From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Jonathan Corbet <corbet@lwn.net>, Ingo Molnar <mingo@redhat.com>,
Shuah Khan <shuah@kernel.org>, Tom Zanussi <zanussi@kernel.org>,
Kalesh Singh <kaleshsingh@google.com>
Subject: [for-next][PATCH 11/14] tracing/histogram: Update division by 0 documentation
Date: Tue, 02 Nov 2021 16:11:37 -0400 [thread overview]
Message-ID: <20211102201158.577975229@goodmis.org> (raw)
In-Reply-To: 20211102201126.559641540@goodmis.org
From: Kalesh Singh <kaleshsingh@google.com>
If the divisor is a constant and zero, the undeifned case can be
detected and an error returned instead of -1.
Link: https://lkml.kernel.org/r/20211029183339.3216491-3-kaleshsingh@google.com
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
Documentation/trace/histogram.rst | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/Documentation/trace/histogram.rst b/Documentation/trace/histogram.rst
index 66ec972dfb78..859fd1b76c63 100644
--- a/Documentation/trace/histogram.rst
+++ b/Documentation/trace/histogram.rst
@@ -1766,7 +1766,8 @@ using the same key and variable from yet another event::
Expressions support the use of addition, subtraction, multiplication and
division operators (+-\*/).
-Note that division by zero always returns -1.
+Note if division by zero cannot be detected at parse time (i.e. the
+divisor is not a constant), the result will be -1.
Numeric constants can also be used directly in an expression::
--
2.33.0
next prev parent reply other threads:[~2021-11-02 20:12 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-02 20:11 [for-next][PATCH 00/14] tracing: Updates for 5.16 Steven Rostedt
2021-11-02 20:11 ` [for-next][PATCH 01/14] tracing/osnoise: Do not follow tracing_cpumask Steven Rostedt
2021-11-02 20:11 ` [for-next][PATCH 02/14] tracing/osnoise: Improve comments about barrier need for NMI callbacks Steven Rostedt
2021-11-02 20:11 ` [for-next][PATCH 03/14] tracing/osnoise: Split workload start from the tracer start Steven Rostedt
2021-11-02 20:11 ` [for-next][PATCH 04/14] tracing/osnoise: Use start/stop_per_cpu_kthreads() on osnoise_cpus_write() Steven Rostedt
2021-11-02 20:11 ` [for-next][PATCH 05/14] tracing/osnoise: Support a list of trace_array *tr Steven Rostedt
2021-11-02 20:11 ` [for-next][PATCH 06/14] tracing/osnoise: Remove TIMERLAT ifdefs from inside functions Steven Rostedt
2021-11-02 20:11 ` [for-next][PATCH 07/14] tracing/osnoise: Allow multiple instances of the same tracer Steven Rostedt
2021-11-02 20:11 ` [for-next][PATCH 08/14] tracing/osnoise: Remove STACKTRACE ifdefs from inside functions Steven Rostedt
2021-11-02 20:11 ` [for-next][PATCH 09/14] tracing/osnoise: Remove PREEMPT_RT " Steven Rostedt
2021-11-02 20:11 ` [for-next][PATCH 10/14] tracing/histogram: Optimize division by constants Steven Rostedt
2021-11-02 20:11 ` Steven Rostedt [this message]
2021-11-02 20:11 ` [for-next][PATCH 12/14] tracing/histogram: Document hist trigger variables Steven Rostedt
2021-11-02 20:11 ` [for-next][PATCH 13/14] tracing/selftests: Add tests for hist trigger expression parsing Steven Rostedt
2021-11-02 20:11 ` [for-next][PATCH 14/14] ftrace/samples: Add missing prototype for my_direct_func Steven Rostedt
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