Just a ping, to see if there are any more comments :-P Regards, Michael Wang On 2021/10/18 上午11:38, 王贇 wrote: > 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. > > And since the internal using of trace_test_and_set_recursion() > and trace_clear_recursion() also require preemption to be disabled, we > can just merge the logical together. > > Patch 1/2 will make sure preemption disabled when recursion lock succeed, > patch 2/2 will do smp_processor_id() checking after trylock() to address the > issue. > > v1: https://lore.kernel.org/all/8c7de46d-9869-aa5e-2bb9-5dbc2eda395e@xxxxxxxxxxxxxxxxx/ > v2: https://lore.kernel.org/all/b1d7fe43-ce84-0ed7-32f7-ea1d12d0b716@xxxxxxxxxxxxxxxxx/ > v3: https://lore.kernel.org/all/609b565a-ed6e-a1da-f025-166691b5d994@xxxxxxxxxxxxxxxxx/ > > Michael Wang (2): > ftrace: disable preemption when recursion locked > 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 | 20 +++++++++++++++++++- > kernel/livepatch/patch.c | 13 +++++++------ > kernel/trace/ftrace.c | 15 +++++---------- > kernel/trace/trace_event_perf.c | 6 +++--- > kernel/trace/trace_functions.c | 5 ----- > 10 files changed, 34 insertions(+), 35 deletions(-) >
