From nobody Mon Jun 8 11:07:05 2026 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 9014137AA9E; Fri, 29 May 2026 17:11:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780074711; cv=none; b=DfIhAHHP2QUPb1YgtByfA0rX+xyat3aFWniHxkGiYfzK/Ql568ize0RYmnccH6exsB+SaY417HsQPm2p4lftUdPzhwRETjl43SSMdGPKygyIoOpK3oAY8+axVRF2OqCLIZQiga/y7NXUH9brxdIauwL9jfSYx2IJqki6og2ZnGw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780074711; c=relaxed/simple; bh=pjjuZGuuJXmsUWl7MVLNzeOQFxPgEMleEtB5P7MyQAQ=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:To:Cc; b=iSCfJaqytauS1odz5b7dM0VTyeirkf/SdE29FY3i9QUuEE9f2gmprPcZ2ZniWJdveRv+f+nQgvgTjlWvpMcg996yAcUyneVDm/gNLnuB5mY9jwHytE+1lqCoDhV7q25Uy58hrwkGy6VI+cpOEbLHXxzWI35SqLxZ62DYV0qogxA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=SjOYjnfC; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=Ar345ICT; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="SjOYjnfC"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="Ar345ICT" From: Kurt Kanzenbach DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1780074708; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=GPdv3BzuzelntFIDcB2WQfKo5PqptnQiWyMY07m9XWk=; b=SjOYjnfC+QLfw0JVWuCGIj29BMCZH2zVXCsvQoVrdZ5op5CE565zFezjHyckURa29ITYaZ lW5nlXHcYgVRAWrrevyP130qVGBZYOaLYKLkN6bBcBXaP6tYISSuvr5rzRLoFVKAt0TS5r G4cFlDafKUnFCEIqf3T1atGCAjSrKDXmj2Yq7mhI1xFlqCPTMifKmt0mlTDd7hfUl4hRVn eAYECS8UL6ornem6VsW6OShe8Lx3xoEu9VcrCjlNIVCp1u24eU9rIyd7WWUEh8c/Att19A lkHxJ2apqH5r2GEZAWzMBthsE1G9hOenQMu0f/GSpG6wDACMWK0QK5NQkbj2rQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1780074708; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=GPdv3BzuzelntFIDcB2WQfKo5PqptnQiWyMY07m9XWk=; b=Ar345ICTycnij4lKbRjSZu77PFumKANmsOOumPd0v2jRixFBAA96PUXuuWGPOhz33VlK7z /tpLThIXWkFLT/AQ== Date: Fri, 29 May 2026 19:11:47 +0200 Subject: [PATCH net v2] ptp: vclock: Switch from RCU to SRCU Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260529-vclock_rcu-v2-1-02a5531fab92@linutronix.de> X-B4-Tracking: v=1; b=H4sIANLIGWoC/22NwQ6CMBBEf4Xs2Zq2iAgn/8MQI9tVVklr2tJgC P8u4NXjTN68mSCQZwpQZxN4ShzY2SXoXQbY3eyDBJslg5b6KAutRMLe4evqcRCkK6xQyRLzFpb B29Odx012AUsRml8ZhvZJGFfNinUcovOf7TKpDf5nT0ooUWF+KFCdWlPqc892iN5ZHveGoJnn+ QvyJNlVvwAAAA== X-Change-ID: 20260521-vclock_rcu-e29c9c107c3b To: Richard Cochran , Yangbo Lu , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: =?utf-8?q?=C3=8D=C3=B1igo_Huguet?= , Miroslav Lichvar , Blanco Alcaine Hector , "Christopher S. Hall" , Sebastian Andrzej Siewior , Florian Zeitz , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Kurt Kanzenbach X-Developer-Signature: v=1; a=openpgp-sha256; l=2672; i=kurt@linutronix.de; h=from:subject:message-id; bh=pjjuZGuuJXmsUWl7MVLNzeOQFxPgEMleEtB5P7MyQAQ=; b=owEBbQKS/ZANAwAKAcGT0fKqRnOCAcsmYgBqGcjTjO261o3esWkVi5KltpPWYajUOHmk5UerS kcqCD7qj+GJAjMEAAEKAB0WIQS8ub+yyMN909/bWZLBk9HyqkZzggUCahnI0wAKCRDBk9HyqkZz gt24EACWp2FBlKzYClPjROOseFsklKPkyZoJ0/aKJrbOYLyKVAocLzLjShz84NiBtDDa0xg3fy7 uGXZjAYfolOoweO5+efg2BMllwsKxM12HoPNgZH3rqiIc+Qxtl+h7cCLfS66ezhdY+C/1wN2Lm3 IDWEg2mwTHguwl8UeMfXnw0KUpUwvonIFmud9fJb9bbBRBFYtqc+x+fYSokhwrZB+Z8Oll8GY3g KCoq4d/yBMQ5vbWnsAVIU4hbjmP4vxfJFF1i5GCNXyJ0vYzmjo0eZOUCkOf/faPaZFV8vpQlShN fiXztRi5pvbGkmyOyALGeA+swyFVUMOKFj/VxEH+GOIHIJslsr4I89SFzaWo8yfDBh981WPcUvN O78GP4+F4gCjOiVOgVqSQPse56yfQ32pGu82k8bqxdFosRNFx1JUUNCwtiVZ3ETMBJb1lxXZ4Ru XM09Y99Ce+z8hUvqxox5s2v5Uy2b/obiGHJeBR0SHnmByi1yKCGxdiNLRvKF/EGJDT4tVBAWr4e Gi8KccVfs9j5KkbcO8OduGpUptxWVziT55RX0nY/edC/jl8e+j9WycYjmwr/tcoYVeex1vuuu+9 sK5U4dbKuqQdj1Kv3XjSAl5wPQrnWSV7LeHEL+8Hx4yLUSD3KiIFG62HaQKgauJKe6r0pMPt/4W EosnXSrgK08Wy/w== X-Developer-Key: i=kurt@linutronix.de; a=openpgp; fpr=BCB9BFB2C8C37DD3DFDB5992C193D1F2AA467382 The usage of PTP vClocks leads immediately to the following issues with ptp4l with LOCKDEP and DEBUG_ATOMIC_SLEEP enabled: "BUG: sleeping function called from invalid context". ptp_convert_timestamp() acquires a mutex_t within a RCU read section. This is illegal, because acquiring a mutex_t can result in voluntary scheduling request which is not allowed within a RCU read section. Replace the RCU usage with SRCU where sleeping is allowed. Reported-by: Florian Zeitz Closes: https://lore.kernel.org/all/00a8cce8-410e-4038-98af-49be6d93d7bd@sc= hettke.com/ Fixes: 67d93ffc0f3c ("ptp: vclock: use mutex to fix "sleep on atomic" bug") Signed-off-by: Kurt Kanzenbach Reviewed-by: Sebastian Andrzej Siewior --- Changes in v2: - Remove RFC. No comments. - Link to v1: https://patch.msgid.link/20260521-vclock_rcu-v1-1-9c345c18bd7= 2@linutronix.de --- drivers/ptp/ptp_vclock.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/drivers/ptp/ptp_vclock.c b/drivers/ptp/ptp_vclock.c index 915a4f6defc9..84cb527f59cc 100644 --- a/drivers/ptp/ptp_vclock.c +++ b/drivers/ptp/ptp_vclock.c @@ -19,6 +19,8 @@ static DEFINE_SPINLOCK(vclock_hash_lock); =20 static DEFINE_READ_MOSTLY_HASHTABLE(vclock_hash, 8); =20 +DEFINE_STATIC_SRCU(vclock_srcu); + static void ptp_vclock_hash_add(struct ptp_vclock *vclock) { spin_lock(&vclock_hash_lock); @@ -37,7 +39,7 @@ static void ptp_vclock_hash_del(struct ptp_vclock *vclock) =20 spin_unlock(&vclock_hash_lock); =20 - synchronize_rcu(); + synchronize_srcu(&vclock_srcu); } =20 static int ptp_vclock_adjfine(struct ptp_clock_info *ptp, long scaled_ppm) @@ -276,14 +278,16 @@ ktime_t ptp_convert_timestamp(const ktime_t *hwtstamp= , int vclock_index) { unsigned int hash =3D vclock_index % HASH_SIZE(vclock_hash); struct ptp_vclock *vclock; - u64 ns; u64 vclock_ns =3D 0; + int srcu_idx; + u64 ns; =20 ns =3D ktime_to_ns(*hwtstamp); =20 - rcu_read_lock(); + srcu_idx =3D srcu_read_lock(&vclock_srcu); =20 - hlist_for_each_entry_rcu(vclock, &vclock_hash[hash], vclock_hash_node) { + hlist_for_each_entry_srcu(vclock, &vclock_hash[hash], vclock_hash_node, + srcu_read_lock_held(&vclock_srcu)) { if (vclock->clock->index !=3D vclock_index) continue; =20 @@ -294,7 +298,7 @@ ktime_t ptp_convert_timestamp(const ktime_t *hwtstamp, = int vclock_index) break; } =20 - rcu_read_unlock(); + srcu_read_unlock(&vclock_srcu, srcu_idx); =20 return ns_to_ktime(vclock_ns); } --- base-commit: 422b5233b607476ac7176bfa2a101b9a103d7653 change-id: 20260521-vclock_rcu-e29c9c107c3b Best regards, -- =20 Kurt Kanzenbach