All of lore.kernel.org
 help / color / mirror / Atom feed
From: 王贇 <yun.wang@linux.alibaba.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Guo Ren <guoren@kernel.org>, Ingo Molnar <mingo@redhat.com>,
	"James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
	Helge Deller <deller@gmx.de>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.de>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Jiri Kosina <jikos@kernel.org>, Miroslav Benes <mbenes@suse.cz>,
	Petr Mladek <pmladek@suse.com>,
	Joe Lawrence <joe.lawrence@redhat.com>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Nicholas Piggin <npiggin@gmail.com>,
	Jisheng Zhang <jszhang@kernel.org>,
	linux-csky@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	linux-riscv@lists.infradead.org, live-patching@vger.kernel.org
Subject: Re: [PATCH v6 1/2] ftrace: disable preemption when recursion locked
Date: Wed, 27 Oct 2021 11:09:29 +0800	[thread overview]
Message-ID: <e8bb4220-4895-e55d-4aea-cdd265fdfd38@linux.alibaba.com> (raw)
In-Reply-To: <20211026225552.72a7ee79@rorschach.local.home>



On 2021/10/27 上午10:55, Steven Rostedt wrote:
> On Wed, 27 Oct 2021 10:34:13 +0800
> 王贇 <yun.wang@linux.alibaba.com> wrote:
> 
>> +/*
>> + * Preemption will be enabled (if it was previously enabled).
>> + */
>>  static __always_inline void trace_clear_recursion(int bit)
>>  {
>> +	WARN_ON_ONCE(bit < 0);
> 
> Can you send a v7 without the WARN_ON.
> 
> This is an extremely hot path, and this will cause noticeable overhead.
> 
> If something were to call this with bit < 0, then it would crash and
> burn rather quickly.

I see, if the problem will be notified anyway then it's fine, v7 on the way.

Regards,
Michael Wang

> 
> -- Steve
> 
> 
>> +
>> +	preempt_enable_notrace();
>>  	barrier();
>>  	trace_recursion_clear(bit);
>>  }

WARNING: multiple messages have this Message-ID (diff)
From: 王贇 <yun.wang@linux.alibaba.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Guo Ren <guoren@kernel.org>, Ingo Molnar <mingo@redhat.com>,
	"James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
	Helge Deller <deller@gmx.de>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.de>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Jiri Kosina <jikos@kernel.org>, Miroslav Benes <mbenes@suse.cz>,
	Petr Mladek <pmladek@suse.com>,
	Joe Lawrence <joe.lawrence@redhat.com>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Nicholas Piggin <npiggin@gmail.com>,
	Jisheng Zhang <jszhang@kernel.org>,
	linux-csky@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	linux-riscv@lists.infradead.org, live-patching@vger.kernel.org
Subject: Re: [PATCH v6 1/2] ftrace: disable preemption when recursion locked
Date: Wed, 27 Oct 2021 11:09:29 +0800	[thread overview]
Message-ID: <e8bb4220-4895-e55d-4aea-cdd265fdfd38@linux.alibaba.com> (raw)
In-Reply-To: <20211026225552.72a7ee79@rorschach.local.home>



On 2021/10/27 上午10:55, Steven Rostedt wrote:
> On Wed, 27 Oct 2021 10:34:13 +0800
> 王贇 <yun.wang@linux.alibaba.com> wrote:
> 
>> +/*
>> + * Preemption will be enabled (if it was previously enabled).
>> + */
>>  static __always_inline void trace_clear_recursion(int bit)
>>  {
>> +	WARN_ON_ONCE(bit < 0);
> 
> Can you send a v7 without the WARN_ON.
> 
> This is an extremely hot path, and this will cause noticeable overhead.
> 
> If something were to call this with bit < 0, then it would crash and
> burn rather quickly.

I see, if the problem will be notified anyway then it's fine, v7 on the way.

Regards,
Michael Wang

> 
> -- Steve
> 
> 
>> +
>> +	preempt_enable_notrace();
>>  	barrier();
>>  	trace_recursion_clear(bit);
>>  }

_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

WARNING: multiple messages have this Message-ID (diff)
From: 王贇 <yun.wang@linux.alibaba.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: "Peter Zijlstra \(Intel\)" <peterz@infradead.org>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	"James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
	Guo Ren <guoren@kernel.org>, Jisheng Zhang <jszhang@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	live-patching@vger.kernel.org, linux-riscv@lists.infradead.org,
	Miroslav Benes <mbenes@suse.cz>,
	Joe Lawrence <joe.lawrence@redhat.com>,
	Helge Deller <deller@gmx.de>,
	x86@kernel.org, linux-csky@vger.kernel.org,
	Ingo Molnar <mingo@redhat.com>, Petr Mladek <pmladek@suse.com>,
	Albert Ou <aou@eecs.berkeley.edu>, Jiri Kosina <jikos@kernel.org>,
	Nicholas Piggin <npiggin@gmail.com>,
	Borislav Petkov <bp@alien8.de>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-parisc@vger.kernel.org, linux-kernel@vger.kernel.org,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Paul Mackerras <paulus@samba.org>,
	linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v6 1/2] ftrace: disable preemption when recursion locked
Date: Wed, 27 Oct 2021 11:09:29 +0800	[thread overview]
Message-ID: <e8bb4220-4895-e55d-4aea-cdd265fdfd38@linux.alibaba.com> (raw)
In-Reply-To: <20211026225552.72a7ee79@rorschach.local.home>



On 2021/10/27 上午10:55, Steven Rostedt wrote:
> On Wed, 27 Oct 2021 10:34:13 +0800
> 王贇 <yun.wang@linux.alibaba.com> wrote:
> 
>> +/*
>> + * Preemption will be enabled (if it was previously enabled).
>> + */
>>  static __always_inline void trace_clear_recursion(int bit)
>>  {
>> +	WARN_ON_ONCE(bit < 0);
> 
> Can you send a v7 without the WARN_ON.
> 
> This is an extremely hot path, and this will cause noticeable overhead.
> 
> If something were to call this with bit < 0, then it would crash and
> burn rather quickly.

I see, if the problem will be notified anyway then it's fine, v7 on the way.

Regards,
Michael Wang

> 
> -- Steve
> 
> 
>> +
>> +	preempt_enable_notrace();
>>  	barrier();
>>  	trace_recursion_clear(bit);
>>  }

  reply	other threads:[~2021-10-27  3:09 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-27  2:32 [PATCH v6 0/2] fix & prevent the missing preemption disabling 王贇
2021-10-27  2:32 ` 王贇
2021-10-27  2:34 ` [PATCH v6 1/2] ftrace: disable preemption when recursion locked 王贇
2021-10-27  2:34   ` 王贇
2021-10-27  2:55   ` Steven Rostedt
2021-10-27  2:55     ` Steven Rostedt
2021-10-27  2:55     ` Steven Rostedt
2021-10-27  3:09     ` 王贇 [this message]
2021-10-27  3:09       ` 王贇
2021-10-27  3:09       ` 王贇
2021-10-27  2:34 ` [PATCH v6 2/2] ftrace: do CPU checking after preemption disabled 王贇
2021-10-27  2:34   ` 王贇

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=e8bb4220-4895-e55d-4aea-cdd265fdfd38@linux.alibaba.com \
    --to=yun.wang@linux.alibaba.com \
    --cc=James.Bottomley@HansenPartnership.com \
    --cc=aou@eecs.berkeley.edu \
    --cc=benh@kernel.crashing.org \
    --cc=bp@alien8.de \
    --cc=deller@gmx.de \
    --cc=guoren@kernel.org \
    --cc=hpa@zytor.com \
    --cc=jikos@kernel.org \
    --cc=joe.lawrence@redhat.com \
    --cc=jpoimboe@redhat.com \
    --cc=jszhang@kernel.org \
    --cc=linux-csky@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-parisc@vger.kernel.org \
    --cc=linux-riscv@lists.infradead.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=live-patching@vger.kernel.org \
    --cc=mbenes@suse.cz \
    --cc=mhiramat@kernel.org \
    --cc=mingo@redhat.com \
    --cc=mpe@ellerman.id.au \
    --cc=npiggin@gmail.com \
    --cc=palmer@dabbelt.com \
    --cc=paul.walmsley@sifive.com \
    --cc=paulus@samba.org \
    --cc=peterz@infradead.org \
    --cc=pmladek@suse.com \
    --cc=rostedt@goodmis.org \
    --cc=tglx@linutronix.de \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.