Adding upstream version 2:4.17.12+dfsg.upstream/2%4.17.12+dfsgupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 218 insertions, 0 deletions

diff --git a/ctdb/config/debug_locks.sh b/ctdb/config/debug_locks.sh
new file mode 100755
index 0000000..6c730ee
--- /dev/null
+++ b/ctdb/config/debug_locks.sh
@@ -0,0 +1,218 @@
+#!/bin/sh
+
+# This script attempts to find processes holding locks on a particular
+# CTDB database and dumps a stack trace for each such processe.
+#
+# There are 2 cases:
+#
+# * Samba is configured to use fcntl locks
+#
+#   In this case /proc/locks is parsed to find potential lock holders
+#
+# * Samba is configured to use POSIX robust mutexes
+#
+#   In this case the helper program tdb_mutex_check is used to find
+#   potential lock holders.
+#
+#   This helper program uses a private glibc struct field, so is
+#   neither portable nor supported.  If this field is not available
+#   then the helper is not built.  Unexpected changes in internal
+#   glibc structures may cause unexpected results, including crashes.
+#   Bug reports for this helper program are not accepted without an
+#   accompanying patch.
+
+[ -n "$CTDB_BASE" ] || \
+	CTDB_BASE=$(d=$(dirname "$0") && cd -P "$d" && echo "$PWD")
+
+. "${CTDB_BASE}/functions"
+
+if [ $# -ne 4 ] ; then
+	die "usage: $0 <pid> { DB | RECORD } <tdb_path> { FCNTL | MUTEX }"
+fi
+
+lock_helper_pid="$1"
+# lock_scope is unused for now
+# shellcheck disable=SC2034
+lock_scope="$2"
+tdb_path="$3"
+lock_type="$4"
+
+# type is at least mentioned in POSIX and more is portable than which(1)
+# shellcheck disable=SC2039
+if ! type gstack >/dev/null 2>&1 ; then
+	gstack ()
+	{
+		_pid="$1"
+
+		gdb -batch --quiet -nx "/proc/${_pid}/exe" "$_pid" \
+		    -ex "thread apply all bt" 2>/dev/null |
+			grep '^\(#\|Thread \)'
+	}
+fi
+
+# Load/cache database options from configuration file
+ctdb_get_db_options
+
+dump_stack ()
+{
+	_pid="$1"
+
+	echo "----- Stack trace for PID=${_pid} -----"
+	_state=$(ps -p "$_pid" -o state= | cut -c 1)
+	if [ "$_state" = "D" ] ; then
+		# Don't run gstack on a process in D state since
+		# gstack will hang until the process exits D state.
+		# Although it is possible for a process to transition
+		# to D state after this check, it is unlikely because
+		# if a process is stuck in D state then it is probably
+		# the reason why this script was called.  Note that a
+		# kernel stack almost certainly won't help diagnose a
+		# deadlock... but it will probably give us someone to
+		# blame!
+		echo "----- Process in D state, printing kernel stack only"
+		get_proc "${_pid}/stack"
+	else
+		gstack "$_pid"
+	fi
+}
+
+dump_stacks ()
+{
+	_pids="$1"
+
+	# Use word splitting to squash whitespace
+	# shellcheck disable=SC2086
+	_pids=$(echo $_pids | tr ' ' '\n' | sort -u)
+
+	for _pid in $_pids; do
+		dump_stack "$_pid"
+	done
+}
+
+get_tdb_file_id ()
+{
+	if ! _device_inode=$(stat -c "%d:%i" "$tdb_path" 2>/dev/null) ; then
+		die "Unable to stat \"${tdb_path}\""
+	fi
+	_device="${_device_inode%%:*}"
+	_device_major=$((_device >> 8))
+	_device_minor=$((_device & 0xff))
+	_inode="${_device_inode#*:}"
+	printf '%02x:%02x:%u\n' "$_device_major" "$_device_minor" "$_inode"
+}
+
+debug_via_proc_locks ()
+{
+	# Get file ID to match relevant column in /proc/locks
+	_file_id=$(get_tdb_file_id)
+
+	# Log information from /proc/locks about the waiting process
+	_tdb=$(basename "$tdb_path")
+	_comm=$(ps -p "$lock_helper_pid" -o comm=)
+	_out=$(get_proc "locks" |
+	       awk -v pid="$lock_helper_pid" \
+		   -v file_id="$_file_id" \
+		   -v file="$_tdb" \
+		   -v comm="$_comm" \
+		   '$2 == "->" &&
+		    $3 == "POSIX" &&
+		    $4 == "ADVISORY" &&
+		    $5 == "WRITE" &&
+		    $6 == pid &&
+		    $7 == file_id { print $6, comm, file, $8, $9 }')
+	if [ -n "$_out" ] ; then
+		echo "Waiter:"
+		echo "$_out"
+	fi
+
+	# Parse /proc/locks and find process holding locks on $tdb_path
+	# extract following information
+	#    pid process_name tdb_name offsets
+	_out=$(get_proc "locks" |
+	       awk -v pid="$lock_helper_pid" \
+		   -v file_id="$_file_id" \
+		   -v file="$_tdb" \
+		   '$2 == "POSIX" &&
+		    $3 == "ADVISORY" &&
+		    $4 == "WRITE" &&
+		    $5 != pid &&
+		    $6 == file_id { print $5, file, $7, $8 }' |
+	       while read -r _pid _rest ; do
+		       _pname=$(ps -p "$_pid" -o comm=)
+		       echo "$_pid $_pname $_rest"
+	       done)
+
+	if [ -z "$_out" ]; then
+		return
+	fi
+
+	# Log information about locks
+	echo "Lock holders:"
+	echo "$_out"
+
+	_pids=$(echo "$_out" | awk '{ print $1 }')
+
+	lock_holder_pids="${lock_holder_pids:+${lock_holder_pids} }${_pids}"
+}
+
+debug_via_tdb_mutex ()
+{
+	_helper="${CTDB_HELPER_BINDIR}/tdb_mutex_check"
+	if [ ! -x "$_helper" ] ; then
+		# Mutex helper not available - not supported?
+		# Avoid not found error...
+		return
+	fi
+
+	# Helper should always succeed
+	if ! _t=$("$_helper" "$tdb_path") ; then
+		return
+	fi
+
+	_out=$(echo "$_t" | sed -n -e 's#^\[\(.*\)\] pid=\(.*\)#\2 \1#p')
+
+	if [ -z "$_out" ]; then
+		if [ -n "$_t" ] ; then
+			echo "$_t" | grep -F 'trylock failed'
+		fi
+		return
+	fi
+
+	# Get process names, append $tdb_path
+	_out=$(echo "$_out" |
+	       while read -r _pid _rest ; do
+		       _pname=$(ps -p "$_pid" -o comm=)
+		       _tdb=$(basename "$tdb_path")
+		       echo "${_pid} ${_pname} ${_tdb} ${_rest}"
+	       done)
+
+	# Log information about locks
+	echo "Lock holders:"
+	echo "$_out"
+
+	# Get PIDs of processes that are holding locks
+	_pids=$(echo "$_out" |
+		awk -v pid="$lock_helper_pid" '$1 != pid {print $1}')
+
+	lock_holder_pids="${lock_holder_pids:+${lock_holder_pids} }${_pids}"
+}
+
+(
+	flock -n 9 || exit 1
+
+	echo "===== Start of debug locks PID=$$ ====="
+
+	lock_holder_pids=""
+
+	debug_via_proc_locks
+
+	if [ "$lock_type" = "MUTEX" ] ; then
+		debug_via_tdb_mutex
+	fi
+
+	dump_stacks "$lock_holder_pids"
+
+	echo "===== End of debug locks PID=$$ ====="
+)9>"${CTDB_SCRIPT_VARDIR}/debug_locks.lock" | script_log "ctdbd-lock"
+
+exit 0