[PATCH] NMI lockup and AltSysRq-P dumping calltraces on _all_ cpusvia NMI IPI

From: Kirill Korotaev
Date: Wed May 11 2005 - 10:59:27 EST

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against 2.6.12-rc4

This patch adds dumping of calltraces on _all_ CPUs
on AltSysRq-P and NMI LOCKUP. It does this via sending
NMI IPI interrupts to the cpus.

I saw the same patch in RedHat kernels, here goes our own version of the patch, not sure it will be accepted, but I think it can be used by some people at least for debugging lockups etc.

Signed-Off-By: Kirill Korotaev <dev@xxxxx>
Signed-Off-By: Pavel Emelianov <xemul@xxxxx>

Kirill --- ./arch/i386/kernel/nmi.c.ipicalltraces 2005-05-10 16:09:58.000000000 +0400
+++ ./arch/i386/kernel/nmi.c 2005-05-10 18:20:00.000000000 +0400
@@ -476,6 +476,21 @@ void touch_nmi_watchdog (void)

extern void die_nmi(struct pt_regs *, const char *msg);

+static spinlock_t show_regs_lock = SPIN_LOCK_UNLOCKED;
+
+void smp_show_regs(struct pt_regs *regs, void *info)
+{
+ if (regs == NULL)
+ return;
+
+ bust_spinlocks(1);
+ spin_lock(&show_regs_lock);
+ printk("----------- IPI show regs -----------");
+ show_regs(regs);
+ spin_unlock(&show_regs_lock);
+ bust_spinlocks(0);
+}
+
void nmi_watchdog_tick (struct pt_regs * regs)
{

--- ./arch/i386/kernel/smp.c.ipicalltraces 2005-05-10 16:09:58.000000000 +0400
+++ ./arch/i386/kernel/smp.c 2005-05-10 18:28:08.000000000 +0400
@@ -20,6 +20,7 @@
#include <linux/cache.h>
#include <linux/interrupt.h>

+#include <asm/nmi.h>
#include <asm/mtrr.h>
#include <asm/tlbflush.h>
#include <mach_apic.h>
@@ -548,6 +549,89 @@ int smp_call_function (void (*func) (voi
return 0;
}

+static spinlock_t nmi_call_lock = SPIN_LOCK_UNLOCKED;
+static struct nmi_call_data_struct {
+ smp_nmi_function func;
+ void *info;
+ atomic_t started;
+ atomic_t finished;
+ cpumask_t cpus_called;
+ int wait;
+} *nmi_call_data;
+
+static int smp_nmi_callback(struct pt_regs * regs, int cpu)
+{
+ smp_nmi_function func;
+ void *info;
+ int wait;
+
+ func = nmi_call_data->func;
+ info = nmi_call_data->info;
+ wait = nmi_call_data->wait;
+ ack_APIC_irq();
+ /* prevent from calling func() multiple times */
+ if (cpu_test_and_set(cpu, nmi_call_data->cpus_called))
+ return 0;
+ /*
+ * notify initiating CPU that I've grabbed the data and am
+ * about to execute the function
+ */
+ mb();
+ atomic_inc(&nmi_call_data->started);
+ /* at this point the nmi_call_data structure is out of scope */
+ irq_enter();
+ func(regs, info);
+ irq_exit();
+ if (wait)
+ atomic_inc(&nmi_call_data->finished);
+
+ return 0;
+}
+
+/*
+ * This function tries to call func(regs, info) on each cpu.
+ * Func must be fast and non-blocking.
+ * May be called with disabled interrupts and from any context.
+ */
+int smp_nmi_call_function(smp_nmi_function func, void *info, int wait)
+{
+ struct nmi_call_data_struct data;
+ int cpus;
+
+ cpus = num_online_cpus() - 1;
+ if (!cpus)
+ return 0;
+
+ data.func = func;
+ data.info = info;
+ data.wait = wait;
+ atomic_set(&data.started, 0);
+ atomic_set(&data.finished, 0);
+ cpus_clear(data.cpus_called);
+ /* prevent this cpu from calling func if NMI happens */
+ cpu_set(smp_processor_id(), data.cpus_called);
+
+ if (!spin_trylock(&nmi_call_lock))
+ return -1;
+
+ nmi_call_data = &data;
+ set_nmi_ipi_callback(smp_nmi_callback);
+ mb();
+
+ /* Send a message to all other CPUs and wait for them to respond */
+ send_IPI_allbutself(APIC_DM_NMI);
+ while (atomic_read(&data.started) != cpus)
+ barrier();
+
+ unset_nmi_ipi_callback();
+ if (wait)
+ while (atomic_read(&data.finished) != cpus)
+ barrier();
+ spin_unlock(&nmi_call_lock);
+
+ return 0;
+}
+
static void stop_this_cpu (void * dummy)
{
/*
--- ./arch/i386/kernel/traps.c.ipicalltraces 2005-05-10 16:09:58.000000000 +0400
+++ ./arch/i386/kernel/traps.c 2005-05-10 18:27:04.000000000 +0400
@@ -565,6 +565,8 @@ void die_nmi (struct pt_regs *regs, cons
printk(" on CPU%d, eip %08lx, registers:\n",
smp_processor_id(), regs->eip);
show_registers(regs);
+ smp_nmi_call_function(smp_show_regs, NULL, 1);
+ bust_spinlocks(1);
printk("console shuts up ...\n");
console_silent();
spin_unlock(&nmi_print_lock);
@@ -616,6 +618,7 @@ static int dummy_nmi_callback(struct pt_
}

static nmi_callback_t nmi_callback = dummy_nmi_callback;
+static nmi_callback_t nmi_ipi_callback = dummy_nmi_callback;

fastcall void do_nmi(struct pt_regs * regs, long error_code)
{
@@ -629,9 +632,20 @@ fastcall void do_nmi(struct pt_regs * re
if (!nmi_callback(regs, cpu))
default_do_nmi(regs);

+ nmi_ipi_callback(regs, cpu);
nmi_exit();
}

+void set_nmi_ipi_callback(nmi_callback_t callback)
+{
+ nmi_ipi_callback = callback;
+}
+
+void unset_nmi_ipi_callback(void)
+{
+ nmi_ipi_callback = dummy_nmi_callback;
+}
+
void set_nmi_callback(nmi_callback_t callback)
{
nmi_callback = callback;
--- ./drivers/char/sysrq.c.ipicalltraces 2005-05-10 16:10:05.000000000 +0400
+++ ./drivers/char/sysrq.c 2005-05-10 18:20:00.000000000 +0400
@@ -143,8 +143,13 @@ static struct sysrq_key_op sysrq_mountro
static void sysrq_handle_showregs(int key, struct pt_regs *pt_regs,
struct tty_struct *tty)
{
+ bust_spinlocks(1);
if (pt_regs)
show_regs(pt_regs);
+ bust_spinlocks(0);
+#ifdef __i386__
+ smp_nmi_call_function(smp_show_regs, NULL, 0);
+#endif
}
static struct sysrq_key_op sysrq_showregs_op = {
.handler = sysrq_handle_showregs,
--- ./include/asm-i386/nmi.h.ipicalltraces 2005-03-02 10:37:54.000000000 +0300
+++ ./include/asm-i386/nmi.h 2005-05-10 18:20:00.000000000 +0400
@@ -17,6 +17,7 @@ typedef int (*nmi_callback_t)(struct pt_
* set. Return 1 if the NMI was handled.
*/
void set_nmi_callback(nmi_callback_t callback);
+void set_nmi_ipi_callback(nmi_callback_t callback);

/**
* unset_nmi_callback
@@ -24,5 +25,6 @@ void set_nmi_callback(nmi_callback_t cal
* Remove the handler previously set.
*/
void unset_nmi_callback(void);
+void unset_nmi_ipi_callback(void);

#endif /* ASM_NMI_H */
--- ./include/linux/sched.h.ipicalltraces 2005-05-10 16:10:39.000000000 +0400
+++ ./include/linux/sched.h 2005-05-10 18:20:00.000000000 +0400
@@ -160,6 +160,7 @@ extern cpumask_t nohz_cpu_mask;

extern void show_state(void);
extern void show_regs(struct pt_regs *);
+extern void smp_show_regs(struct pt_regs *, void *);

/*
* TASK is a pointer to the task whose backtrace we want to see (or NULL for current
--- ./include/linux/smp.h.ipicalltraces 2005-05-10 16:10:39.000000000 +0400
+++ ./include/linux/smp.h 2005-05-10 18:20:00.000000000 +0400
@@ -56,6 +56,9 @@ extern void smp_cpus_done(unsigned int m
extern int smp_call_function (void (*func) (void *info), void *info,
int retry, int wait);

+typedef void (*smp_nmi_function)(struct pt_regs *regs, void *info);
+extern int smp_nmi_call_function(smp_nmi_function func, void *info, int wait);
+
/*
* Call a function on all processors
*/
@@ -98,6 +101,7 @@ void smp_prepare_boot_cpu(void);
#endif
#define hard_smp_processor_id() 0
#define smp_call_function(func,info,retry,wait) ({ 0; })
+#define smp_nmi_call_function(func, info, wait) ({ 0; })
#define on_each_cpu(func,info,retry,wait) ({ func(info); 0; })
static inline void smp_send_reschedule(int cpu) { }
#define num_booting_cpus() 1

Next message: Badari Pulavarty: "Re: [RFC/PATCH 2/5] mm/fs: add execute in place support"
Previous message: Kirill Korotaev: "[PATCH] Fix of dcache race leading to busy inodes on umount"
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