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| author | Lai Jiangshan <laijs@cn.fujitsu.com> | 2009-03-18 16:42:57 +0800 |
|---|---|---|
| committer | Steven Rostedt <srostedt@redhat.com> | 2009-03-18 20:36:59 -0400 |
| commit | e9d9df44736d116726f4596f7e2f9ce2764ffc0a (patch) | |
| tree | bca129639885fa7288b925e5053f3787fa7e625a /kernel/trace/trace_functions_graph.c | |
| parent | 4acd4d00f716873e27e7b60ae292cbdbfae674dd (diff) | |
ftrace: protect running nmi (V3)
When I review the sensitive code ftrace_nmi_enter(), I found
the atomic variable nmi_running does protect NMI VS do_ftrace_mod_code(),
but it can not protects NMI(entered nmi) VS NMI(ftrace_nmi_enter()).
cpu#1 | cpu#2 | cpu#3
ftrace_nmi_enter() | do_ftrace_mod_code() |
not modify | |
------------------------|-----------------------|--
executing | set mod_code_write = 1|
executing --|-----------------------|--------------------
executing | | ftrace_nmi_enter()
executing | | do modify
------------------------|-----------------------|-----------------
ftrace_nmi_exit() | |
cpu#3 may be being modified the code which is still being executed on cpu#1,
it will have undefined results and possibly take a GPF, this patch
prevents it occurred.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
LKML-Reference: <49C0B411.30003@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Diffstat (limited to 'kernel/trace/trace_functions_graph.c')
0 files changed, 0 insertions, 0 deletions