From: 王贇 <yun.wang@linux.alibaba.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Miroslav Benes <mbenes@suse.cz>, 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>, 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 v5 1/2] ftrace: disable preemption when recursion locked
Date: Wed, 27 Oct 2021 09:54:13 +0800 [thread overview]
Message-ID: <3d897161-7b74-944a-f2a0-07311436fbd9@linux.alibaba.com> (raw)
In-Reply-To: <20211026080117.366137a5@gandalf.local.home>
On 2021/10/26 下午8:01, Steven Rostedt wrote:
> On Tue, 26 Oct 2021 17:48:10 +0800
> 王贇 <yun.wang@linux.alibaba.com> wrote:
>
>>> The two comments should be updated too since Steven removed the "bit == 0"
>>> trick.
>>
>> Could you please give more hint on how will it be correct?
>>
>> I get the point that bit will no longer be 0, there are only -1 or > 0 now
>> so trace_test_and_set_recursion() will disable preemption on bit > 0 and
>> trace_clear_recursion() will enabled it since it should only be called when
>> bit > 0 (I remember we could use a WARN_ON here now :-P).
>>
>>>
>>>> @@ -178,7 +187,7 @@ static __always_inline void trace_clear_recursion(int bit)
>>>> * tracing recursed in the same context (normal vs interrupt),
>>>> *
>>>> * Returns: -1 if a recursion happened.
>>>> - * >= 0 if no recursion
>>>> + * > 0 if no recursion.
>>>> */
>>>> static __always_inline int ftrace_test_recursion_trylock(unsigned long ip,
>>>> unsigned long parent_ip)
>>>
>>> And this change would not be correct now.
>>
>> I thought it will no longer return 0 so I change it to > 0, isn't that correct?
>
> No it is not. I removed the bit + 1 return value, which means it returns the
> actual bit now. Which is 0 or more.
Ah, the return is bit not val, I must be drunk...
My apologize for the stupid comments... I'll send a v6 for this patch
only to fix that, please let me know if this is not a good way to fix
few lines of comments.
Regards,
Michael Wang
>
> -- Steve
>
WARNING: multiple messages have this Message-ID (diff)
From: 王贇 <yun.wang@linux.alibaba.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Miroslav Benes <mbenes@suse.cz>, 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>, 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 v5 1/2] ftrace: disable preemption when recursion locked
Date: Wed, 27 Oct 2021 09:54:13 +0800 [thread overview]
Message-ID: <3d897161-7b74-944a-f2a0-07311436fbd9@linux.alibaba.com> (raw)
In-Reply-To: <20211026080117.366137a5@gandalf.local.home>
On 2021/10/26 下午8:01, Steven Rostedt wrote:
> On Tue, 26 Oct 2021 17:48:10 +0800
> 王贇 <yun.wang@linux.alibaba.com> wrote:
>
>>> The two comments should be updated too since Steven removed the "bit == 0"
>>> trick.
>>
>> Could you please give more hint on how will it be correct?
>>
>> I get the point that bit will no longer be 0, there are only -1 or > 0 now
>> so trace_test_and_set_recursion() will disable preemption on bit > 0 and
>> trace_clear_recursion() will enabled it since it should only be called when
>> bit > 0 (I remember we could use a WARN_ON here now :-P).
>>
>>>
>>>> @@ -178,7 +187,7 @@ static __always_inline void trace_clear_recursion(int bit)
>>>> * tracing recursed in the same context (normal vs interrupt),
>>>> *
>>>> * Returns: -1 if a recursion happened.
>>>> - * >= 0 if no recursion
>>>> + * > 0 if no recursion.
>>>> */
>>>> static __always_inline int ftrace_test_recursion_trylock(unsigned long ip,
>>>> unsigned long parent_ip)
>>>
>>> And this change would not be correct now.
>>
>> I thought it will no longer return 0 so I change it to > 0, isn't that correct?
>
> No it is not. I removed the bit + 1 return value, which means it returns the
> actual bit now. Which is 0 or more.
Ah, the return is bit not val, I must be drunk...
My apologize for the stupid comments... I'll send a v6 for this patch
only to fix that, please let me know if this is not a good way to fix
few lines of comments.
Regards,
Michael Wang
>
> -- Steve
>
_______________________________________________
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 v5 1/2] ftrace: disable preemption when recursion locked
Date: Wed, 27 Oct 2021 09:54:13 +0800 [thread overview]
Message-ID: <3d897161-7b74-944a-f2a0-07311436fbd9@linux.alibaba.com> (raw)
In-Reply-To: <20211026080117.366137a5@gandalf.local.home>
On 2021/10/26 下午8:01, Steven Rostedt wrote:
> On Tue, 26 Oct 2021 17:48:10 +0800
> 王贇 <yun.wang@linux.alibaba.com> wrote:
>
>>> The two comments should be updated too since Steven removed the "bit == 0"
>>> trick.
>>
>> Could you please give more hint on how will it be correct?
>>
>> I get the point that bit will no longer be 0, there are only -1 or > 0 now
>> so trace_test_and_set_recursion() will disable preemption on bit > 0 and
>> trace_clear_recursion() will enabled it since it should only be called when
>> bit > 0 (I remember we could use a WARN_ON here now :-P).
>>
>>>
>>>> @@ -178,7 +187,7 @@ static __always_inline void trace_clear_recursion(int bit)
>>>> * tracing recursed in the same context (normal vs interrupt),
>>>> *
>>>> * Returns: -1 if a recursion happened.
>>>> - * >= 0 if no recursion
>>>> + * > 0 if no recursion.
>>>> */
>>>> static __always_inline int ftrace_test_recursion_trylock(unsigned long ip,
>>>> unsigned long parent_ip)
>>>
>>> And this change would not be correct now.
>>
>> I thought it will no longer return 0 so I change it to > 0, isn't that correct?
>
> No it is not. I removed the bit + 1 return value, which means it returns the
> actual bit now. Which is 0 or more.
Ah, the return is bit not val, I must be drunk...
My apologize for the stupid comments... I'll send a v6 for this patch
only to fix that, please let me know if this is not a good way to fix
few lines of comments.
Regards,
Michael Wang
>
> -- Steve
>
next prev parent reply other threads:[~2021-10-27 1:55 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-26 3:14 [PATCH v5 0/2] fix & prevent the missing preemption disabling 王贇
2021-10-26 3:14 ` 王贇
2021-10-26 3:15 ` [PATCH v5 1/2] ftrace: disable preemption when recursion locked 王贇
2021-10-26 3:15 ` 王贇
2021-10-26 9:35 ` Miroslav Benes
2021-10-26 9:35 ` Miroslav Benes
2021-10-26 9:35 ` Miroslav Benes
2021-10-26 9:48 ` 王贇
2021-10-26 9:48 ` 王贇
2021-10-26 9:48 ` 王贇
2021-10-26 12:01 ` Steven Rostedt
2021-10-26 12:01 ` Steven Rostedt
2021-10-26 12:01 ` Steven Rostedt
2021-10-27 1:54 ` 王贇 [this message]
2021-10-27 1:54 ` 王贇
2021-10-27 1:54 ` 王贇
2021-10-27 2:26 ` Steven Rostedt
2021-10-27 2:26 ` Steven Rostedt
2021-10-27 2:26 ` Steven Rostedt
2021-10-27 2:28 ` 王贇
2021-10-27 2:28 ` 王贇
2021-10-27 2:28 ` 王贇
2021-10-27 2:11 ` [PATCH v6] " 王贇
2021-10-27 2:11 ` 王贇
2021-10-27 2:24 ` 王贇
2021-10-27 2:24 ` 王贇
2021-10-26 3:15 ` [PATCH v5 2/2] ftrace: do CPU checking after preemption disabled 王贇
2021-10-26 3:15 ` 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=3d897161-7b74-944a-f2a0-07311436fbd9@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.