From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-0031df01.pphosted.com (mx0a-0031df01.pphosted.com [205.220.168.131]) (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 E6F2748F845 for ; Mon, 19 Oct 2026 07:39:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=205.220.168.131 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792395596; cv=none; b=hmJcqwe4h79wZUa4sMA6lqGS+ZzEKri3i35pdy3BDuQrOdf20NRYZuxZ5yYZq47uksTnyIKFPw024diRt84FUNv0ouxlL0jHnqJ+cvAW6suDTJb8jdnAfH4+Om60De7t1wE/7jVtzzH5dhrmoR10y248U7HlwaylF/anUO1mT88= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792395596; c=relaxed/simple; bh=p07iEb35ew4rhOEg7En2KdbSWe0jhUN4Q6HAAyHT/Fs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=q2SUFegjVXRclfuFErV3+RZKjukX2kh8TjX7gSV+qNJcokCz9QYD7mbxNdTN924xj1eW+oT4fSACrmsjaWYnrcPqZv2wp1XD/PwuUF+PSsONC1vHtjv3hx33vD7vBkxPe82YoM1hKB7KW/+fFIcCVmi+dGPyZw6UP+mKVwCPSZs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oss.qualcomm.com; spf=pass smtp.mailfrom=oss.qualcomm.com; dkim=pass (2048-bit key) header.d=qualcomm.com header.i=@qualcomm.com header.b=i60YYQ6o; dkim=pass (2048-bit key) header.d=oss.qualcomm.com header.i=@oss.qualcomm.com header.b=NxI1aZNC; arc=none smtp.client-ip=205.220.168.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oss.qualcomm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=oss.qualcomm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=qualcomm.com header.i=@qualcomm.com header.b="i60YYQ6o"; dkim=pass (2048-bit key) header.d=oss.qualcomm.com header.i=@oss.qualcomm.com header.b="NxI1aZNC" Received: from pps.filterd (m0279867.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 69J4iqD42818412 for ; Mon, 19 Oct 2026 07:39:50 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=qualcomm.com; h= cc:content-transfer-encoding:date:from:in-reply-to:message-id :mime-version:references:subject:to; s=qcppdkim1; bh=+heyUUDe3z2 ElJaSEfijE4i66Qx9XUHm2pk2TCmmnhc=; b=i60YYQ6opTE+P2AaIX7k6+kAEPi hEGbxsKldg20TQ6BLoMWv7jlgm7FZE4+SkA9makEDbuIZsgvhtCQasGRGWc/RMuL LEs+gYArnQITbEX50uLCBFOl/vBTaHN8oDl8FYFyvHqYDCDYg8GpwG22noBMWOy6 ojp+286D+VIK+caEirxd/otCh2usPKV+isVqGoL+tMXxUnwthnDw20jSvPnMFP7r IMUC+nLWpAVVfUz8s1yA+m7pSqAUUtre9bLmU14P8r+TWu1Yj2kZiL1/no1G4wnp avcDWG0zG2aBohX24twb+MFC0cr+NumKAhWyiBnx9hnqVsxMktWk36A1U6A== Received: from mail-qk1-f199.google.com (mail-qk1-f199.google.com [209.85.222.199]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 4hbxqfwt51-1 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NOT) for ; Mon, 19 Oct 2026 07:39:49 +0000 (GMT) Received: by mail-qk1-f199.google.com with SMTP id af79cd13be357-934963b2bc0so368823485a.3 for ; Mon, 19 Oct 2026 00:39:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oss.qualcomm.com; s=google; t=1792395586; x=1793000386; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=+heyUUDe3z2ElJaSEfijE4i66Qx9XUHm2pk2TCmmnhc=; b=NxI1aZNCc36JfnOxjfPB6ALuR/s2ZNC7IO9N8Jkw/ibeHUXTC9gGJ9Tp28CsaGgRNI PsnPhPkwgUAMggGm1tXn1SLJ15jynyOtgTspaX0nCBgxDcJKdli6SdPa/6zdx746TehF alHMsJCAh3BPykqvBOBCUEpaWUAc03udjm/Abyz9eY7NkH1aA5Yqkl6BJ+gI8R0lSnBn NNjet043o7BjhdlRu1nUGz1XpRCtmnsvEun4UibnZqlVqrZVaoEsSgMrPb9h6bDI7DgL F+reXigfzFoSxYDWmFNr6Bkop0Ht7LUjmXPbCXEhpJOvYBsxIcHyd1tx/qu885ZXLa20 b8xw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1792395586; x=1793000386; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=+heyUUDe3z2ElJaSEfijE4i66Qx9XUHm2pk2TCmmnhc=; b=t4avygUpJ+MiN2/Y5VDN/T4DQ5vwfp3CCjvKSHILK4m+rNuAQ7JWodkZxTd3moxPzL a8yDKTQLgUMNv6EKb7bGQtdemN+bXLd6f0UZXswHk5opeRfwLwtSIqClnBHBEzR8z4VM 7kF7Rn3iFGVThj861mJ7ybl9fLPVaeHKF9RcwA/UZW9aEbhBkOrO2aHkTA6f8/RiQQCy lKaoF9DlPnk9WU31hb0fspn4BpBAZchPCJBx96mjQ6d0bcMjR1WiUZA1ZincxJ8dGM/l G/WCrj6tEx4/RgqC8V2IJUhM5XG6IQkCYR9JPA3Ab9nzFWpDCrxRpVfYsuK0IVRM4QF5 z0DQ== X-Forwarded-Encrypted: i=1; AKwUvBzIWs6+VUqqp1KbBAEdQ4Tl+PAe/6+tUq2pQl7amFhfuaRxyFnJ1PVUjO9WKWOojY7ZEtf2LkY1ew==@vger.kernel.org X-Gm-Message-State: AFq9FYKSqgTIbDoCUJzo0jt/pV4L7995a4v/OC9VPm5UvbCxuwz8ygW2 7OjvLffFu1hv39IT1AvU/JtVwTsgeVwUf6PyFOJFjjB3kb4H6zQaL1a67K+HfBBO4O5r/9VWDz2 93fG8BrtpzHeMkV7nFZzHdnNIwP3XumWf1xnFMdw9r7yAg4Yn9TmoHaoYDxOaIA== X-Gm-Gg: AYBFou0u+7+7YJAQpas/y9kLimFsT6go92NvjqYO8hO+JpnhNDNZFjcQcra6+rKE9PT 4ZNEAm5AP85TKvoH2XLkgOGwNwhVGcL92o2d1d5Gi8ni6gt+U2caxtwwc7IjImo0gZvvzeEn/AF FZy4zCCXwsTPghEQj9n26b/dH1PnPXvecAzK7IVlUhv1uTz4ldallQfoblz3Ni0+v25KFY9pXty avX05R0eBLJrIO3/w3nO+temp+9Kbfn48EY47D9CdeV7WgztYf8Y64Y7yeY2Ek4T3h4PEonWYGw 8xGEmqsBtkNOWUigNNsacxvGtlrgWnEmGpG/+cMeYpr39znXsILCwkER5wvOgQM2Bapc1ml6Zvn a4Xb53KWw8SMRAymPm0095R6qYUM= X-Received: by 2002:a05:620a:454a:b0:93b:c58c:d3be with SMTP id af79cd13be357-93f29d42f1emr1211043985a.37.1792395585499; Mon, 19 Oct 2026 00:39:45 -0700 (PDT) X-Received: by 2002:a05:620a:454a:b0:93b:c58c:d3be with SMTP id af79cd13be357-93f29d42f1emr1211039285a.37.1792395584963; Mon, 19 Oct 2026 00:39:44 -0700 (PDT) Received: from mai.box.freepro.com ([2a05:6e02:1041:c10:d01d:2002:4b7d:4c30]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4a1ce325107sm212812955e9.3.2026.10.19.00.39.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Oct 2026 00:39:44 -0700 (PDT) From: Daniel Lezcano To: rafael@kernel.org Cc: Len Brown , Jonathan Corbet , Shuah Khan , Viresh Kumar , Hans de Goede , =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= , Maximilian Luz , Shyam Sundar S K , Mark Pearson , "Derek J. Clark" , Daniel Lezcano , Zhang Rui , Lukasz Luba , Armin Wolf , Jai Luthra , Greg Kroah-Hartman , "Mario Limonciello (AMD)" , Jack Wu , Mario Limonciello , Zhang DM , linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-pm@vger.kernel.org, platform-driver-x86@vger.kernel.org Subject: [PATCH v2 1/5] platform profile: Separate handler locking from sysfs lifetime Date: Mon, 19 Oct 2026 09:39:04 +0200 Message-ID: <20261019073930.2352283-2-daniel.lezcano@oss.qualcomm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20261019073930.2352283-1-daniel.lezcano@oss.qualcomm.com> References: <20261019073930.2352283-1-daniel.lezcano@oss.qualcomm.com> Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Proofpoint-Spam-Info: AW1haW4tMjYxMDE5MDAzMCBTYWx0ZWRfXwY/yrJncNHDH Oqs38D6W2y0PH6Hxpe/da0YqZs0BjeBWhatxv51atrscg4BPmn41z2Gh3gameaxeUNDR3VyQhcf RVRBVLT+WbleXIXOrcpEpnKXs7crhi0= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDE5MDAzMCBTYWx0ZWRfX3XpCrlkPbqY+ oOVZOl/8U28lQPQLXYD075H2GEIsyMHVFe1Re4lD43x2daGyGLYxnTEQNHpLQQXScyKTe/e7qdT iO8amH0XI9f1x5BaWos2/Behm9jOdefk0HqOMR9RJftzavSo50vGkQ1dV+hX896a40EMMtAncQJ Ymb8cgz/pEdwoq5NAc1QptPDMv26FOhM8wesxqBVWoatdmsaO1mqO8iB40HhyIT/ejvLv92l9OL FOdHLpZvgOuIpKBOG3esBXDQ5DMK5VQoMHwsd/zA9+1pGqbH63fQZ83J2V/NAjolyUgILB4EKmz vWc97bf0BEdWLuvw5OGleLN7b9h2wZANeAkGvRsz3FeCgUWPyUWwyneT0u3dnJOp6MelxhjuzKe aEi4K3OsXAaRTb0OvFIdsqryw88kvIyRp06myPmnjqOdq4oZIDhv4E4folARs0ke6gWfTw/qUjD Pa8Y23W6UFLMilw1/vw== X-Proofpoint-ORIG-GUID: NqgWg_fq21gibiG_LpxN7BV-ejFtkzhX X-Proofpoint-GUID: NqgWg_fq21gibiG_LpxN7BV-ejFtkzhX X-Authority-Analysis: v=2.4 cv=RYMFmFtv c=1 sm=1 tr=0 ts=6ad5c945 cx=c_pps a=HLyN3IcIa5EE8TELMZ618Q==:117 a=xqWC_Br6kY4A:10 a=660iZSQnnn4A:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=eoimf2acIAo5FJnRuUoq:22 a=EUspDBNiAAAA:8 a=-LHEi2PMdtMAXt8Lty8A:9 a=bTQJ7kPSJx9SKPbeHEYW:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-10-19_02,2026-10-14_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 priorityscore=1501 impostorscore=0 spamscore=0 lowpriorityscore=0 malwarescore=0 phishscore=0 bulkscore=0 suspectscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610080000 definitions=main-2610190030 Registration and removal currently hold profile_lock across device_unregister() and sysfs_update_group(). These operations can remove sysfs attributes and wait for their active callbacks to finish. The profile read and write callbacks acquire profile_lock themselves, so a concurrent access can deadlock: Removal/update path Active sysfs callback ------------------- --------------------- acquire profile_lock hold kernfs active reference remove a sysfs attribute wait for profile_lock wait for its active references The removal path cannot finish until the callback returns, and the callback cannot return until the removal path releases profile_lock. This applies both to per-provider device teardown and to updates of the legacy aggregate attribute group. Commit 041142d7d252 ("ACPI: platform-profile: Fix possible deadlock in platform_profile_remove()") previously fixed this lock ordering by moving sysfs_remove_group() outside profile_lock. Commit 55b1e68134bf ("ACPI: platform_profile: Use guard(mutex) for register/unregister") reintroduced the issue by extending the mutex guard over sysfs_remove_group(). Later, commit 77be5cacb2c2 ("ACPI: platform_profile: Create class for ACPI platform profile") replaced that teardown with device_unregister() and sysfs_update_group(), still under the same mutex, extending the problem to class-device teardown and aggregate attribute updates. Simply dropping profile_lock around these operations is insufficient. Aggregate operations currently discover providers through the class device list. A provider being unregistered could therefore still be selected for an aggregate read, write or cycle while its sysfs files are being torn down. Concurrent registrations and removals would also race when updating aggregate attribute visibility. Introduce profile_registration_lock to serialize registration, removal and aggregate sysfs updates. Sysfs callbacks never acquire this mutex. Retain profile_lock for profile operations and use it to protect an explicit list of handlers participating in the aggregate interface. Add a handler to that list only after device_register() succeeds. On removal, unlink it under profile_lock before calling device_unregister(). Acquiring profile_lock first waits for any aggregate operation already using the handler to complete; unlinking prevents later aggregate operations from finding it. Release profile_lock before draining sysfs callbacks, allowing active per-provider callbacks to complete before the device is released. Apply the same unlink-before-unregister ordering to registration error cleanup. Walk this list for aggregate reads, writes and profile cycling, and use its emptiness to determine aggregate attribute visibility. The class devices remain the per-provider userspace interface. There can now be an interval between removing the last handler from the list and removing the aggregate attributes. Explicitly reject choices reads and writes during that interval: the intersection bitmap starts with every bit set, so an empty traversal must not advertise all profiles or report a successful write without updating a provider. This separates aggregate membership from class device teardown while preserving the existing class and ACPI sysfs interfaces. Fixes: 55b1e68134bf ("ACPI: platform_profile: Use guard(mutex) for register/unregister") Assisted-by: OpenCode:gpt-6.1-sol Signed-off-by: Daniel Lezcano --- drivers/acpi/platform_profile.c | 75 ++++++++++++++++++--------------- 1 file changed, 42 insertions(+), 33 deletions(-) diff --git a/drivers/acpi/platform_profile.c b/drivers/acpi/platform_profile.c index 79d2e92e5c28..f98ce4cda02c 100644 --- a/drivers/acpi/platform_profile.c +++ b/drivers/acpi/platform_profile.c @@ -8,6 +8,7 @@ #include #include #include +#include #include #include #include @@ -15,8 +16,12 @@ #define to_pprof_handler(d) (container_of(d, struct platform_profile_handler, dev)) static DEFINE_MUTEX(profile_lock); +/* Serialize registration and sysfs updates without blocking sysfs callbacks. */ +static DEFINE_MUTEX(profile_registration_lock); +static LIST_HEAD(profile_handlers); struct platform_profile_handler { + struct list_head node; const char *name; struct device dev; int minor; @@ -44,6 +49,22 @@ static_assert(ARRAY_SIZE(profile_names) == PLATFORM_PROFILE_LAST); static DEFINE_IDA(platform_profile_ida); +static int profile_walk_handlers(void *data, + int (*fn)(struct device *dev, void *data)) +{ + struct platform_profile_handler *handler; + int ret; + + lockdep_assert_held(&profile_lock); + list_for_each_entry(handler, &profile_handlers, node) { + ret = fn(&handler->dev, data); + if (ret) + return ret; + } + + return 0; +} + /** * _commmon_choices_show - Show the available profile choices * @choices: The available profile choices @@ -306,20 +327,18 @@ static ssize_t platform_profile_choices_show(struct kobject *kobj, int err; scoped_cond_guard(mutex_intr, return -ERESTARTSYS, &profile_lock) { - err = class_for_each_device(&platform_profile_class, NULL, - &data, _aggregate_choices); + err = profile_walk_handlers(&data, _aggregate_choices); if (err) return err; if (data.count == 1) { - err = class_for_each_device(&platform_profile_class, NULL, - &data, _remove_hidden_choices); + err = profile_walk_handlers(&data, _remove_hidden_choices); if (err) return err; } } /* no profile handler registered any more */ - if (bitmap_empty(data.aggregate, PLATFORM_PROFILE_LAST)) + if (!data.count || bitmap_empty(data.aggregate, PLATFORM_PROFILE_LAST)) return -EINVAL; return _commmon_choices_show(data.aggregate, buf); @@ -384,8 +403,7 @@ static ssize_t platform_profile_show(struct kobject *kobj, int err; scoped_cond_guard(mutex_intr, return -ERESTARTSYS, &profile_lock) { - err = class_for_each_device(&platform_profile_class, NULL, - &profile, _aggregate_profiles); + err = profile_walk_handlers(&profile, _aggregate_profiles); if (err) return err; } @@ -423,15 +441,13 @@ static ssize_t platform_profile_store(struct kobject *kobj, return -EINVAL; scoped_cond_guard(mutex_intr, return -ERESTARTSYS, &profile_lock) { - ret = class_for_each_device(&platform_profile_class, NULL, - &data, _aggregate_choices); + ret = profile_walk_handlers(&data, _aggregate_choices); if (ret) return ret; - if (!test_bit(i, data.aggregate)) + if (!data.count || !test_bit(i, data.aggregate)) return -EOPNOTSUPP; - ret = class_for_each_device(&platform_profile_class, NULL, &i, - _store_and_notify); + ret = profile_walk_handlers(&i, _store_and_notify); if (ret) return ret; } @@ -450,22 +466,11 @@ static struct attribute *platform_profile_attrs[] = { NULL }; -static int profile_class_registered(struct device *dev, const void *data) -{ - return 1; -} - static umode_t profile_class_is_visible(struct kobject *kobj, struct attribute *attr, int idx) { - struct device *dev; - - dev = class_find_device(&platform_profile_class, NULL, NULL, profile_class_registered); - if (!dev) - return 0; - - put_device(dev); + guard(mutex)(&profile_lock); - return attr->mode; + return list_empty(&profile_handlers) ? 0 : attr->mode; } static const struct attribute_group platform_profile_group = { @@ -502,8 +507,7 @@ int platform_profile_cycle(void) int err; scoped_cond_guard(mutex_intr, return -ERESTARTSYS, &profile_lock) { - err = class_for_each_device(&platform_profile_class, NULL, - &profile, _aggregate_profiles); + err = profile_walk_handlers(&profile, _aggregate_profiles); if (err) return err; @@ -512,8 +516,7 @@ int platform_profile_cycle(void) profile == PLATFORM_PROFILE_LAST) return -EINVAL; - err = class_for_each_device(&platform_profile_class, NULL, - &data, _aggregate_choices); + err = profile_walk_handlers(&data, _aggregate_choices); if (err) return err; @@ -525,8 +528,7 @@ int platform_profile_cycle(void) PLATFORM_PROFILE_LAST, profile + 1); - err = class_for_each_device(&platform_profile_class, NULL, &next, - _store_and_notify); + err = profile_walk_handlers(&next, _store_and_notify); if (err) return err; @@ -583,7 +585,7 @@ struct device *platform_profile_register(struct device *dev, const char *name, } } - guard(mutex)(&profile_lock); + guard(mutex)(&profile_registration_lock); /* create class interface for individual handler */ minor = ida_alloc(&platform_profile_ida, GFP_KERNEL); @@ -604,6 +606,8 @@ struct device *platform_profile_register(struct device *dev, const char *name, put_device(ppdev); goto cleanup_ida; } + scoped_guard(mutex, &profile_lock) + list_add_tail(&to_pprof_handler(ppdev)->node, &profile_handlers); sysfs_notify(acpi_kobj, NULL, "platform_profile"); @@ -614,6 +618,8 @@ struct device *platform_profile_register(struct device *dev, const char *name, return ppdev; cleanup_cur: + scoped_guard(mutex, &profile_lock) + list_del(&to_pprof_handler(ppdev)->node); device_unregister(ppdev); cleanup_ida: @@ -636,7 +642,10 @@ void platform_profile_remove(struct device *dev) pprof = to_pprof_handler(dev); - guard(mutex)(&profile_lock); + guard(mutex)(&profile_registration_lock); + + scoped_guard(mutex, &profile_lock) + list_del(&pprof->node); ida_free(&platform_profile_ida, pprof->minor); device_unregister(&pprof->dev); -- 2.43.0