scripts/gdb/tasks: fix lx-ps command error

Since commit 8e1f385104ac ("kill task_struct->thread_group") remove
the thread_group, we will encounter below issue.

(gdb) lx-ps
      TASK          PID    COMM
0xffff800086503340   0   swapper/0
Python Exception <class 'gdb.error'>: There is no member named thread_group.
Error occurred in Python: There is no member named thread_group.

We use signal->thread_head to iterate all threads instead.

[[email protected]: v2]
  Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 8e1f385104ac ("kill task_struct->thread_group")
Signed-off-by: Kuan-Ying Lee <[email protected]>
Acked-by: Oleg Nesterov <[email protected]>
Tested-by: Florian Fainelli <[email protected]>
Cc: AngeloGioacchino Del Regno <[email protected]>
Cc: Chinwen Chang <[email protected]>
Cc: Kuan-Ying Lee <[email protected]>
Cc: Matthias Brugger <[email protected]>
Cc: Qun-Wei Lin <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions