[PATCH v8 1/4] nmi_backtrace: add more trigger_*_cpu_backtrace() methods
From: pmladek@suse.com (Petr Mladek)
Date: 2016-08-18 14:38:25
Also in:
linux-mips, lkml, sparclinux
On Tue 2016-08-16 15:50:21, Chris Metcalf wrote:
quoted hunk ↗ jump to hunk
Currently you can only request a backtrace of either all cpus, or all cpus but yourself. It can also be helpful to request a remote backtrace of a single cpu, and since we want that, the logical extension is to support a cpumask as the underlying primitive. This change modifies the existing lib/nmi_backtrace.c code to take a cpumask as its basic primitive, and modifies the linux/nmi.h code to use the new "cpumask" method instead. The mips code ignored the "include_self" boolean but with this change it will now also dump a local backtrace if requested.diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c index 7429ad09fbe3..fea1fa7726e3 100644 --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c@@ -569,9 +569,16 @@ static void arch_dump_stack(void *info) dump_stack(); } -void arch_trigger_all_cpu_backtrace(bool include_self) +void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self) { - smp_call_function(arch_dump_stack, NULL, 1); + long this_cpu = get_cpu(); + + if (cpumask_test_cpu(this_cpu, mask) && !exclude_self) + dump_stack();
The bit is not cleared in the mask. Therefore arch_dump_stack will get called for this CPU as well. We could either use similar tricks as in lib/nmi_backtrace(). I mean to copy the mask into a global variable and prevent parallel call with a backtrace_flag. Or we could ignore the exclude_self flag as it was done before. It is a separate problem after all and it need not be solved in this patch(set).
+ + smp_call_function_many(mask, arch_dump_stack, NULL, 1); + + put_cpu(); }
Otherwise the patch patch looks good to me. Best Regards, Petr