diff options
| author | Daniel Axtens <dja@axtens.net> | 2015-05-12 13:23:59 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2015-05-12 19:44:01 +1000 |
| commit | ffb2d78eca08a1451137583d4e435aecfd6af809 (patch) | |
| tree | 223ad3754bf3073f65509dfc045cb70290c429a2 /arch/powerpc/kernel/mce.c | |
| parent | 7b868e81be38d5ad4f4aa4be819a5fa543cc5ee8 (diff) | |
powerpc/mce: fix off by one errors in mce event handling
Before 69111bac42f5 ("powerpc: Replace __get_cpu_var uses"), in
save_mce_event, index got the value of mce_nest_count, and
mce_nest_count was incremented *after* index was set.
However, that patch changed the behaviour so that mce_nest count was
incremented *before* setting index.
This causes an off-by-one error, as get_mce_event sets index as
mce_nest_count - 1 before reading mce_event. Thus get_mce_event reads
bogus data, causing warnings like
"Machine Check Exception, Unknown event version 0 !"
and breaking MCEs handling.
Restore the old behaviour and unbreak MCE handling by subtracting one
from the newly incremented value.
The same broken change occured in machine_check_queue_event (which set
a queue read by machine_check_process_queued_event). Fix that too,
unbreaking printing of MCE information.
Fixes: 69111bac42f5 ("powerpc: Replace __get_cpu_var uses")
CC: stable@vger.kernel.org
CC: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
CC: Christoph Lameter <cl@linux.com>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/kernel/mce.c')
| -rw-r--r-- | arch/powerpc/kernel/mce.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/powerpc/kernel/mce.c b/arch/powerpc/kernel/mce.c index 15c99b649b04..b2eb4686bd8f 100644 --- a/arch/powerpc/kernel/mce.c +++ b/arch/powerpc/kernel/mce.c @@ -73,7 +73,7 @@ void save_mce_event(struct pt_regs *regs, long handled, uint64_t nip, uint64_t addr) { uint64_t srr1; - int index = __this_cpu_inc_return(mce_nest_count); + int index = __this_cpu_inc_return(mce_nest_count) - 1; struct machine_check_event *mce = this_cpu_ptr(&mce_event[index]); /* @@ -184,7 +184,7 @@ void machine_check_queue_event(void) if (!get_mce_event(&evt, MCE_EVENT_RELEASE)) return; - index = __this_cpu_inc_return(mce_queue_count); + index = __this_cpu_inc_return(mce_queue_count) - 1; /* If queue is full, just return for now. */ if (index >= MAX_MC_EVT) { __this_cpu_dec(mce_queue_count); |