f6c9b16023
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>
33 lines
671 B
C
33 lines
671 B
C
/*
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* Tracepoint definitions for s390
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*
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* Copyright IBM Corp. 2015
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* Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
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*/
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#include <linux/percpu.h>
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#define CREATE_TRACE_POINTS
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#include <asm/trace/diag.h>
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EXPORT_TRACEPOINT_SYMBOL(s390_diagnose);
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static DEFINE_PER_CPU(unsigned int, diagnose_trace_depth);
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void trace_s390_diagnose_norecursion(int diag_nr)
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{
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unsigned long flags;
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unsigned int *depth;
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/* Avoid lockdep recursion. */
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if (IS_ENABLED(CONFIG_LOCKDEP))
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return;
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local_irq_save(flags);
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depth = this_cpu_ptr(&diagnose_trace_depth);
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if (*depth == 0) {
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(*depth)++;
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trace_s390_diagnose(diag_nr);
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(*depth)--;
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}
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local_irq_restore(flags);
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}
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