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 1215122A4E9 for ; Thu, 17 Sep 2026 00:37:26 +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=1789605448; cv=none; b=dj2lAGmB6JsoODD0aj/my3OH1bgx8iNVXkZLaFSncnW94BPs1zMKcDPTwSiHpOuscyaUpM1HFfXeVNLqh0t4fG4sOnjOMzIIVIra456VaxqIvHrCz8ZsaknTiCh6nG6CPvMiUb2xq1rAGVT52kWoqOYCstnqraklJv8hKzoetJU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789605448; c=relaxed/simple; bh=L9KWRXNQWBB6dAAE9kERSC+EFEYeLxOlaCos9u7lJgo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=BCutekfwxquc+bd1I1e4BOVMLXHnXf8UT3DjUzOuhN4kdSnG5B7TuJUyIPpX7DvSRuH6tAbop6EQTapS35qC52zif0pnvusmMrdjDm4WsPUVL3KCWQiOsECHF9HCzFnXUGdFbCrBVaChCqdIz/PEuCC6baBvzL1R+QWYJvTjY88= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=gJZ4vMXg; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="gJZ4vMXg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 272F91F000FF; Thu, 17 Sep 2026 00:37:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789605446; bh=otuDLhE1lgU3jW936gD8thQ2qazFnOEFEzRjPRBsoO4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=gJZ4vMXgsrRyngZ6+as0KdecUxpmILmJspxg8CoFai1o0j4ks2F+15GvF/pl4eE23 JCBNVHguL1nmi0lU9IwJVL941mcrTS2uKvY/pRXwNxLqCFF5nbiNU8EgskVF6iCWeh mHvST84tGa1LxTuYg3W5an5WDo8mRGxLDWAPlMGa2fjsxNetNrTbASybmgFVTmhapj EmjDkDUEwoKmfIxHlarwJ7KbY4fHTpR8i8A6N6lB6QT2yv/D+YtQG41nD9NP9dNVm4 LUCzFo6dWaavujbHvmTcLy5TW7i/nKbLgSc7navVA0rfpexDoCr/7aQXTseGDCQihd RftwvPUSAUtlA== From: Sasha Levin To: stable@vger.kernel.org Cc: Sebastian Andrzej Siewior , Vincent Donnefort , Steven Rostedt , Sasha Levin Subject: [PATCH 5.15.y] ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters() Date: Wed, 16 Sep 2026 20:37:24 -0400 Message-ID: <20260917003724.3443633-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026091640-capacity-finalize-8fbc@gregkh> References: <2026091640-capacity-finalize-8fbc@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Sebastian Andrzej Siewior [ Upstream commit 815e07c8fe885a87751c2496a30ae0dcd4118210 ] rb_wake_up_waiters() is a irq_work callback which is initialized with init_irq_work(). As such it will be invoked in thread context on PREEMPT_RT. Invoking the callback in IRQ context on PREEMPT_RT is not an option due its usage of wake_up_all(). Since this callback may run in thread context, it needs to acquire ring_buffer_per_cpu::reader_lock with disabling interrupts and may not assume that they are disabled. Use raw_spinlock_irqsave() to acquire ring_buffer_per_cpu::reader_lock. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260911102152.YEtwkBj9@linutronix.de Fixes: 68282dd930ea3 ("ring-buffer: Fix resetting of shortest_full") Reviewed-by: Vincent Donnefort Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Steven Rostedt [ Replaced scoped_guard() with explicit raw_spin_lock_irqsave()/raw_spin_unlock_irqrestore() calls for GNU89 compatibility. ] Signed-off-by: Sasha Levin --- kernel/trace/ring_buffer.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 84f3b0d0bc887..9c43f01fa2c2a 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -877,15 +877,15 @@ static void rb_wake_up_waiters(struct irq_work *work) /* Only cpu_buffer sets the above flags */ struct ring_buffer_per_cpu *cpu_buffer = container_of(rbwork, struct ring_buffer_per_cpu, irq_work); + unsigned long flags; - /* Called from interrupt context */ - raw_spin_lock(&cpu_buffer->reader_lock); + raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); rbwork->wakeup_full = false; rbwork->full_waiters_pending = false; /* Waking up all waiters, they will reset the shortest full */ cpu_buffer->shortest_full = 0; - raw_spin_unlock(&cpu_buffer->reader_lock); + raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); wake_up_all(&rbwork->full_waiters); } -- 2.53.0