From ec0d3233562d591c892841fcfa73edd3700a6ca6 Mon Sep 17 00:00:00 2001 From: Li Zhong Date: Sun, 18 Dec 2011 16:03:04 +0000 Subject: powerpc: Fix unpaired probe_hcall_entry and probe_hcall_exit commit e4f387d8db3ba3c2dae4d8bdfe7bb5f4fe1bcb0d upstream. Unpaired calling of probe_hcall_entry and probe_hcall_exit might happen as following, which could cause incorrect preempt count. __trace_hcall_entry => trace_hcall_entry -> probe_hcall_entry => get_cpu_var => preempt_disable __trace_hcall_exit => trace_hcall_exit -> probe_hcall_exit => put_cpu_var => preempt_enable where: A => B and A -> B means A calls B, but => means A will call B through function name, and B will definitely be called. -> means A will call B through function pointer, so B might not be called if the function pointer is not set. So error happens when only one of probe_hcall_entry and probe_hcall_exit get called during a hcall. This patch tries to move the preempt count operations from probe_hcall_entry and probe_hcall_exit to its callers. Reported-by: Paul E. McKenney Signed-off-by: Li Zhong Tested-by: Paul E. McKenney Signed-off-by: Benjamin Herrenschmidt Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/platforms/pseries/lpar.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/powerpc/platforms/pseries/lpar.c') diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c index ed96b37..81e30d9 100644 --- a/arch/powerpc/platforms/pseries/lpar.c +++ b/arch/powerpc/platforms/pseries/lpar.c @@ -745,6 +745,7 @@ void __trace_hcall_entry(unsigned long opcode, unsigned long *args) goto out; (*depth)++; + preempt_disable(); trace_hcall_entry(opcode, args); (*depth)--; @@ -767,6 +768,7 @@ void __trace_hcall_exit(long opcode, unsigned long retval, (*depth)++; trace_hcall_exit(opcode, retval, retbuf); + preempt_enable(); (*depth)--; out: -- cgit v1.1