From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 04097364024; Tue, 16 Jun 2026 15:49:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781624959; cv=none; b=mALkBPDcMYKMkL9Jk3bpTO8+XZS6TqYtvzNkgdjxcL0BegzYOpIc2XHO0ELTIaqmD8XDLh9HJzrmSBLXSbwM6gEmNDYKkid1zX06d43GCa/X2BUA635jq3qdm5ZJcFzBBgIQj4uVcBds80ZjvmQ8R0zWKwaeZlZRM/0+6qRBYd0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781624959; c=relaxed/simple; bh=ttKy+xCBStkIWPr5F238oXonuklsXYFD4ComUS8DTkc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=mFVBrFiS1sF3ZedIGU2iXkBNdOZYhkUFOxD52/nEdFzaE8F89GdDhG60U3vWS/9pA6rFU6ff/BrfUUKvfMC4ByKOs3Pnaqj9eXHRx+NUgJv3M0su2lUe2YEM+MlmSkfeZY+X5oBzmx/JrRnDoe7jPOGm4n9C2DyRnRc4LCBXvQw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=VUDdn8WC; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="VUDdn8WC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 601CA1F000E9; Tue, 16 Jun 2026 15:49:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1781624956; bh=O2HoLgLBcW284sP9d8Tinbx8UDCVo2MjpMgw8TfXTB0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=VUDdn8WCjcmC0DeOp7eo/Kn5Okt7M9WqP/UwSja6EAbOTYGCNJkQew0VSXTQTSj5x Kxc2OzxzRjrERpz6BIM8hu6sRaeg62GVOQr5tGBu6B5PFoJKnVq5cO3Q6woDeOTyBQ IFl4C5rRPm7/1zvEW7pwDWGBgX03AjGKUr0NAieI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Florian Zeitz , Kurt Kanzenbach , Sebastian Andrzej Siewior , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.18 057/325] ptp: vclock: Switch from RCU to SRCU Date: Tue, 16 Jun 2026 20:27:33 +0530 Message-ID: <20260616145100.533501242@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260616145057.827196531@linuxfoundation.org> References: <20260616145057.827196531@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kurt Kanzenbach [ Upstream commit 672bd0519e27c357c43b7f8c0d653fce3817d06e ] 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@schettke.com/ Fixes: 67d93ffc0f3c ("ptp: vclock: use mutex to fix "sleep on atomic" bug") Signed-off-by: Kurt Kanzenbach Reviewed-by: Sebastian Andrzej Siewior Link: https://patch.msgid.link/20260529-vclock_rcu-v2-1-02a5531fab92@linutronix.de Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- 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 64c95045651787..295a64bdd846f2 100644 --- a/drivers/ptp/ptp_vclock.c +++ b/drivers/ptp/ptp_vclock.c @@ -19,6 +19,8 @@ static DEFINE_SPINLOCK(vclock_hash_lock); static DEFINE_READ_MOSTLY_HASHTABLE(vclock_hash, 8); +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) spin_unlock(&vclock_hash_lock); - synchronize_rcu(); + synchronize_srcu(&vclock_srcu); } 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 = vclock_index % HASH_SIZE(vclock_hash); struct ptp_vclock *vclock; - u64 ns; u64 vclock_ns = 0; + int srcu_idx; + u64 ns; ns = ktime_to_ns(*hwtstamp); - rcu_read_lock(); + srcu_idx = srcu_read_lock(&vclock_srcu); - 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 != vclock_index) continue; @@ -294,7 +298,7 @@ ktime_t ptp_convert_timestamp(const ktime_t *hwtstamp, int vclock_index) break; } - rcu_read_unlock(); + srcu_read_unlock(&vclock_srcu, srcu_idx); return ns_to_ktime(vclock_ns); } -- 2.53.0