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| author | Li Zhong <zhong@linux.vnet.ibm.com> | 2011-12-18 16:03:04 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2012-01-12 11:29:23 -0800 |
| commit | ddcf85d72ffe4fd46239a94253fe04c114d4d1e2 (patch) | |
| tree | e4da65c4289f3d529ac4c6e1f752e6dbbd1ebfd8 /arch/powerpc | |
| parent | 8e04782a06882913304916bc60960e4fc7405e18 (diff) | |
| download | lwn-ddcf85d72ffe4fd46239a94253fe04c114d4d1e2.tar.gz lwn-ddcf85d72ffe4fd46239a94253fe04c114d4d1e2.zip | |
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>
Diffstat (limited to 'arch/powerpc')
| -rw-r--r-- | arch/powerpc/platforms/pseries/hvCall_inst.c | 4 | ||||
| -rw-r--r-- | arch/powerpc/platforms/pseries/lpar.c | 2 |
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 f106662f4381..c9311cfdfcac 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 27a49508b410..dc36ea6c7727 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: |