From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sai Prakash Ranjan Subject: Re: [PATCH 2/6] pstore: Add event tracing support Date: Wed, 19 Sep 2018 02:43:34 +0530 Message-ID: References: <20180917193426.41c99fd5@gandalf.local.home> <20180918164434.472294f3@gandalf.local.home> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20180918164434.472294f3@gandalf.local.home> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Steven Rostedt Cc: Ingo Molnar , Laura Abbott , Kees Cook , Anton Vorontsov , Rob Herring , devicetree@vger.kernel.org, Colin Cross , Jason Baron , Tony Luck , Arnd Bergmann , Catalin Marinas , Will Deacon , Joel Fernandes , Masami Hiramatsu , Joe Perches , Jim Cromie , Rajendra Nayak , Vivek Gautam , Sibi Sankar , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-msm@vg List-Id: devicetree@vger.kernel.org On 9/19/2018 2:14 AM, Steven Rostedt wrote: > On Tue, 18 Sep 2018 23:22:48 +0530 > Sai Prakash Ranjan wrote: > >> On 9/18/2018 5:04 AM, Steven Rostedt wrote: >>> >>> It looks like pstore_event_call() gets called from a trace event. You >>> can't call kmalloc() from one. One thing is that kmalloc has >>> tracepoints itself. You trace those you just entered an infinite loop. >>> >>> >> >> Ok will remove it in v2. But any alternative way to do this? > > I think I describe it below. > Ok got it, will change and post the 2nd version soon. >> >>>> + >>>> + event_call = fbuffer->trace_file->event_call; >>>> + if (!event_call || !event_call->event.funcs || >>>> + !event_call->event.funcs->trace) >>>> + goto fail_event; >>>> + >>>> + event = &fbuffer->trace_file->event_call->event; >>>> + >>>> + spin_lock_irqsave(&psinfo->buf_lock, flags); >>>> + >>>> + trace_seq_init(&iter->seq); >>>> + iter->ent = fbuffer->entry; >>> >>> I guess what you are doing is needing to translate the raw data into >>> ascii output, and need the trace_iterator to do so. >>> >>> You are already under a psinfo->buf_lock. Add a dummy iterator to that >>> and use it instead. >>> >>> trace_seq_init(&psinfo->iter->seq); >>> >>>> + event_call->event.funcs->trace(iter, 0, event); >>> >>> (psinfo->iter, 0 , event); >>> >>> etc. >>> >> >> Sure, will update in v2. >> >>>> + trace_seq_putc(&iter->seq, 0); >>>> + >>>> + if (seq->size > psinfo->bufsize) >>>> + seq->size = psinfo->bufsize; >>>> + >>>> + s = &iter->seq; >>>> + seq = &s->seq; >>>> + >>>> + record.buf = (char *)(seq->buffer); >>>> + record.size = seq->len; >>>> + psinfo->write(&record); >>>> + >>>> + spin_unlock_irqrestore(&psinfo->buf_lock, flags); >>> >>> You may also need to convert these spin_locks into raw_spin_locks as >>> when PREEMPT_RT enters the kernel you don't want them to turn into >>> mutexes. >>> >>> But that can be another patch. >>> >> >> I will change this in v2, but can't we have it in same patch? > > I suggested a separate patch because buf_lock is used elsewhere. > Changing it to "raw_spin_lock" will affect more than just what this > patch series does. Thus, I recommend making it a separate patch to keep > this patch series from being more intrusive than it needs to be. > Sure, thanks a lot. -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation