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authorHeiko Carstens <heiko.carstens@de.ibm.com>2016-11-03 15:09:24 +0300
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2016-11-08 12:29:44 +0300
commit7f8d61f005228fc48e6e2ca3c9af3302cd4870af (patch)
treef3eb2f26a65bf6c212819af6cd3aa9215d3078a1
parent237d6e6884136923b6bd26d5141ebe1d065960c9 (diff)
downloadlinux-7f8d61f005228fc48e6e2ca3c9af3302cd4870af.tar.xz
percpu: use notrace variant of preempt_disable/preempt_enable
Commit 345ddcc882d8 ("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: 345ddcc882d8 ("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>
-rw-r--r--include/asm-generic/percpu.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/include/asm-generic/percpu.h b/include/asm-generic/percpu.h
index 40e887068da2..0504ef8f3aa3 100644
--- a/include/asm-generic/percpu.h
+++ b/include/asm-generic/percpu.h
@@ -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; \
})