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backtrace: replace timer with tasklet + completions 

On qemu, the backtrace would show up _after_ the "end of backtrace
testing" message.

This patch changes it to use completions instead, which will guarantee
that no such race exists.

Cc: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Vegard Nossum 2008-06-27 18:06:54 +02:00 committed by Ingo Molnar
parent ad118c54a3
commit 4e6a0535dd
1 changed files with 26 additions and 11 deletions
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37
kernel/backtracetest.c
View File

@ -10,18 +10,39 @@
* of the License. * of the License.
*/ */
#include <linux/completion.h>
#include <linux/delay.h> #include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/module.h> #include <linux/module.h>
#include <linux/sched.h> #include <linux/sched.h>
#include <linux/stacktrace.h> #include <linux/stacktrace.h>
static struct timer_list backtrace_timer; static void backtrace_test_normal(void)
{
printk("Testing a backtrace from process context.\n");
printk("The following trace is a kernel self test and not a bug!\n");
static void backtrace_test_timer(unsigned long data) dump_stack();
}
static DECLARE_COMPLETION(backtrace_work);
static void backtrace_test_irq_callback(unsigned long data)
{
dump_stack();
complete(&backtrace_work);
}
static DECLARE_TASKLET(backtrace_tasklet, &backtrace_test_irq_callback, 0);
static void backtrace_test_irq(void)
{ {
printk("Testing a backtrace from irq context.\n"); printk("Testing a backtrace from irq context.\n");
printk("The following trace is a kernel self test and not a bug!\n"); printk("The following trace is a kernel self test and not a bug!\n");
dump_stack();
init_completion(&backtrace_work);
tasklet_schedule(&backtrace_tasklet);
wait_for_completion(&backtrace_work);
} }
#ifdef CONFIG_STACKTRACE #ifdef CONFIG_STACKTRACE
@ -51,17 +72,11 @@ static void backtrace_test_saved(void)
static int backtrace_regression_test(void) static int backtrace_regression_test(void)
{ {
printk("====[ backtrace testing ]===========\n"); printk("====[ backtrace testing ]===========\n");
printk("Testing a backtrace from process context.\n");
printk("The following trace is a kernel self test and not a bug!\n");
dump_stack();
backtrace_test_normal();
backtrace_test_irq();
backtrace_test_saved(); backtrace_test_saved();
init_timer(&backtrace_timer);
backtrace_timer.function = backtrace_test_timer;
mod_timer(&backtrace_timer, jiffies + 10);
msleep(10);
printk("====[ end of backtrace testing ]====\n"); printk("====[ end of backtrace testing ]====\n");
return 0; return 0;
} }