin_attribute bin_attr_##_name = __BIN_ATTR_ADMIN_RW(_name, _size) +#define __BIN_ATTR_SIMPLE_RO(_name, _mode) { \ + .attr = { .name = __stringify(_name), .mode = _mode }, \ + .read = sysfs_bin_attr_simple_read, \ +} + +#define BIN_ATTR_SIMPLE_RO(_name) \ +struct bin_attribute bin_attr_##_name = __BIN_ATTR_SIMPLE_RO(_name, 0444) + +#define BIN_ATTR_SIMPLE_ADMIN_RO(_name) \ +struct bin_attribute bin_attr_##_name = __BIN_ATTR_SIMPLE_RO(_name, 0400) + struct sysfs_ops { ssize_t (*show)(struct kobject *, struct attribute *, char *); ssize_t (*store)(struct kobject *, struct attribute *, const char *, size_t); @@ -478,6 +489,10 @@ int sysfs_group_change_owner(struct kobject *kobj, __printf(3, 4) int sysfs_emit_at(char *buf, int at, const char *fmt, ...); +ssize_t sysfs_bin_attr_simple_read(struct file *file, struct kobject *kobj, + struct bin_attribute *attr, char *buf, + loff_t off, size_t count); + #else /* CONFIG_SYSFS */ static inline int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)