From patchwork Tue Mar 12 15:30:02 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 13590148 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 206DE58AD4; Tue, 12 Mar 2024 15:27:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710257278; cv=none; b=TqqOaqcWGCPa/7h58wQvqxUB1A0VwgXHK6GeUXy84CgGEVF918/FO5yRKszW+0K90l0HL7rhGGygvF+Awq+5G4Jk/pUo8IDToe7AwBLX9V2QswPurUmIvuV8xU5o9s9MvsHtrEhvOx7AqFWvQeLrCd5yrO7agx6PSQT1CktF5vU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710257278; c=relaxed/simple; bh=6b7L4Sbs/Q00lM4mIgsLsO8GHS3s4iVoc322HloRkfo=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type; b=s2b8c553faPY86HDXXLxMEVq465sucPF3Gzj3clVjBuavLcQmY5rxEcYhHdo7Ev/q4QP8/F4KLBWMPjVyDHpyB1hIUUR8cobrjQ5UwYhSQodJYergWU+bbL0ATOAC/A6z0m15m+IYhtbRaQWm5bvP41mCnZpC6xxYNrrCXrM58g= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id C73D6C433C7; Tue, 12 Mar 2024 15:27:56 +0000 (UTC) Date: Tue, 12 Mar 2024 11:30:02 -0400 From: Steven Rostedt To: LKML , Linux Trace Kernel Cc: Masami Hiramatsu , Mathieu Desnoyers , kernel test robot , Nathan Chancellor Subject: [PATCH] tracing: Use strcmp() in __assign_str() WARN_ON() check Message-ID: <20240312113002.00031668@gandalf.local.home> X-Mailer: Claws Mail 3.19.1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: "Steven Rostedt (Google)" The WARN_ON() check in __assign_str() to catch where the source variable to the macro doesn't match the source variable to __string() gives an error in clang: >> include/trace/events/sunrpc.h:703:4: warning: result of comparison against a string literal is unspecified (use an explicit string comparison function instead) [-Wstring-compare] 670 | __assign_str(progname, "unknown"); That's because the __assign_str() macro has: WARN_ON_ONCE((src) != __data_offsets.dst##_ptr_); Where "src" is a string literal. Clang warns when comparing a string literal directly as it is undefined to what the value of the literal is. Since this is still to make sure the same string that goes to __string() is the same as __assign_str(), for string literals do a test for that and then use strcmp() in those cases Note that this depends on commit 51270d573a8d ("tracing/net_sched: Fix tracepoints that save qdisc_dev() as a string") being applied, as this was what found that bug. Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202402292111.KIdExylU-lkp@intel.com/ Fixes: 433e1d88a3be ("tracing: Add warning if string in __assign_str() does not match __string()") Signed-off-by: Steven Rostedt (Google) --- include/trace/stages/stage6_event_callback.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/include/trace/stages/stage6_event_callback.h b/include/trace/stages/stage6_event_callback.h index a0c15f67eabe..83da83a0c14f 100644 --- a/include/trace/stages/stage6_event_callback.h +++ b/include/trace/stages/stage6_event_callback.h @@ -35,7 +35,9 @@ do { \ char *__str__ = __get_str(dst); \ int __len__ = __get_dynamic_array_len(dst) - 1; \ - WARN_ON_ONCE((src) != __data_offsets.dst##_ptr_); \ + WARN_ON_ONCE(__builtin_constant_p(src) ? \ + strcmp((src), __data_offsets.dst##_ptr_) : \ + (src) != __data_offsets.dst##_ptr_); \ memcpy(__str__, __data_offsets.dst##_ptr_ ? : \ EVENT_NULL_STR, __len__); \ __str__[__len__] = '\0'; \