X-Git-Url: http://git.cascardo.eti.br/?a=blobdiff_plain;f=lib%2Fnmi_backtrace.c;h=75554754eadfeac67e7ab160ad8e6aa45b2392ce;hb=c6fcc4fc5f8b592600c7409e769ab68da0fb1eca;hp=26caf51cc2383e80bc1902c6c65b66102e8d5af0;hpb=e82a82c19f4272ea5437cc76e5711b98e2ee6223;p=cascardo%2Flinux.git

diff --git a/lib/nmi_backtrace.c b/lib/nmi_backtrace.c
index 26caf51cc238..75554754eadf 100644
--- a/lib/nmi_backtrace.c
+++ b/lib/nmi_backtrace.c
@@ -16,21 +16,23 @@
 #include <linux/delay.h>
 #include <linux/kprobes.h>
 #include <linux/nmi.h>
+#include <linux/cpu.h>
 
-#ifdef arch_trigger_all_cpu_backtrace
+#ifdef arch_trigger_cpumask_backtrace
 /* For reliability, we're prepared to waste bits here. */
 static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly;
 
-/* "in progress" flag of arch_trigger_all_cpu_backtrace */
+/* "in progress" flag of arch_trigger_cpumask_backtrace */
 static unsigned long backtrace_flag;
 
 /*
- * When raise() is called it will be is passed a pointer to the
+ * When raise() is called it will be passed a pointer to the
  * backtrace_mask. Architectures that call nmi_cpu_backtrace()
  * directly from their raise() functions may rely on the mask
  * they are passed being updated as a side effect of this call.
  */
-void nmi_trigger_all_cpu_backtrace(bool include_self,
+void nmi_trigger_cpumask_backtrace(const cpumask_t *mask,
+				   bool exclude_self,
 				   void (*raise)(cpumask_t *mask))
 {
 	int i, this_cpu = get_cpu();
@@ -44,13 +46,22 @@ void nmi_trigger_all_cpu_backtrace(bool include_self,
 		return;
 	}
 
-	cpumask_copy(to_cpumask(backtrace_mask), cpu_online_mask);
-	if (!include_self)
+	cpumask_copy(to_cpumask(backtrace_mask), mask);
+	if (exclude_self)
 		cpumask_clear_cpu(this_cpu, to_cpumask(backtrace_mask));
 
+	/*
+	 * Don't try to send an NMI to this cpu; it may work on some
+	 * architectures, but on others it may not, and we'll get
+	 * information at least as useful just by doing a dump_stack() here.
+	 * Note that nmi_cpu_backtrace(NULL) will clear the cpu bit.
+	 */
+	if (cpumask_test_cpu(this_cpu, to_cpumask(backtrace_mask)))
+		nmi_cpu_backtrace(NULL);
+
 	if (!cpumask_empty(to_cpumask(backtrace_mask))) {
-		pr_info("Sending NMI to %s CPUs:\n",
-			(include_self ? "all" : "other"));
+		pr_info("Sending NMI from CPU %d to CPUs %*pbl:\n",
+			this_cpu, nr_cpumask_bits, to_cpumask(backtrace_mask));
 		raise(to_cpumask(backtrace_mask));
 	}
 
@@ -77,11 +88,16 @@ bool nmi_cpu_backtrace(struct pt_regs *regs)
 	int cpu = smp_processor_id();
 
 	if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
-		pr_warn("NMI backtrace for cpu %d\n", cpu);
-		if (regs)
-			show_regs(regs);
-		else
-			dump_stack();
+		if (regs && cpu_in_idle(instruction_pointer(regs))) {
+			pr_warn("NMI backtrace for cpu %d skipped: idling at pc %#lx\n",
+				cpu, instruction_pointer(regs));
+		} else {
+			pr_warn("NMI backtrace for cpu %d\n", cpu);
+			if (regs)
+				show_regs(regs);
+			else
+				dump_stack();
+		}
 		cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
 		return true;
 	}