tree c542bc412a1c1769616b3f857ac8cc396d0674b0
parent 3650b228f83adda7e5ee532e2b90429c03f7b9ec
author Zong Li <zong.li@sifive.com> 1603265919 +0800
committer Thomas Gleixner <tglx@linutronix.de> 1603710747 +0100

stop_machine, rcu: Mark functions as notrace

Some architectures assume that the stopped CPUs don't make function calls
to traceable functions when they are in the stopped state. See also commit
cb9d7fd51d9f ("watchdog: Mark watchdog touch functions as notrace").

Violating this assumption causes kernel crashes when switching tracer on
RISC-V.

Mark rcu_momentary_dyntick_idle() and stop_machine_yield() notrace to
prevent this.

Fixes: 4ecf0a43e729 ("processor: get rid of cpu_relax_yield")
Fixes: 366237e7b083 ("stop_machine: Provide RCU quiescent state in multi_cpu_stop()")
Signed-off-by: Zong Li <zong.li@sifive.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Atish Patra <atish.patra@wdc.com>
Tested-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20201021073839.43935-1-zong.li@sifive.com