The testing show that perf_ftrace_function_call() are using smp_processor_id()
with preemption enabled, all the checking on CPU could be wrong after preemption.
As Peter point out, the section between ftrace_test_recursion_trylock/unlock()
pair require the preemption to be disabled as 'Documentation/trace/ftrace-uses.rst'
explained, but currently the work is done outside of the helpers.
Patch 1/2 will make sure preemption disabled after trylock() succeed,
patch 2/2 will do smp_processor_id() checking after trylock to address the
issue.
v1: https://lore.kernel.org/all/[email protected]/
v2: https://lore.kernel.org/all/[email protected]/
Michael Wang (2):
ftrace: disable preemption between ftrace_test_recursion_trylock/unlock()
ftrace: do CPU checking after preemption disabled
arch/csky/kernel/probes/ftrace.c | 2 --
arch/parisc/kernel/ftrace.c | 2 --
arch/powerpc/kernel/kprobes-ftrace.c | 2 --
arch/riscv/kernel/probes/ftrace.c | 2 --
arch/x86/kernel/kprobes/ftrace.c | 2 --
include/linux/trace_recursion.h | 17 ++++++++++++++++-
kernel/livepatch/patch.c | 13 +++++++------
kernel/trace/trace_event_perf.c | 6 +++---
kernel/trace/trace_functions.c | 5 -----
9 files changed, 26 insertions(+), 25 deletions(-)
--
1.8.3.1