[PATCH 7/7] percpu: Add debug detection of uninitialized usage of per_cpu variable
From: <hidden>
Date: 2008-01-18 18:32:03
Also in:
lkml
Provide a means to trap usages of per_cpu variables before the per_cpu_areas are setup. Define CONFIG_DEBUG_PER_CPU to activate. Signed-off-by: Mike Travis <redacted> --- include/asm-generic/percpu.h | 11 ++++++++++- lib/Kconfig.debug | 12 ++++++++++++ 2 files changed, 22 insertions(+), 1 deletion(-)
--- a/include/asm-generic/percpu.h
+++ b/include/asm-generic/percpu.h@@ -47,12 +47,21 @@ extern unsigned long __per_cpu_offset[NR #endif /* - * A percpu variable may point to a discarded reghions. The following are + * A percpu variable may point to a discarded regions. The following are * established ways to produce a usable pointer from the percpu variable * offset. */ +#ifdef CONFIG_DEBUG_PER_CPU +#define per_cpu(var, cpu) (*({ \ + if(!per_cpu_offset(cpu)) { \ + printk("KERN_NOTICE per_cpu(%s,%d): not available!\n", #var, (int)cpu); \ + BUG(); \ + } \ + SHIFT_PERCPU_PTR(&per_cpu_var(var), per_cpu_offset(cpu));})) +#else #define per_cpu(var, cpu) \ (*SHIFT_PERCPU_PTR(&per_cpu_var(var), per_cpu_offset(cpu))) +#endif #define __get_cpu_var(var) \ (*SHIFT_PERCPU_PTR(&per_cpu_var(var), my_cpu_offset)) #define __raw_get_cpu_var(var) \ --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug
@@ -610,6 +610,18 @@ config PROVIDE_OHCI1394_DMA_INIT See Documentation/debugging-via-ohci1394.txt for more information. +config DEBUG_PER_CPU + bool "Debug per_cpu usage" + depends on DEBUG_KERNEL + depends on SMP + default n + help + Say Y here to add code that verifies the per_cpu area is + setup before accessing a per_cpu variable. It does add a + significant amount of code to kernel memory. + + If unsure, say N. + source "samples/Kconfig" source "lib/Kconfig.kgdb"
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