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| author | Heiko Carstens <heiko.carstens@de.ibm.com> | 2016-02-10 13:13:24 (GMT) |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2016-02-11 12:05:56 (GMT) |
| commit | f6c9b160233f9b5afe926b91b55589b706076640 (patch) | |
| tree | 7fe708f6f676a02294012a59ef4e7c4f0dab5afc /arch/s390 | |
| parent | 9d862ababb609439c5d6987f6d3ddd09e703aa0b (diff) | |
| download | linux-f6c9b160233f9b5afe926b91b55589b706076640.tar.xz | |
s390/diag: avoid lockdep recursion
The diagnose tracer will indirectly call back into the lockdep code
when lockdep does not expect it (arch_spinlock). This causes lockdep
to disable itself and therefore we don't have a working lock
dependency validator anymore.
This patch effectively disables tracing of diag 0x9c and 0x44 if
lockdep is enabled. If however lockdep is enabled spinlocks are
mainly implemented using a trylock variant, which will not issue any
diag 0x9c or 0x44. So this change has hardly any effect on tracing
except when arch_spinlock and friends are explicitly used.
Reported-and-Tested-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390')
| -rw-r--r-- | arch/s390/kernel/trace.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/s390/kernel/trace.c b/arch/s390/kernel/trace.c index 21a5df9..dde7654 100644 --- a/arch/s390/kernel/trace.c +++ b/arch/s390/kernel/trace.c @@ -18,6 +18,9 @@ void trace_s390_diagnose_norecursion(int diag_nr) unsigned long flags; unsigned int *depth; + /* Avoid lockdep recursion. */ + if (IS_ENABLED(CONFIG_LOCKDEP)) + return; local_irq_save(flags); depth = this_cpu_ptr(&diagnose_trace_depth); if (*depth == 0) { |