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authorLi Zhong <zhong@linux.vnet.ibm.com>2011-12-18 16:03:04 +0000
committerGreg Kroah-Hartman <gregkh@suse.de>2012-01-12 11:29:23 -0800
commitddcf85d72ffe4fd46239a94253fe04c114d4d1e2 (patch)
treee4da65c4289f3d529ac4c6e1f752e6dbbd1ebfd8
parent8e04782a06882913304916bc60960e4fc7405e18 (diff)
downloadvexpress-lsk-ddcf85d72ffe4fd46239a94253fe04c114d4d1e2.tar.gz
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 <paulmck@linux.vnet.ibm.com> Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com> Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--arch/powerpc/platforms/pseries/hvCall_inst.c4
-rw-r--r--arch/powerpc/platforms/pseries/lpar.c2
2 files changed, 3 insertions, 3 deletions
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: