From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792498812; b=DeCj+/tgp3Hm8odS/vHWSv3+sEpuN1xgYMS/9YTw7voFPYyeLd0l8/r2RFE77iBh6N4H WIW5A7mNGRj5qMU7ShzkXHhJm+O8sblN+zSAXxFHU/9coMNSGPvq9dW0pozlHBlanq+7q fMidijqPKM2dopMnhCZ1BMiAF8qwtGn+lpGNijkrFUt9nAhFptkSXEc+IwZTJTUuuUBMw nv0hJsRzBgvdZ0VAS5CGmxgaSNaN7H0M2eSIHE9W4im17NTkuwLb958IsOp/tkP5Lms3C cPgjolVga5qjbHsOVX0HK1j87Sk7xMF97wd5TO8v2uJXW/zCWqt6oYWVSTtrjZ0pU+Q== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792498812; h=Received:DKIM-Signature:Received:Message-ID:User-Agent:Date:From:To: Cc:Subject:References:MIME-Version:Content-Type; bh=jUdPUXgNaj3Cp0RL8qgLl9uXKgsmy6m5HypnnGpwoGM=; b=TrK95s65UEfvipQsDatwAdExrXYPtch1w+ZYpt6FlNh2h0ZxdMQcugyR0Um5WcN3nDuY ML3XWbyulWCORzVmFwSkPwib2hLgAefIXX6BKuLFj1koeOKkzkwO6yXHNd6X9qzR4jBCs UPVEdiVgzWjNCLKmR5ip0S+j1A+EYKjeT64AJlxsYzKlKDepQ3XjthktOh8B/EMLg4vvD +9Of+lTS4NgFMbv34uXNsZFC+pAedONPv8W8S9yEQt8jRgHszvDCKhFpSoNw6bC/zkjMl GMNzsyNwIWQlTD3e6Ru8IFyoGuZmYzbDXK4HFIJ2X3itAY8OpWJBgkkIz8Dy5S8AU0A== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=oqRoKq7d; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5D00B606A33E; Tue, 20 Oct 2026 12:20:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=oqRoKq7d Received: by smtp.kernel.org (Postfix) with ESMTPSA id F1F0C1F000C9; Tue, 20 Oct 2026 12:20:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792498812; bh=jUdPUXgNaj3Cp0RL8qgLl9uXKgsmy6m5HypnnGpwoGM=; h=Date:From:To:Cc:Subject:References; b=oqRoKq7drguhftX+AF6mEHiBDzIMBCoQJvnKvXJXgJPDmWs7nhh99FkEGr0Zp5cr4 wkSPtgrQ/wTDNzrGl1N/uWd1iOu51SUI+c0hHJCYI+oOcm98fhOOteLoz4f0GShbIR qNxOtpKQm6N3W69/ANa29Eu3AHkDoSsAiHN4BCPa0WkYYIurHrKDu+Yn3Fmydti1uG ms2LBA4RcOSRf9L/y4LcYihQgsnUl1big9w9Qycb+tfW07VeYFw7j6WPrk7SPiAwcv MtXjem76GG6M1CLweamxzGgTnAYRU7wXkdbZH2+5J8VrOWLfgc5Z0FM0oZJ861UCbq lxM+2dfStQvQQ== Received: from rostedt by gandalf with local (Exim 4.100.1) (envelope-from ) id 1xJ8p9-00000001y2p-0x9C; Tue, 20 Oct 2026 08:20:11 -0400 Message-ID: <20261020122011.033386537@kernel.org> User-Agent: quilt/0.69 Date: Tue, 20 Oct 2026 08:19:59 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , stable@vger.kernel.org, David Carlier Subject: [for-next][PATCH 3/6] tracing: Hold trace_types_lock when resetting last boot data from readers References: <20261020121956.600452831@kernel.org> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 From: David Carlier update_last_data_if_empty() is called from tracing_open() with O_TRUNC, tracing_read_pipe() and tracing_buffers_read() without trace_types_lock. Two readers can both pass the LAST_BOOT test and free module_delta twice, and a module notifier can update module_delta while it is being freed. Take trace_types_lock in those paths and keep the callers that already hold it on an unlocked variant. Cc: stable@vger.kernel.org Fixes: 32dc0042528d ("tracing: Reset last-boot buffers when reading out all cpu buffers") Link: https://patch.msgid.link/20261016061638.214847-2-devnexen@gmail.com Signed-off-by: David Carlier Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 96005a930b25..08614af8fad1 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3603,6 +3603,7 @@ static int tracing_single_release_tr(struct inode *inode, struct file *file) return single_release(inode, file); } +static bool __update_last_data_if_empty(struct trace_array *tr); static bool update_last_data_if_empty(struct trace_array *tr); static int tracing_open(struct inode *inode, struct file *file) @@ -4697,7 +4698,7 @@ tracing_set_trace_read(struct file *filp, char __user *ubuf, int tracer_init(struct tracer *t, struct trace_array *tr) { tracing_reset_online_cpus(&tr->array_buffer); - update_last_data_if_empty(tr); + __update_last_data_if_empty(tr); return t->init(tr); } @@ -5371,8 +5372,10 @@ static int tracing_wait_pipe(struct file *filp) return 1; } -static bool update_last_data_if_empty(struct trace_array *tr) +static bool __update_last_data_if_empty(struct trace_array *tr) { + lockdep_assert_held(&trace_types_lock); + if (!(tr->flags & TRACE_ARRAY_FL_LAST_BOOT)) return false; @@ -5387,6 +5390,16 @@ static bool update_last_data_if_empty(struct trace_array *tr) return true; } +static bool update_last_data_if_empty(struct trace_array *tr) +{ + /* Avoid the lock on the read path unless this is a last boot buffer */ + if (!(tr->flags & TRACE_ARRAY_FL_LAST_BOOT)) + return false; + + guard(mutex)(&trace_types_lock); + return __update_last_data_if_empty(tr); +} + /* * Consumer reader. */ @@ -6476,7 +6489,7 @@ int tracing_set_clock(struct trace_array *tr, const char *clockstr) ring_buffer_set_clock(tr->snapshot_buffer.buffer, trace_clocks[i].func); tracing_reset_online_cpus(&tr->snapshot_buffer); #endif - update_last_data_if_empty(tr); + __update_last_data_if_empty(tr); if (tr->scratch && !(tr->flags & TRACE_ARRAY_FL_LAST_BOOT)) { struct trace_scratch *tscratch = tr->scratch; -- 2.53.0