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percpu: use notrace variant of preempt_disable/preempt_enable

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Commit 345ddcc882 ("ftrace: Have set_ftrace_pid use the bitmap like
events do") added a couple of this_cpu_read calls to the ftrace code.

On x86 this is not a problem, since it has single instructions to read
percpu data. Other architectures which use the generic variant now
have additional preempt_disable and preempt_enable calls in the core
ftrace code. This may lead to recursive calls and in result to a dead
machine, e.g. if preemption and debugging options are enabled.

To fix this use the notrace variant of preempt_disable and
preempt_enable within the generic percpu code.

Reported-and-bisected-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Tested-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Fixes: 345ddcc882 ("ftrace: Have set_ftrace_pid use the bitmap like events do")
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Heiko Carstens 2016-11-03 13:09:24 +01:00 committed by Martin Schwidefsky
parent 237d6e6884
commit 7f8d61f005
1 changed files with 2 additions and 2 deletions
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4
include/asm-generic/percpu.h
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@ -118,9 +118,9 @@ do { \
#define this_cpu_generic_read(pcp) \
({ \
typeof(pcp) __ret; \
preempt_disable(); \
preempt_disable_notrace(); \
__ret = raw_cpu_generic_read(pcp); \
preempt_enable(); \
preempt_enable_notrace(); \
__ret; \
})