From: Steven Rostedt <rostedt@goodmis.org>
To: Kalesh Singh <kaleshsingh@google.com>
Cc: surenb@google.com, hridya@google.com, namhyung@kernel.org,
Jonathan Corbet <corbet@lwn.net>, Ingo Molnar <mingo@redhat.com>,
Shuah Khan <shuah@kernel.org>, Tom Zanussi <zanussi@kernel.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-kselftest@vger.kernel.org
Subject: Re: [PATCH 2/5] tracing: Add division and multiplication support for hist triggers
Date: Tue, 19 Oct 2021 16:45:43 -0400 [thread overview]
Message-ID: <20211019164543.2ca20830@gandalf.local.home> (raw)
In-Reply-To: <20210915195306.612966-3-kaleshsingh@google.com>
On Wed, 15 Sep 2021 19:52:46 +0000
Kalesh Singh <kaleshsingh@google.com> wrote:
> +static u64 hist_field_div(struct hist_field *hist_field,
> + struct tracing_map_elt *elt,
> + struct trace_buffer *buffer,
> + struct ring_buffer_event *rbe,
> + void *event)
> +{
> + struct hist_field *operand1 = hist_field->operands[0];
> + struct hist_field *operand2 = hist_field->operands[1];
> +
> + u64 val1 = operand1->fn(operand1, elt, buffer, rbe, event);
> + u64 val2 = operand2->fn(operand2, elt, buffer, rbe, event);
> +
> + /* Return -1 for the undefined case */
> + if (!val2)
> + return -1;
> +
> + return val1 / val2;
This wont work on x86 32 bit machines, as u64 division will trigger
floating point arithmetic by the compiler, and cause a fault.
You'll need to use one of the div64() helpers.
-- Steve
> +}
> +
next prev parent reply other threads:[~2021-10-19 20:45 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-15 19:52 [PATCH 0/5] tracing: Extend histogram triggers expression parsing Kalesh Singh
2021-09-15 19:52 ` [PATCH 1/5] tracing: Add support for creating hist trigger variables from literal Kalesh Singh
2021-10-19 20:48 ` Steven Rostedt
2021-10-19 21:21 ` Kalesh Singh
2021-10-19 21:26 ` Steven Rostedt
2021-10-19 21:49 ` Kalesh Singh
2021-09-15 19:52 ` [PATCH 2/5] tracing: Add division and multiplication support for hist triggers Kalesh Singh
2021-10-19 20:45 ` Steven Rostedt [this message]
2021-10-19 21:24 ` Kalesh Singh
2021-09-15 19:52 ` [PATCH 3/5] tracing: Fix operator precedence for hist triggers expression Kalesh Singh
2021-09-15 19:52 ` [PATCH 4/5] tracing/selftests: Add tests for hist trigger expression parsing Kalesh Singh
2021-09-15 19:52 ` [PATCH 5/5] tracing/histogram: Document expression arithmetic and constants Kalesh Singh
2021-09-15 20:09 ` [PATCH 0/5] tracing: Extend histogram triggers expression parsing Kalesh Singh
2021-09-30 22:58 ` Namhyung Kim
2021-10-02 0:54 ` Kalesh Singh
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