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Wysocki" , linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-coco@lists.linux.dev, alsa-devel@alsa-project.org Date: Thu, 22 Feb 2024 12:40:54 -0800 Message-ID: <170863445442.1479840.1818801787239831650.stgit@dwillia2-xfh.jf.intel.com> In-Reply-To: <170863444851.1479840.10249410842428140526.stgit@dwillia2-xfh.jf.intel.com> References: <170863444851.1479840.10249410842428140526.stgit@dwillia2-xfh.jf.intel.com> User-Agent: StGit/0.18-3-g996c MIME-Version: 1.0 Message-ID-Hash: RVRBVNKKO2XANNJLF3XFOIN3J6VZFEUL X-Message-ID-Hash: RVRBVNKKO2XANNJLF3XFOIN3J6VZFEUL X-MailFrom: dan.j.williams@intel.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; header-match-alsa-devel.alsa-project.org-0; header-match-alsa-devel.alsa-project.org-1; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header X-Mailman-Version: 3.3.9 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: It turns out that arch/x86/events/intel/core.c makes use of "empty" attributes. static struct attribute *empty_attrs; __init int intel_pmu_init(void) { struct attribute **extra_skl_attr = &empty_attrs; struct attribute **extra_attr = &empty_attrs; struct attribute **td_attr = &empty_attrs; struct attribute **mem_attr = &empty_attrs; struct attribute **tsx_attr = &empty_attrs; ... That breaks the assumption __first_visible() that expects that if grp->attrs is set then grp->attrs[0] must also be set and results in backtraces like: BUG: kernel NULL pointer dereference, address: 00rnel mode #PF: error_code(0x0000) - not-present ] PREEMPT SMP NOPTI CPU: 1 PID: 1 Comm: swapper/IP: 0010:exra_is_visible+0x14/0x20 ? exc_page_fault+0x68/0x190 internal_create_groups+0x42/0xa0 pmu_dev_alloc+0xc0/0xe0 perf_event_sysfs_init+0x580000000000 ]--- RIP: 0010:exra_is_visible+0x14/0 Check for non-empty attributes array before calling is_visible(). Reported-by: Pierre-Louis Bossart Closes: https://github.com/thesofproject/linux/pull/4799#issuecomment-1958537212 Fixes: 70317fd24b41 ("sysfs: Introduce a mechanism to hide static attribute_groups") Cc: Marc Herbert Cc: "Rafael J. Wysocki" Signed-off-by: Dan Williams Tested-by: Marc Herbert --- fs/sysfs/group.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c index ccb275cdabcb..8c63ba3cfc47 100644 --- a/fs/sysfs/group.c +++ b/fs/sysfs/group.c @@ -33,10 +33,10 @@ static void remove_files(struct kernfs_node *parent, static umode_t __first_visible(const struct attribute_group *grp, struct kobject *kobj) { - if (grp->attrs && grp->is_visible) + if (grp->attrs && grp->attrs[0] && grp->is_visible) return grp->is_visible(kobj, grp->attrs[0], 0); - if (grp->bin_attrs && grp->is_bin_visible) + if (grp->bin_attrs && grp->bin_attrs[0] && grp->is_bin_visible) return grp->is_bin_visible(kobj, grp->bin_attrs[0], 0); return 0; From patchwork Thu Feb 22 20:41:00 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dan Williams X-Patchwork-Id: 13568076 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 50339C48BF8 for ; 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X-IronPort-AV: E=McAfee;i="6600,9927,10992"; a="25358672" X-IronPort-AV: E=Sophos;i="6.06,179,1705392000"; d="scan'208";a="25358672" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orvoesa101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Feb 2024 12:41:01 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10992"; a="913585401" X-IronPort-AV: E=Sophos;i="6.06,179,1705392000"; d="scan'208";a="913585401" Received: from wyeh-mobl.amr.corp.intel.com (HELO dwillia2-xfh.jf.intel.com) ([10.209.77.87]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Feb 2024 12:41:00 -0800 Subject: [PATCH 2/3] sysfs: Document new "group visible" helpers From: Dan Williams To: gregkh@linuxfoundation.org Cc: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-coco@lists.linux.dev, alsa-devel@alsa-project.org Date: Thu, 22 Feb 2024 12:41:00 -0800 Message-ID: <170863446065.1479840.10697164014098377292.stgit@dwillia2-xfh.jf.intel.com> In-Reply-To: <170863444851.1479840.10249410842428140526.stgit@dwillia2-xfh.jf.intel.com> References: <170863444851.1479840.10249410842428140526.stgit@dwillia2-xfh.jf.intel.com> User-Agent: StGit/0.18-3-g996c MIME-Version: 1.0 Message-ID-Hash: AEVJ6IYOBZYDJNKNN3G7QC62LGIDFC56 X-Message-ID-Hash: AEVJ6IYOBZYDJNKNN3G7QC62LGIDFC56 X-MailFrom: dan.j.williams@intel.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; header-match-alsa-devel.alsa-project.org-0; header-match-alsa-devel.alsa-project.org-1; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header X-Mailman-Version: 3.3.9 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" Archived-At: List-Archive: <> List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: Add documentation and examples for how to use DEFINE_SYSFS_GROUP_VISIBLE() and SYSFS_GROUP_VISIBLE(). Recall that the motivation for this work is that it is easier to reason about the lifetime of statically defined sysfs attributes that become visible at device_add() time rather than dynamically adding them later. DEFINE_SYSFS_GROUP_VISIBLE() tackles one of the reasons to opt for dynamically created attributes which did not have a facility for hiding empty directories. Signed-off-by: Dan Williams --- include/linux/sysfs.h | 42 +++++++++++++++++++++++++++++++++++++++--- 1 file changed, 39 insertions(+), 3 deletions(-) diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h index a42642b277dd..dabf7f4f3581 100644 --- a/include/linux/sysfs.h +++ b/include/linux/sysfs.h @@ -105,8 +105,42 @@ struct attribute_group { #define SYSFS_GROUP_INVISIBLE 020000 /* - * The first call to is_visible() in the create / update path may - * indicate visibility for the entire group + * DEFINE_SYSFS_GROUP_VISIBLE(name): + * A helper macro to pair with the assignment of ".is_visible = + * SYSFS_GROUP_VISIBLE(name)", that arranges for the directory + * associated with a named attribute_group to optionally be hidden. + * This allows for static declaration of attribute_groups, and the + * simplification of attribute visibility lifetime that implies, + * without polluting sysfs with empty attribute directories. + * Ex. + * + * static umode_t example_attr_visible(struct kobject *kobj, + * struct attribute *attr, int n) + * { + * if (example_attr_condition) + * return 0; + * else if (ro_attr_condition) + * return 0444; + * return a->mode; + * } + * + * static bool example_group_visible(struct kobject *kobj) + * { + * if (example_group_condition) + * return false; + * return true; + * } + * + * DEFINE_SYSFS_GROUP_VISIBLE(example); + * + * static struct attribute_group example_group = { + * .name = "example", + * .is_visible = SYSFS_GROUP_VISIBLE(example), + * .attrs = &example_attrs, + * }; + * + * Note that it expects _attr_visible and _group_visible to + * be defined. */ #define DEFINE_SYSFS_GROUP_VISIBLE(name) \ static inline umode_t sysfs_group_visible_##name( \ @@ -119,7 +153,9 @@ struct attribute_group { /* * Same as DEFINE_SYSFS_GROUP_VISIBLE, but for groups with only binary - * attributes + * attributes. 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d="scan'208";a="25358682" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orvoesa101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Feb 2024 12:41:07 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10992"; a="913585407" X-IronPort-AV: E=Sophos;i="6.06,179,1705392000"; d="scan'208";a="913585407" Received: from wyeh-mobl.amr.corp.intel.com (HELO dwillia2-xfh.jf.intel.com) ([10.209.77.87]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Feb 2024 12:41:06 -0800 Subject: [PATCH 3/3] sysfs: Introduce DEFINE_SIMPLE_SYSFS_GROUP_VISIBLE() From: Dan Williams To: gregkh@linuxfoundation.org Cc: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-coco@lists.linux.dev, alsa-devel@alsa-project.org Date: Thu, 22 Feb 2024 12:41:06 -0800 Message-ID: <170863446625.1479840.10593839479268727913.stgit@dwillia2-xfh.jf.intel.com> In-Reply-To: <170863444851.1479840.10249410842428140526.stgit@dwillia2-xfh.jf.intel.com> References: <170863444851.1479840.10249410842428140526.stgit@dwillia2-xfh.jf.intel.com> User-Agent: StGit/0.18-3-g996c MIME-Version: 1.0 Message-ID-Hash: HOFLYZMI7LXRXK4MNV2VFV4V42EHSDKD X-Message-ID-Hash: HOFLYZMI7LXRXK4MNV2VFV4V42EHSDKD X-MailFrom: dan.j.williams@intel.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; header-match-alsa-devel.alsa-project.org-0; header-match-alsa-devel.alsa-project.org-1; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header X-Mailman-Version: 3.3.9 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: One of the first users of DEFINE_SYSFS_GROUP_VISIBLE() did this: static umode_t dp0_attr_visible(struct kobject *kobj, struct attribute *attr, int n) { struct sdw_slave *slave = dev_to_sdw_dev(kobj_to_dev(kobj)); if (slave->prop.dp0_prop) return attr->mode; return 0; } static bool dp0_group_visible(struct kobject *kobj) { struct sdw_slave *slave = dev_to_sdw_dev(kobj_to_dev(kobj)); if (slave->prop.dp0_prop) return true; return false; } DEFINE_SYSFS_GROUP_VISIBLE(dp0); ...i.e. the _group_visible() helper is identical to the _attr_visible() helper. Use the "simple" helper to reduce that to: static bool dp0_group_visible(struct kobject *kobj) { struct sdw_slave *slave = dev_to_sdw_dev(kobj_to_dev(kobj)); if (slave->prop.dp0_prop) return true; return false; } DEFINE_SIMPLE_SYSFS_GROUP_VISIBLE(dp0); Remove the need to specify per attribute visibility if the goal is to hide the entire group. Signed-off-by: Dan Williams --- include/linux/sysfs.h | 45 ++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 44 insertions(+), 1 deletion(-) diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h index dabf7f4f3581..326341c62385 100644 --- a/include/linux/sysfs.h +++ b/include/linux/sysfs.h @@ -140,7 +140,9 @@ struct attribute_group { * }; * * Note that it expects _attr_visible and _group_visible to - * be defined. + * be defined. For cases where individual attributes do not need + * separate visibility consideration, only entire group visibility at + * once, see DEFINE_SIMPLE_SYSFS_GROUP_VISIBLE(). */ #define DEFINE_SYSFS_GROUP_VISIBLE(name) \ static inline umode_t sysfs_group_visible_##name( \ @@ -151,6 +153,38 @@ struct attribute_group { return name##_attr_visible(kobj, attr, n); \ } +/* + * DEFINE_SIMPLE_SYSFS_GROUP_VISIBLE(name): + * A helper macro to pair with SYSFS_GROUP_VISIBLE() that like + * DEFINE_SYSFS_GROUP_VISIBLE() controls group visibility, but does + * not require the implementation of a per-attribute visibility + * callback. + * Ex. + * + * static bool example_group_visible(struct kobject *kobj) + * { + * if (example_group_condition) + * return false; + * return true; + * } + * + * DEFINE_SIMPLE_SYSFS_GROUP_VISIBLE(example); + * + * static struct attribute_group example_group = { + * .name = "example", + * .is_visible = SYSFS_GROUP_VISIBLE(example), + * .attrs = &example_attrs, + * }; + */ +#define DEFINE_SIMPLE_SYSFS_GROUP_VISIBLE(name) \ + static inline umode_t sysfs_group_visible_##name( \ + struct kobject *kobj, struct attribute *a, int n) \ + { \ + if (n == 0 && !name##_group_visible(kobj)) \ + return SYSFS_GROUP_INVISIBLE; \ + return a->mode; \ + } + /* * Same as DEFINE_SYSFS_GROUP_VISIBLE, but for groups with only binary * attributes. If an attribute_group defines both text and binary @@ -166,6 +200,15 @@ struct attribute_group { return name##_attr_visible(kobj, attr, n); \ } +#define DEFINE_SIMPLE_SYSFS_BIN_GROUP_VISIBLE(name) \ + static inline umode_t sysfs_group_visible_##name( \ + struct kobject *kobj, struct bin_attribute *a, int n) \ + { \ + if (n == 0 && !name##_group_visible(kobj)) \ + return SYSFS_GROUP_INVISIBLE; \ + return a->mode; \ + } + #define SYSFS_GROUP_VISIBLE(fn) sysfs_group_visible_##fn /*