From: Miroslav Benes <mbenes@suse.cz>
To: 王贇 <yun.wang@linux.alibaba.com>
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,
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>,
Steven Rostedt <rostedt@goodmis.org>,
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: Tue, 26 Oct 2021 11:35:16 +0200 (CEST) [thread overview]
Message-ID: <alpine.LSU.2.21.2110261128120.28494@pobox.suse.cz> (raw)
In-Reply-To: <333cecfe-3045-8e0a-0c08-64ff590845ab@linux.alibaba.com>
Hi,
> diff --git a/include/linux/trace_recursion.h b/include/linux/trace_recursion.h
> index abe1a50..2bc1522 100644
> --- a/include/linux/trace_recursion.h
> +++ b/include/linux/trace_recursion.h
> @@ -135,6 +135,9 @@ static __always_inline int trace_get_context_bit(void)
> # define do_ftrace_record_recursion(ip, pip) do { } while (0)
> #endif
>
> +/*
> + * Preemption is promised to be disabled when return bit > 0.
> + */
> static __always_inline int trace_test_and_set_recursion(unsigned long ip, unsigned long pip,
> int start)
> {
> @@ -162,11 +165,17 @@ static __always_inline int trace_test_and_set_recursion(unsigned long ip, unsign
> current->trace_recursion = val;
> barrier();
>
> + preempt_disable_notrace();
> +
> return bit;
> }
>
> +/*
> + * Preemption will be enabled (if it was previously enabled).
> + */
> static __always_inline void trace_clear_recursion(int bit)
> {
> + preempt_enable_notrace();
> barrier();
> trace_recursion_clear(bit);
> }
The two comments should be updated too since Steven removed the "bit == 0"
trick.
> @@ -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.
Regards
Miroslav
next prev parent reply other threads:[~2021-10-26 9:36 UTC|newest]
Thread overview: 11+ 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 3:15 ` [PATCH v5 1/2] ftrace: disable preemption when recursion locked 王贇
2021-10-26 9:35 ` Miroslav Benes [this message]
2021-10-26 9:48 ` 王贇
2021-10-26 12:01 ` Steven Rostedt
2021-10-27 1:54 ` 王贇
2021-10-27 2:26 ` Steven Rostedt
2021-10-27 2:28 ` 王贇
2021-10-27 2:11 ` [PATCH v6] " 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
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