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authorHeiko Carstens <heiko.carstens@de.ibm.com>2016-02-10 14:13:24 +0100
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2016-02-11 13:05:56 +0100
commitf6c9b160233f9b5afe926b91b55589b706076640 (patch)
tree7fe708f6f676a02294012a59ef4e7c4f0dab5afc /arch
parent9d862ababb609439c5d6987f6d3ddd09e703aa0b (diff)
downloadlinux-f6c9b160233f9b5afe926b91b55589b706076640.tar.bz2
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')
-rw-r--r--arch/s390/kernel/trace.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/s390/kernel/trace.c b/arch/s390/kernel/trace.c
index 21a5df99552b..dde7654f5c68 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) {