From 310454827ddacece376b50c99e537da88c577a31 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sun, 4 Sep 2011 12:18:00 -0700 Subject: [PATCH] powerpc: Work around tracing from dyntick-idle mode PowerPC LPAR's __trace_hcall_exit() can invoke event tracing at a point where RCU has been told that the CPU is in dyntick-idle mode. Because event tracing uses RCU, this can result in failures. A correct fix would arrange for RCU to be told about dyntick-idle mode after tracing had completed, however, this will require some care because it appears that __trace_hcall_exit() can also be called from non-dyntick-idle mode. Signed-off-by: Paul E. McKenney Cc: anton@samba.org Cc: benh@kernel.crashing.org Cc: paulus@samba.org --- arch/powerpc/platforms/pseries/lpar.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c index 39e6e0a7b2fa..668f30060b9f 100644 --- a/arch/powerpc/platforms/pseries/lpar.c +++ b/arch/powerpc/platforms/pseries/lpar.c @@ -715,12 +715,14 @@ EXPORT_SYMBOL(arch_free_page); /* NB: reg/unreg are called while guarded with the tracepoints_mutex */ extern long hcall_tracepoint_refcount; +#if 0 /* work around buggy use of RCU from dyntick-idle mode */ /* * Since the tracing code might execute hcalls we need to guard against * recursion. One example of this are spinlocks calling H_YIELD on * shared processor partitions. */ static DEFINE_PER_CPU(unsigned int, hcall_trace_depth); +#endif /* #if 0 work around buggy use of RCU from dyntick-idle mode */ void hcall_tracepoint_regfunc(void) { @@ -734,6 +736,7 @@ void hcall_tracepoint_unregfunc(void) void __trace_hcall_entry(unsigned long opcode, unsigned long *args) { +#if 0 /* work around buggy use of RCU from dyntick-idle mode */ unsigned long flags; unsigned int *depth; @@ -750,11 +753,13 @@ void __trace_hcall_entry(unsigned long opcode, unsigned long *args) out: local_irq_restore(flags); +#endif /* #if 0 work around buggy use of RCU from dyntick-idle mode */ } void __trace_hcall_exit(long opcode, unsigned long retval, unsigned long *retbuf) { +#if 0 /* work around buggy use of RCU from dyntick-idle mode */ unsigned long flags; unsigned int *depth; @@ -771,6 +776,7 @@ void __trace_hcall_exit(long opcode, unsigned long retval, out: local_irq_restore(flags); +#endif /* #if 0 work around buggy use of RCU from dyntick-idle mode */ } #endif -- 2.39.5