From e4f387d8db3ba3c2dae4d8bdfe7bb5f4fe1bcb0d 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 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 CC: stable@kernel.org [v2.6.32+] Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/platforms/pseries/hvCall_inst.c | 4 +--- arch/powerpc/platforms/pseries/lpar.c | 2 ++ 2 files changed, 3 insertions(+), 3 deletions(-) (limited to 'arch/powerpc') diff --git a/arch/powerpc/platforms/pseries/hvCall_inst.c b/arch/powerpc/platforms/pseries/hvCall_inst.c index f106662f438..c9311cfdfca 100644 --- a/arch/powerpc/platforms/pseries/hvCall_inst.c +++ b/arch/powerpc/platforms/pseries/hvCall_inst.c @@ -109,7 +109,7 @@ static void probe_hcall_entry(void *ignored, unsigned long opcode, unsigned long if (opcode > MAX_HCALL_OPCODE) return; - h = &get_cpu_var(hcall_stats)[opcode / 4]; + h = &__get_cpu_var(hcall_stats)[opcode / 4]; h->tb_start = mftb(); h->purr_start = mfspr(SPRN_PURR); } @@ -126,8 +126,6 @@ static void probe_hcall_exit(void *ignored, unsigned long opcode, unsigned long h->num_calls++; h->tb_total += mftb() - h->tb_start; h->purr_total += mfspr(SPRN_PURR) - h->purr_start; - - put_cpu_var(hcall_stats); } static int __init hcall_inst_init(void) diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c index 27a49508b41..dc36ea6c772 100644 --- a/arch/powerpc/platforms/pseries/lpar.c +++ b/arch/powerpc/platforms/pseries/lpar.c @@ -554,6 +554,7 @@ void __trace_hcall_entry(unsigned long opcode, unsigned long *args) goto out; (*depth)++; + preempt_disable(); trace_hcall_entry(opcode, args); (*depth)--; @@ -576,6 +577,7 @@ void __trace_hcall_exit(long opcode, unsigned long retval, (*depth)++; trace_hcall_exit(opcode, retval, retbuf); + preempt_enable(); (*depth)--; out: -- cgit v1.2.3