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Date: Wed, 26 Feb 2025 11:11:56 -0500
From: Steven Rostedt <rostedt@goodmis.org>
To: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Mark
 Rutland <mark.rutland@arm.com>, Mathieu Desnoyers
 <mathieu.desnoyers@efficios.com>, Andrew Morton
 <akpm@linux-foundation.org>, Sven Schnelle <svens@linux.ibm.com>, Paul
 Walmsley <paul.walmsley@sifive.com>, Palmer Dabbelt <palmer@dabbelt.com>,
 Albert Ou <aou@eecs.berkeley.edu>, Guo Ren <guoren@kernel.org>, Donglin
 Peng <dolinux.peng@gmail.com>, Zheng Yejian <zhengyejian@huaweicloud.com>,
 bpf@vger.kernel.org
Subject: Re: [PATCH v3 2/4] ftrace: Add support for function argument to
 graph tracer
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On Wed, 26 Feb 2025 23:48:52 +0900
Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote:

> > -	event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_ENT,
> > -					  sizeof(*entry), trace_ctx);
> > +	/* If fregs is defined, add FTRACE_REGS_MAX_ARGS long size words */
> > +	size = sizeof(*entry) + (FTRACE_REGS_MAX_ARGS * !!fregs * sizeof(long));  
> 
> Is `!!fregs` always 1 if fregs != NULL? (seems to depend on compiler)

Yes, C guarantees that ! is either 1 or zero. If you want to convert
something from non zero to 1, the C convention is "!!".

> 
> Others looks good to me.
> 
> Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>


Thanks!

-- Steve