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 9718A2E62D6 for ; Thu, 3 Apr 2025 21:15:17 +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=1743714917; cv=none; b=MSoiVXDkP0kDnsIzpCFTsSWy1FRouP6F4QXoFz7YzmG+BzTmbwpSonVquePeh7m4yl5fNMxJfy6iEdyMcgy1LtOmK3L8w/O6meFaNs/3OJpkO9IJg0+Neh320KxN2tBsu8cZG+uDFDta1Zgtr8UljGkDCCm4ISjsuBgFjcoHofE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743714917; c=relaxed/simple; bh=S4zyoINK/k1VihcBkWzpPYAZOrOLyaqIzhpOR3LrUaE=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=sHz03L4MNvbLpxwgRGBxOaI11nSGDUqm2KyBQlFW+x+mjXYPdUMAiozlPVYQp69+vqR4b5gw20ncfEq5diZ3IG5uM2BjnUmmgZJZJhOPMWp7MaKYfplCfWeZi+ImGwGjldZ1rSa7gQjjhF3upRmxmQ+3EGa2vpcbWwrcLv5hfCw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jzGkuS9w; 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="jzGkuS9w" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4848CC4CEED; Thu, 3 Apr 2025 21:15:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1743714917; bh=S4zyoINK/k1VihcBkWzpPYAZOrOLyaqIzhpOR3LrUaE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jzGkuS9wkwuXNU0HP1n82gg1nGdKKcZtluT+XU4GMZER+yj+0gccV574vGinpC8F5 LUQ2zcKjc7BY+WS/T7P8DeJJP2unu1hZzKz/Sv0MRdGr2asq/IuUed8czpODtGlxNW WPG4pTfMxg6GN6eZWflC4eGVkr6wxWnnYo9vSCFq2bjdO/6IVonUl5z7k8jMEIIqLO qbiw4itjVhh7bCB5CSMQzqaiwxKuwCAL/UkNCTvh2Fi0Z7LC4fb17gwvFTKLdR5jwx IRRw+bYXVSC/PgGLSR0lec3KC/DIH0q0nOlDAZKH3TGu2iKD7Lf8+z8yYgRT/P39cV gm0aLWHmvR+oQ== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id A2F7FCE0EDF; Thu, 3 Apr 2025 14:15:15 -0700 (PDT) From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: kernel-team@meta.com, "Paul E. McKenney" , Andrew Morton , Kuniyuki Iwashima , Mateusz Guzik , Petr Mladek , Steven Rostedt , John Ogness , Sergey Senozhatsky Subject: [PATCH RFC 6/9] ratelimit: Count misses due to lock contention Date: Thu, 3 Apr 2025 14:15:11 -0700 Message-Id: <20250403211514.985900-6-paulmck@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: References: 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