cppcheck: integrete cppcheck

In order for cppcheck to perform a proper analysis it needs to be
aware of how the sources are compiled (source files, include
paths/files, extra defines, etc).  All the needed information is
available from the Makefiles and can be leveraged with a generic
cppcheck Makefile target.  So let's add one.

Additional minor changes:

* Removing the cppcheck-suppressions.txt file.  With cppcheck 2.3
  and these changes it appears to no longer be needed.  Some inline
  suppressions were also removed since they appear not to be
  needed.  We can add them back if it turns out they're needed
  for older versions of cppcheck.

* Added the ax_count_cpus m4 macro to detect at configure time how
  many processors are available in order to run multiple cppcheck
  jobs.  This value is also now used as a replacement for nproc
  when executing the kernel interface checks.

* "PHONY =" line moved in to the Rules.am file which is included
  at the top of all Makefile.am's.  This is just convenient becase
  it allows us to use the += syntax to add phony targets.

* One upside of this integration worth mentioning is it now allows
  `make cppcheck` to be run in any directory to check that subtree.

* For the moment, cppcheck is not run against the FreeBSD specific
  kernel sources.  The cppcheck-FreeBSD target will need to be
  implemented and testing on FreeBSD to support this.

Reviewed-by: Ryan Moeller <ryan@ixsystems.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #11508

config/CppCheck.am

@@ -0,0 +1,11 @@
+#
+# Default rules for running cppcheck against the the user space components.
+#
+
+PHONY += cppcheck
+
+CPPCHECKFLAGS  = --std=c99 --quiet --max-configs=1 --error-exitcode=2
+CPPCHECKFLAGS += --inline-suppr -U_KERNEL
+
+cppcheck:
+	$(CPPCHECK) -j$(CPU_COUNT) $(CPPCHECKFLAGS) $(DEFAULT_INCLUDES) $(SOURCES)

config/Rules.am

@@ -3,6 +3,7 @@
 # should include these rules and override or extend them as needed.
 #
 
+PHONY =
 DEFAULT_INCLUDES = \
 	-include $(top_builddir)/zfs_config.h \
 	-I$(top_builddir)/include \

config/always-cppcheck.m4

@@ -0,0 +1,6 @@
+dnl #
+dnl # Check if cppcheck is available.
+dnl #
+AC_DEFUN([ZFS_AC_CONFIG_ALWAYS_CPPCHECK], [
+	AC_CHECK_PROG([CPPCHECK], [cppcheck], [cppcheck])
+])

config/ax_count_cpus.m4

@@ -0,0 +1,101 @@
+# ===========================================================================
+#      https://www.gnu.org/software/autoconf-archive/ax_count_cpus.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_COUNT_CPUS([ACTION-IF-DETECTED],[ACTION-IF-NOT-DETECTED])
+#
+# DESCRIPTION
+#
+#   Attempt to count the number of logical processor cores (including
+#   virtual and HT cores) currently available to use on the machine and
+#   place detected value in CPU_COUNT variable.
+#
+#   On successful detection, ACTION-IF-DETECTED is executed if present. If
+#   the detection fails, then ACTION-IF-NOT-DETECTED is triggered. The
+#   default ACTION-IF-NOT-DETECTED is to set CPU_COUNT to 1.
+#
+# LICENSE
+#
+#   Copyright (c) 2014,2016 Karlson2k (Evgeny Grin) <k2k@narod.ru>
+#   Copyright (c) 2012 Brian Aker <brian@tangent.org>
+#   Copyright (c) 2008 Michael Paul Bailey <jinxidoru@byu.net>
+#   Copyright (c) 2008 Christophe Tournayre <turn3r@users.sourceforge.net>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved. This file is offered as-is, without any
+#   warranty.
+
+#serial 22
+
+  AC_DEFUN([AX_COUNT_CPUS],[dnl
+      AC_REQUIRE([AC_CANONICAL_HOST])dnl
+      AC_REQUIRE([AC_PROG_EGREP])dnl
+      AC_MSG_CHECKING([the number of available CPUs])
+      CPU_COUNT="0"
+
+      # Try generic methods
+
+      # 'getconf' is POSIX utility, but '_NPROCESSORS_ONLN' and
+      # 'NPROCESSORS_ONLN' are platform-specific
+      command -v getconf >/dev/null 2>&1 && \
+        CPU_COUNT=`getconf _NPROCESSORS_ONLN 2>/dev/null || getconf NPROCESSORS_ONLN 2>/dev/null` || CPU_COUNT="0"
+      AS_IF([[test "$CPU_COUNT" -gt "0" 2>/dev/null || ! command -v nproc >/dev/null 2>&1]],[[: # empty]],[dnl
+        # 'nproc' is part of GNU Coreutils and is widely available
+        CPU_COUNT=`OMP_NUM_THREADS='' nproc 2>/dev/null` || CPU_COUNT=`nproc 2>/dev/null` || CPU_COUNT="0"
+      ])dnl
+
+      AS_IF([[test "$CPU_COUNT" -gt "0" 2>/dev/null]],[[: # empty]],[dnl
+        # Try platform-specific preferred methods
+        AS_CASE([[$host_os]],dnl
+          [[*linux*]],[[CPU_COUNT=`lscpu -p 2>/dev/null | $EGREP -e '^@<:@0-9@:>@+,' -c` || CPU_COUNT="0"]],dnl
+          [[*darwin*]],[[CPU_COUNT=`sysctl -n hw.logicalcpu 2>/dev/null` || CPU_COUNT="0"]],dnl
+          [[freebsd*]],[[command -v sysctl >/dev/null 2>&1 && CPU_COUNT=`sysctl -n kern.smp.cpus 2>/dev/null` || CPU_COUNT="0"]],dnl
+          [[netbsd*]], [[command -v sysctl >/dev/null 2>&1 && CPU_COUNT=`sysctl -n hw.ncpuonline 2>/dev/null` || CPU_COUNT="0"]],dnl
+          [[solaris*]],[[command -v psrinfo >/dev/null 2>&1 && CPU_COUNT=`psrinfo 2>/dev/null | $EGREP -e '^@<:@0-9@:>@.*on-line' -c 2>/dev/null` || CPU_COUNT="0"]],dnl
+          [[mingw*]],[[CPU_COUNT=`ls -qpU1 /proc/registry/HKEY_LOCAL_MACHINE/HARDWARE/DESCRIPTION/System/CentralProcessor/ 2>/dev/null | $EGREP -e '^@<:@0-9@:>@+/' -c` || CPU_COUNT="0"]],dnl
+          [[msys*]],[[CPU_COUNT=`ls -qpU1 /proc/registry/HKEY_LOCAL_MACHINE/HARDWARE/DESCRIPTION/System/CentralProcessor/ 2>/dev/null | $EGREP -e '^@<:@0-9@:>@+/' -c` || CPU_COUNT="0"]],dnl
+          [[cygwin*]],[[CPU_COUNT=`ls -qpU1 /proc/registry/HKEY_LOCAL_MACHINE/HARDWARE/DESCRIPTION/System/CentralProcessor/ 2>/dev/null | $EGREP -e '^@<:@0-9@:>@+/' -c` || CPU_COUNT="0"]]dnl
+        )dnl
+      ])dnl
+
+      AS_IF([[test "$CPU_COUNT" -gt "0" 2>/dev/null || ! command -v sysctl >/dev/null 2>&1]],[[: # empty]],[dnl
+        # Try less preferred generic method
+        # 'hw.ncpu' exist on many platforms, but not on GNU/Linux
+        CPU_COUNT=`sysctl -n hw.ncpu 2>/dev/null` || CPU_COUNT="0"
+      ])dnl
+
+      AS_IF([[test "$CPU_COUNT" -gt "0" 2>/dev/null]],[[: # empty]],[dnl
+      # Try platform-specific fallback methods
+      # They can be less accurate and slower then preferred methods
+        AS_CASE([[$host_os]],dnl
+          [[*linux*]],[[CPU_COUNT=`$EGREP -e '^processor' -c /proc/cpuinfo 2>/dev/null` || CPU_COUNT="0"]],dnl
+          [[*darwin*]],[[CPU_COUNT=`system_profiler SPHardwareDataType 2>/dev/null | $EGREP -i -e 'number of cores:'|cut -d : -f 2 -s|tr -d ' '` || CPU_COUNT="0"]],dnl
+          [[freebsd*]],[[CPU_COUNT=`dmesg 2>/dev/null| $EGREP -e '^cpu@<:@0-9@:>@+: '|sort -u|$EGREP -e '^' -c` || CPU_COUNT="0"]],dnl
+          [[netbsd*]], [[CPU_COUNT=`command -v cpuctl >/dev/null 2>&1 && cpuctl list 2>/dev/null| $EGREP -e '^@<:@0-9@:>@+ .* online ' -c` || \
+                           CPU_COUNT=`dmesg 2>/dev/null| $EGREP -e '^cpu@<:@0-9@:>@+ at'|sort -u|$EGREP -e '^' -c` || CPU_COUNT="0"]],dnl
+          [[solaris*]],[[command -v kstat >/dev/null 2>&1 && CPU_COUNT=`kstat -m cpu_info -s state -p 2>/dev/null | $EGREP -c -e 'on-line'` || \
+                           CPU_COUNT=`kstat -m cpu_info 2>/dev/null | $EGREP -c -e 'module: cpu_info'` || CPU_COUNT="0"]],dnl
+          [[mingw*]],[AS_IF([[CPU_COUNT=`reg query 'HKLM\\Hardware\\Description\\System\\CentralProcessor' 2>/dev/null | $EGREP -e '\\\\@<:@0-9@:>@+$' -c`]],dnl
+                        [[: # empty]],[[test "$NUMBER_OF_PROCESSORS" -gt "0" 2>/dev/null && CPU_COUNT="$NUMBER_OF_PROCESSORS"]])],dnl
+          [[msys*]],[[test "$NUMBER_OF_PROCESSORS" -gt "0" 2>/dev/null && CPU_COUNT="$NUMBER_OF_PROCESSORS"]],dnl
+          [[cygwin*]],[[test "$NUMBER_OF_PROCESSORS" -gt "0" 2>/dev/null && CPU_COUNT="$NUMBER_OF_PROCESSORS"]]dnl
+        )dnl
+      ])dnl
+
+      AS_IF([[test "x$CPU_COUNT" != "x0" && test "$CPU_COUNT" -gt 0 2>/dev/null]],[dnl
+          AC_MSG_RESULT([[$CPU_COUNT]])
+          m4_ifvaln([$1],[$1],)dnl
+        ],[dnl
+          m4_ifval([$2],[dnl
+            AS_UNSET([[CPU_COUNT]])
+            AC_MSG_RESULT([[unable to detect]])
+            $2
+          ], [dnl
+            CPU_COUNT="1"
+            AC_MSG_RESULT([[unable to detect (assuming 1)]])
+          ])dnl
+        ])dnl
+      ])dnl

config/zfs-build.m4

@@ -153,6 +153,9 @@ AC_DEFUN([ZFS_AC_DEBUG_KMEM_TRACKING], [
 ])
 
 AC_DEFUN([ZFS_AC_CONFIG_ALWAYS], [
+	AX_COUNT_CPUS([])
+	AC_SUBST(CPU_COUNT)
+
 	ZFS_AC_CONFIG_ALWAYS_CC_NO_UNUSED_BUT_SET_VARIABLE
 	ZFS_AC_CONFIG_ALWAYS_CC_NO_BOOL_COMPARE
 	ZFS_AC_CONFIG_ALWAYS_CC_FRAME_LARGER_THAN
@@ -167,6 +170,7 @@ AC_DEFUN([ZFS_AC_CONFIG_ALWAYS], [
 	ZFS_AC_CONFIG_ALWAYS_PYTHON
 	ZFS_AC_CONFIG_ALWAYS_PYZFS
 	ZFS_AC_CONFIG_ALWAYS_SED
+	ZFS_AC_CONFIG_ALWAYS_CPPCHECK
 ])
 
 AC_DEFUN([ZFS_AC_CONFIG], [
@@ -191,12 +195,10 @@ AC_DEFUN([ZFS_AC_CONFIG], [
 
 	ZFS_AC_CONFIG_ALWAYS
 
-
 	AM_COND_IF([BUILD_LINUX], [
-		AC_ARG_VAR([TEST_JOBS],
-		    [simultaneous jobs during configure (defaults to $(nproc))])
+		AC_ARG_VAR([TEST_JOBS], [simultaneous jobs during configure])
 		if test "x$ac_cv_env_TEST_JOBS_set" != "xset"; then
-			TEST_JOBS=$(nproc)
+			TEST_JOBS=$CPU_COUNT
 		fi
 		AC_SUBST(TEST_JOBS)
 	])