[PATCH 08/13] scripts/gdb: Add helper and convenience function to look up tasks

[Jan Kiszka]

Add the helper task_by_pid that can look up a task by its PID. Also
export it as a convenience function.

Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
---
 scripts/gdb/task.py        |   29 +++++++++++++++++++++++++++++
 scripts/gdb/vmlinux-gdb.py |    1 +
 2 files changed, 30 insertions(+), 0 deletions(-)

diff --git a/scripts/gdb/task.py b/scripts/gdb/task.py
index 1e4f61e..41d85cc 100644
--- a/scripts/gdb/task.py
+++ b/scripts/gdb/task.py
@@ -38,3 +38,32 @@ def for_each_task(func, arg = None):
 					 get_task_ptr_type(), "thread_group")
 			if t == g:
 				break
+
+def get_task_by_pid(pid):
+	def match_pid(t, arg):
+		if int(t['pid']) == arg['pid']:
+			arg['task'] = t
+
+	arg = { 'pid': pid, 'task': None }
+	for_each_task(match_pid, arg)
+
+	return arg['task']
+
+
+class LxTaskByPidFunc(gdb.Function):
+	__doc__ = "Find Linux task by PID and return the task_struct variable.\n" \
+		  "\n" \
+		  "$lx_task_by_pid(PID): Given PID, iterate over all tasks of the target and\n" \
+		  "return that task_struct variable which PID matches.\n"
+
+	def __init__(self):
+		super(LxTaskByPidFunc, self).__init__("lx_task_by_pid")
+
+	def invoke(self, pid):
+		task = get_task_by_pid(pid)
+		if task:
+			return task.dereference()
+		else:
+			raise gdb.GdbError("No task of PID " + str(pid))
+
+LxTaskByPidFunc()
diff --git a/scripts/gdb/vmlinux-gdb.py b/scripts/gdb/vmlinux-gdb.py
index 8b0422e..deaf652 100644
--- a/scripts/gdb/vmlinux-gdb.py
+++ b/scripts/gdb/vmlinux-gdb.py
@@ -22,3 +22,4 @@ else:
 	import utils
 	import symbols
 	import dmesg
+	import task
-- 
1.7.3.4

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