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[v5,0/2] fix & prevent the missing preemption disabling

Message ID 3ca92dc9-ea04-ddc2-71cd-524bfa5a5721@linux.alibaba.com (mailing list archive)
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Series fix & prevent the missing preemption disabling | expand

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王贇 Oct. 26, 2021, 3:14 a.m. UTC 
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@linux.alibaba.com/
v2: https://lore.kernel.org/all/b1d7fe43-ce84-0ed7-32f7-ea1d12d0b716@linux.alibaba.com/
v3: https://lore.kernel.org/all/609b565a-ed6e-a1da-f025-166691b5d994@linux.alibaba.com/
V4: https://lore.kernel.org/all/32a36348-69ee-6464-390c-3a8d6e9d2b53@linux.alibaba.com/

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      | 11 ++++++++++-
 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, 25 insertions(+), 35 deletions(-)