[PATCH] tools: rcu: Added check for argument and usage function

[Bhaskar Chowdhury <unixbhaskar@gmail.com>]

Inducted some argument check as well put the important information in a
function for better usecase.

cc: paulmck@kernel.org

Signed-off-by: Bhaskar Chowdhury <unixbhaskar@gmail.com>
---
  Paul, pardon my brevity. Chances might be there that I might have
  misunderstood the requirement.
 tools/rcu/extract-stall.sh | 28 ++++++++++++++++++++++------
 1 file changed, 22 insertions(+), 6 deletions(-)

diff --git a/tools/rcu/extract-stall.sh b/tools/rcu/extract-stall.sh
index e565697c9f90..d71617d0e565 100644
--- a/tools/rcu/extract-stall.sh
+++ b/tools/rcu/extract-stall.sh
@@ -1,11 +1,27 @@
 #!/bin/sh
 # SPDX-License-Identifier: GPL-2.0+
-#
-# Extract any RCU CPU stall warnings present in specified file.
-# Filter out clocksource lines.  Note that preceding-lines excludes the
-# initial line of the stall warning but trailing-lines includes it.
-#
-# Usage: extract-stall.sh dmesg-file [ preceding-lines [ trailing-lines ] ]
+
+# Terminate the script, if the argument file is missing
+
+if [[ $# -eq 0 ]];then
+
+	echo You are suppose to pass the dmesg file as an argument.
+	usage
+	exit 1
+fi
+
+# This is an usage function to spit out information about properly use this
+# script
+
+usage() {
+
+      echo Extract any RCU CPU stall warnings present in specified file.
+      echo Filter out clocksource lines.  Note that preceding-lines excludes
+      echo The initial line of the stall warning but trailing-lines includes it.
+
+      echo $0 dmesg-file [ preceding-lines [ trailing-lines  ]  ]
+
+}

 echo $1
 preceding_lines="${2-3}"
--
2.38.1