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 006B519D88B; Tue, 27 Aug 2024 11:52:58 +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=1724759579; cv=none; b=qrq69gpkCCjkROXZmSvnBmdTgROE3dm12CcuWcbSC61JraqEYF+PCJQqf+VBN510TUWZuIJ5nFGL4N5moty5x9xPa24zT5jDwyyMH7LhFhKClle7GJBMYUdiZQaDv6dt2gqK3U4daTDD2cvtQMdh8npaM/x+J54SXAwP0GQMKro= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724759579; c=relaxed/simple; bh=DFWIEmoK+/fqJ5NdqkTGlRn2iJT4TOA+yIeHbCFUelY=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=kAF1esc1X4Hzbh5fbrtaeAOt1GQBE3mW+JXEAAAoO89mEWdJsJyQ3FTWx43DtvUQE1Az916eT2d8THbnrhh9yr8PtLw11K4gDemDNiDQuwWsuAFze86U9C9PjdTqVEpsDiYLCMzY9Ya/NwQjoRy8msC3VwazNDXADmO1+zEZU00= 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 7613FC51E5C; Tue, 27 Aug 2024 11:52:53 +0000 (UTC) Date: Tue, 27 Aug 2024 07:52:41 -0400 From: Steven Rostedt To: Zheng Yejian Cc: mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: Re: [PATCH] tracing: Mitigate possible softlockup in __tracing_open() Message-ID: <20240827075241.5cd652ae@rorschach.local.home> In-Reply-To: References: <20240824030343.3218618-1-zhengyejian@huaweicloud.com> <20240826103522.390faa85@gandalf.local.home> X-Mailer: Claws Mail 3.17.8 (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 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Tue, 27 Aug 2024 09:29:55 +0800 Zheng Yejian wrote: > > This is the wrong place to put this. If the problem is with > > tracing_iter_reset(), then add it there. > > > > while (ring_buffer_iter_peek(buf_iter, &ts)) { > > if (ts >= iter->array_buffer->time_start) > > break; > > entries++; > > ring_buffer_iter_advance(buf_iter); > > /* This could be a big loop */ > > cond_resched(); > > Do resched check every event peek, I'm afraid there will > be too many 're-schedule'. cond_resched() as the name suggests only schedules conditionally if NEED_RESCHED is set. This isn't a fast path (obviously, as it requires a cond_resched). -- Steve