From mboxrd@z Thu Jan 1 00:00:00 1970 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 1C69121ABC5 for ; Fri, 18 Apr 2025 17:14:02 +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=1744996443; cv=none; b=rKrZ8qw7k3ivqxUXr433E54ZIWkOe8h7xv4XuUak2T/lHJJeIfYg/mIm/i5RBgqxllJjy9Hzy4zm12qKgPPmF9nqJBFFyFwYuH9M6SMgdWVmm/CnU5dF+rziQfPd1CVfOYanLcUiunSykn+G8lXtivf4NrZ/oDYt8sbWHi4fKh0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744996443; c=relaxed/simple; bh=S4zyoINK/k1VihcBkWzpPYAZOrOLyaqIzhpOR3LrUaE=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=I1zdEoq6QkQsI5rkJt40biDnRsQI6IzL/HkJh5qQqJnF1cS0VnmFBROLhPV5v0Hr33ZWMyddIZn5CiPDMTKil+KLWUxZG63jizPmPMkTtcw/JrAr5FDWvziQvhZXUJu/MRTghYGD5Vi5pM4VdbLcxf+JSVi4wzhliqJ/qWRfv5s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MdcG821q; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="MdcG821q" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A5C26C4CEF8; Fri, 18 Apr 2025 17:14:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1744996442; bh=S4zyoINK/k1VihcBkWzpPYAZOrOLyaqIzhpOR3LrUaE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MdcG821qLrET2cEAZCIKLuK1FnCxCXBc+mjC8dSRjVN9MHz7T2t+73rsyAaDtb8SN ACfWopbYL4woQUB8s6FM3GEUp1SiFfxQgp2F7bYvxD+MpJCx3XdjZP2k7tMVXL4xpW A0+JldJ32zs9bW5ZiIgIa3ZdNl1jx15IKlfd4MSbn8X+vBVuahfjpGZIwgL97cJvIY VIS+S+sF9Kox9RJYKW+oZwHcqmwG57mdbcbB1qZYTO18zW5kXgY4RiULSmRPkki2qe d4Rv9bjDShSAYNlxmPHNd/XPoS9Tk16t6hq+SyQ0RYudiBWeELQDIsZKWApFptmKUD 58zLhuuzaynTg== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id E8699CE13D2; Fri, 18 Apr 2025 10:14:01 -0700 (PDT) From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: kernel-team@meta.com, Andrew Morton , Kuniyuki Iwashima , Mateusz Guzik , Petr Mladek , Steven Rostedt , John Ogness , Sergey Senozhatsky , Jon Pan-Doh , Bjorn Helgaas , Karolina Stolarek , "Paul E. McKenney" Subject: [PATCH v2 ratelimit 07/14] ratelimit: Count misses due to lock contention Date: Fri, 18 Apr 2025 10:13:52 -0700 Message-Id: <20250418171359.1187719-7-paulmck@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <4edcefb0-cdbd-4422-8a08-ffc091de158e@paulmck-laptop> References: <4edcefb0-cdbd-4422-8a08-ffc091de158e@paulmck-laptop> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The ___ratelimit() function simply returns zero ("do ratelimiting") if the trylock fails, but does not adjust the ->missed field. This means that the resulting dropped printk()s are dropped silently, which could seriously confuse people trying to do console-log-based debugging. Therefore, increment the ->missed field upon trylock failure. Signed-off-by: Paul E. McKenney Cc: Andrew Morton Cc: Kuniyuki Iwashima Cc: Mateusz Guzik Cc: Petr Mladek Cc: Steven Rostedt Cc: John Ogness Cc: Sergey Senozhatsky --- lib/ratelimit.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/lib/ratelimit.c b/lib/ratelimit.c index 18703f92d73e7..19ad3cdbd1711 100644 --- a/lib/ratelimit.c +++ b/lib/ratelimit.c @@ -44,8 +44,10 @@ int ___ratelimit(struct ratelimit_state *rs, const char *func) * in addition to the one that will be printed by * the entity that is holding the lock already: */ - if (!raw_spin_trylock_irqsave(&rs->lock, flags)) + if (!raw_spin_trylock_irqsave(&rs->lock, flags)) { + ratelimit_state_inc_miss(rs); return 0; + } if (!rs->begin) rs->begin = jiffies; -- 2.40.1