[PATCH 0/3] Kill off show_stack() NULL-implies-current idiom

From: Mark Rutland
Date: Mon Sep 26 2016 - 11:16:28 EST

Today, show_stack() accepts a NULL task parameter, which it takes to mean the
current task. However, as noted in tip/x86/asm commit:

81539169f283329f ("x86/dumpstack: Remove NULL task pointer convention")

... having a NULL task parameter imply current leads to subtle bugs in stack
walking code (so far seen on both 86 and arm64), makes callsites harder to
read, and is unnecessary as all callers have access to current.

As a step towards removing the problematic NULL-implies-current idiom entirely,
these patches ensure that generic code explictly passes current to
show_stack(), rather than relying on arch code to handle NULL.


Mark Rutland (3):
sched: document that show_stack() should not be passed a NULL task
drivers/tty: Explicitly pass current to show_stack
lib: dump_stack: explicitly pass current to show_stack

drivers/tty/sysrq.c | 2 +-
include/linux/sched.h | 3 +++
lib/dump_stack.c | 2 +-
3 files changed, 5 insertions(+), 2 deletions(-)