4b3e3d2284
Impact: prevent deadlock if ring buffer gets corrupted This patch adds a paranoid check to make sure the ring buffer consumer does not go into an infinite loop. Since the ring buffer has been set to read only, the consumer should not loop for more than the ring buffer size. A check is added to make sure the consumer does not loop more than the ring buffer size. Signed-off-by: Steven Rostedt <srostedt@redhat.com>
636 lines
13 KiB
C
636 lines
13 KiB
C
/* Include in trace.c */
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#include <linux/kthread.h>
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#include <linux/delay.h>
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static inline int trace_valid_entry(struct trace_entry *entry)
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{
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switch (entry->type) {
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case TRACE_FN:
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case TRACE_CTX:
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case TRACE_WAKE:
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case TRACE_CONT:
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case TRACE_STACK:
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case TRACE_PRINT:
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case TRACE_SPECIAL:
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case TRACE_BRANCH:
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return 1;
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}
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return 0;
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}
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static int trace_test_buffer_cpu(struct trace_array *tr, int cpu)
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{
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struct ring_buffer_event *event;
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struct trace_entry *entry;
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unsigned int loops = 0;
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while ((event = ring_buffer_consume(tr->buffer, cpu, NULL))) {
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entry = ring_buffer_event_data(event);
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/*
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* The ring buffer is a size of trace_buf_size, if
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* we loop more than the size, there's something wrong
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* with the ring buffer.
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*/
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if (loops++ > trace_buf_size) {
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printk(KERN_CONT ".. bad ring buffer ");
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goto failed;
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}
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if (!trace_valid_entry(entry)) {
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printk(KERN_CONT ".. invalid entry %d ",
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entry->type);
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goto failed;
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}
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}
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return 0;
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failed:
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/* disable tracing */
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tracing_disabled = 1;
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printk(KERN_CONT ".. corrupted trace buffer .. ");
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return -1;
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}
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/*
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* Test the trace buffer to see if all the elements
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* are still sane.
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*/
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static int trace_test_buffer(struct trace_array *tr, unsigned long *count)
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{
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unsigned long flags, cnt = 0;
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int cpu, ret = 0;
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/* Don't allow flipping of max traces now */
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local_irq_save(flags);
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__raw_spin_lock(&ftrace_max_lock);
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cnt = ring_buffer_entries(tr->buffer);
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/*
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* The trace_test_buffer_cpu runs a while loop to consume all data.
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* If the calling tracer is broken, and is constantly filling
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* the buffer, this will run forever, and hard lock the box.
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* We disable the ring buffer while we do this test to prevent
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* a hard lock up.
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*/
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tracing_off();
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for_each_possible_cpu(cpu) {
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ret = trace_test_buffer_cpu(tr, cpu);
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if (ret)
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break;
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}
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tracing_on();
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__raw_spin_unlock(&ftrace_max_lock);
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local_irq_restore(flags);
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if (count)
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*count = cnt;
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return ret;
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}
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static inline void warn_failed_init_tracer(struct tracer *trace, int init_ret)
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{
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printk(KERN_WARNING "Failed to init %s tracer, init returned %d\n",
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trace->name, init_ret);
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}
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#ifdef CONFIG_FUNCTION_TRACER
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#ifdef CONFIG_DYNAMIC_FTRACE
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#define __STR(x) #x
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#define STR(x) __STR(x)
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/* Test dynamic code modification and ftrace filters */
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int trace_selftest_startup_dynamic_tracing(struct tracer *trace,
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struct trace_array *tr,
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int (*func)(void))
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{
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int save_ftrace_enabled = ftrace_enabled;
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int save_tracer_enabled = tracer_enabled;
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unsigned long count;
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char *func_name;
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int ret;
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/* The ftrace test PASSED */
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printk(KERN_CONT "PASSED\n");
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pr_info("Testing dynamic ftrace: ");
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/* enable tracing, and record the filter function */
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ftrace_enabled = 1;
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tracer_enabled = 1;
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/* passed in by parameter to fool gcc from optimizing */
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func();
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/*
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* Some archs *cough*PowerPC*cough* add charachters to the
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* start of the function names. We simply put a '*' to
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* accomodate them.
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*/
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func_name = "*" STR(DYN_FTRACE_TEST_NAME);
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/* filter only on our function */
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ftrace_set_filter(func_name, strlen(func_name), 1);
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/* enable tracing */
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ret = trace->init(tr);
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if (ret) {
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warn_failed_init_tracer(trace, ret);
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goto out;
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}
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/* Sleep for a 1/10 of a second */
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msleep(100);
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/* we should have nothing in the buffer */
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ret = trace_test_buffer(tr, &count);
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if (ret)
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goto out;
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if (count) {
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ret = -1;
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printk(KERN_CONT ".. filter did not filter .. ");
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goto out;
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}
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/* call our function again */
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func();
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/* sleep again */
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msleep(100);
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/* stop the tracing. */
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tracing_stop();
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ftrace_enabled = 0;
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/* check the trace buffer */
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ret = trace_test_buffer(tr, &count);
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trace->reset(tr);
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tracing_start();
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/* we should only have one item */
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if (!ret && count != 1) {
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printk(KERN_CONT ".. filter failed count=%ld ..", count);
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ret = -1;
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goto out;
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}
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out:
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ftrace_enabled = save_ftrace_enabled;
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tracer_enabled = save_tracer_enabled;
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/* Enable tracing on all functions again */
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ftrace_set_filter(NULL, 0, 1);
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return ret;
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}
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#else
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# define trace_selftest_startup_dynamic_tracing(trace, tr, func) ({ 0; })
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#endif /* CONFIG_DYNAMIC_FTRACE */
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/*
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* Simple verification test of ftrace function tracer.
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* Enable ftrace, sleep 1/10 second, and then read the trace
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* buffer to see if all is in order.
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*/
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int
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trace_selftest_startup_function(struct tracer *trace, struct trace_array *tr)
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{
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int save_ftrace_enabled = ftrace_enabled;
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int save_tracer_enabled = tracer_enabled;
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unsigned long count;
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int ret;
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/* make sure msleep has been recorded */
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msleep(1);
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/* start the tracing */
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ftrace_enabled = 1;
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tracer_enabled = 1;
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ret = trace->init(tr);
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if (ret) {
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warn_failed_init_tracer(trace, ret);
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goto out;
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}
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/* Sleep for a 1/10 of a second */
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msleep(100);
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/* stop the tracing. */
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tracing_stop();
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ftrace_enabled = 0;
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/* check the trace buffer */
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ret = trace_test_buffer(tr, &count);
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trace->reset(tr);
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tracing_start();
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if (!ret && !count) {
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printk(KERN_CONT ".. no entries found ..");
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ret = -1;
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goto out;
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}
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ret = trace_selftest_startup_dynamic_tracing(trace, tr,
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DYN_FTRACE_TEST_NAME);
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out:
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ftrace_enabled = save_ftrace_enabled;
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tracer_enabled = save_tracer_enabled;
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/* kill ftrace totally if we failed */
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if (ret)
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ftrace_kill();
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return ret;
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}
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#endif /* CONFIG_FUNCTION_TRACER */
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#ifdef CONFIG_IRQSOFF_TRACER
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int
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trace_selftest_startup_irqsoff(struct tracer *trace, struct trace_array *tr)
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{
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unsigned long save_max = tracing_max_latency;
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unsigned long count;
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int ret;
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/* start the tracing */
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ret = trace->init(tr);
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if (ret) {
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warn_failed_init_tracer(trace, ret);
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return ret;
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}
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/* reset the max latency */
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tracing_max_latency = 0;
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/* disable interrupts for a bit */
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local_irq_disable();
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udelay(100);
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local_irq_enable();
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/* stop the tracing. */
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tracing_stop();
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/* check both trace buffers */
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ret = trace_test_buffer(tr, NULL);
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if (!ret)
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ret = trace_test_buffer(&max_tr, &count);
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trace->reset(tr);
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tracing_start();
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if (!ret && !count) {
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printk(KERN_CONT ".. no entries found ..");
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ret = -1;
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}
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tracing_max_latency = save_max;
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return ret;
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}
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#endif /* CONFIG_IRQSOFF_TRACER */
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#ifdef CONFIG_PREEMPT_TRACER
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int
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trace_selftest_startup_preemptoff(struct tracer *trace, struct trace_array *tr)
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{
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unsigned long save_max = tracing_max_latency;
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unsigned long count;
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int ret;
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/*
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* Now that the big kernel lock is no longer preemptable,
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* and this is called with the BKL held, it will always
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* fail. If preemption is already disabled, simply
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* pass the test. When the BKL is removed, or becomes
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* preemptible again, we will once again test this,
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* so keep it in.
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*/
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if (preempt_count()) {
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printk(KERN_CONT "can not test ... force ");
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return 0;
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}
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/* start the tracing */
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ret = trace->init(tr);
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if (ret) {
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warn_failed_init_tracer(trace, ret);
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return ret;
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}
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/* reset the max latency */
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tracing_max_latency = 0;
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/* disable preemption for a bit */
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preempt_disable();
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udelay(100);
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preempt_enable();
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/* stop the tracing. */
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tracing_stop();
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/* check both trace buffers */
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ret = trace_test_buffer(tr, NULL);
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if (!ret)
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ret = trace_test_buffer(&max_tr, &count);
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trace->reset(tr);
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tracing_start();
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if (!ret && !count) {
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printk(KERN_CONT ".. no entries found ..");
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ret = -1;
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}
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tracing_max_latency = save_max;
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return ret;
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}
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#endif /* CONFIG_PREEMPT_TRACER */
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#if defined(CONFIG_IRQSOFF_TRACER) && defined(CONFIG_PREEMPT_TRACER)
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int
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trace_selftest_startup_preemptirqsoff(struct tracer *trace, struct trace_array *tr)
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{
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unsigned long save_max = tracing_max_latency;
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unsigned long count;
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int ret;
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/*
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* Now that the big kernel lock is no longer preemptable,
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* and this is called with the BKL held, it will always
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* fail. If preemption is already disabled, simply
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* pass the test. When the BKL is removed, or becomes
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* preemptible again, we will once again test this,
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* so keep it in.
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*/
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if (preempt_count()) {
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printk(KERN_CONT "can not test ... force ");
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return 0;
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}
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/* start the tracing */
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ret = trace->init(tr);
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if (ret) {
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warn_failed_init_tracer(trace, ret);
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goto out;
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}
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/* reset the max latency */
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tracing_max_latency = 0;
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/* disable preemption and interrupts for a bit */
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preempt_disable();
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local_irq_disable();
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udelay(100);
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preempt_enable();
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/* reverse the order of preempt vs irqs */
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local_irq_enable();
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/* stop the tracing. */
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tracing_stop();
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/* check both trace buffers */
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ret = trace_test_buffer(tr, NULL);
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if (ret) {
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tracing_start();
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goto out;
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}
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ret = trace_test_buffer(&max_tr, &count);
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if (ret) {
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tracing_start();
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goto out;
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}
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if (!ret && !count) {
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printk(KERN_CONT ".. no entries found ..");
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ret = -1;
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tracing_start();
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goto out;
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}
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/* do the test by disabling interrupts first this time */
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tracing_max_latency = 0;
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tracing_start();
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preempt_disable();
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local_irq_disable();
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udelay(100);
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preempt_enable();
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/* reverse the order of preempt vs irqs */
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local_irq_enable();
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/* stop the tracing. */
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tracing_stop();
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/* check both trace buffers */
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ret = trace_test_buffer(tr, NULL);
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if (ret)
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goto out;
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ret = trace_test_buffer(&max_tr, &count);
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if (!ret && !count) {
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printk(KERN_CONT ".. no entries found ..");
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ret = -1;
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goto out;
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}
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out:
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trace->reset(tr);
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tracing_start();
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tracing_max_latency = save_max;
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return ret;
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}
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#endif /* CONFIG_IRQSOFF_TRACER && CONFIG_PREEMPT_TRACER */
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#ifdef CONFIG_NOP_TRACER
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int
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trace_selftest_startup_nop(struct tracer *trace, struct trace_array *tr)
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{
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/* What could possibly go wrong? */
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return 0;
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}
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#endif
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#ifdef CONFIG_SCHED_TRACER
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static int trace_wakeup_test_thread(void *data)
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{
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/* Make this a RT thread, doesn't need to be too high */
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struct sched_param param = { .sched_priority = 5 };
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struct completion *x = data;
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sched_setscheduler(current, SCHED_FIFO, ¶m);
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/* Make it know we have a new prio */
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complete(x);
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/* now go to sleep and let the test wake us up */
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set_current_state(TASK_INTERRUPTIBLE);
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schedule();
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/* we are awake, now wait to disappear */
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while (!kthread_should_stop()) {
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/*
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* This is an RT task, do short sleeps to let
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* others run.
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*/
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msleep(100);
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}
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return 0;
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}
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int
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trace_selftest_startup_wakeup(struct tracer *trace, struct trace_array *tr)
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{
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unsigned long save_max = tracing_max_latency;
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struct task_struct *p;
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struct completion isrt;
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unsigned long count;
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int ret;
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init_completion(&isrt);
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/* create a high prio thread */
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p = kthread_run(trace_wakeup_test_thread, &isrt, "ftrace-test");
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if (IS_ERR(p)) {
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printk(KERN_CONT "Failed to create ftrace wakeup test thread ");
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return -1;
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}
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/* make sure the thread is running at an RT prio */
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wait_for_completion(&isrt);
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/* start the tracing */
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ret = trace->init(tr);
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if (ret) {
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warn_failed_init_tracer(trace, ret);
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return ret;
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}
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/* reset the max latency */
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tracing_max_latency = 0;
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/* sleep to let the RT thread sleep too */
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msleep(100);
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/*
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* Yes this is slightly racy. It is possible that for some
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* strange reason that the RT thread we created, did not
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* call schedule for 100ms after doing the completion,
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* and we do a wakeup on a task that already is awake.
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* But that is extremely unlikely, and the worst thing that
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* happens in such a case, is that we disable tracing.
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* Honestly, if this race does happen something is horrible
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* wrong with the system.
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*/
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wake_up_process(p);
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/* give a little time to let the thread wake up */
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msleep(100);
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/* stop the tracing. */
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tracing_stop();
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/* check both trace buffers */
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ret = trace_test_buffer(tr, NULL);
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if (!ret)
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ret = trace_test_buffer(&max_tr, &count);
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trace->reset(tr);
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tracing_start();
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tracing_max_latency = save_max;
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/* kill the thread */
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kthread_stop(p);
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if (!ret && !count) {
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printk(KERN_CONT ".. no entries found ..");
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ret = -1;
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}
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return ret;
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}
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#endif /* CONFIG_SCHED_TRACER */
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#ifdef CONFIG_CONTEXT_SWITCH_TRACER
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int
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trace_selftest_startup_sched_switch(struct tracer *trace, struct trace_array *tr)
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{
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unsigned long count;
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int ret;
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/* start the tracing */
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ret = trace->init(tr);
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if (ret) {
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warn_failed_init_tracer(trace, ret);
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return ret;
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}
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/* Sleep for a 1/10 of a second */
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msleep(100);
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/* stop the tracing. */
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tracing_stop();
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/* check the trace buffer */
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ret = trace_test_buffer(tr, &count);
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trace->reset(tr);
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tracing_start();
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if (!ret && !count) {
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printk(KERN_CONT ".. no entries found ..");
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ret = -1;
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}
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return ret;
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}
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#endif /* CONFIG_CONTEXT_SWITCH_TRACER */
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#ifdef CONFIG_SYSPROF_TRACER
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int
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trace_selftest_startup_sysprof(struct tracer *trace, struct trace_array *tr)
|
|
{
|
|
unsigned long count;
|
|
int ret;
|
|
|
|
/* start the tracing */
|
|
ret = trace->init(tr);
|
|
if (ret) {
|
|
warn_failed_init_tracer(trace, ret);
|
|
return 0;
|
|
}
|
|
|
|
/* Sleep for a 1/10 of a second */
|
|
msleep(100);
|
|
/* stop the tracing. */
|
|
tracing_stop();
|
|
/* check the trace buffer */
|
|
ret = trace_test_buffer(tr, &count);
|
|
trace->reset(tr);
|
|
tracing_start();
|
|
|
|
return ret;
|
|
}
|
|
#endif /* CONFIG_SYSPROF_TRACER */
|
|
|
|
#ifdef CONFIG_BRANCH_TRACER
|
|
int
|
|
trace_selftest_startup_branch(struct tracer *trace, struct trace_array *tr)
|
|
{
|
|
unsigned long count;
|
|
int ret;
|
|
|
|
/* start the tracing */
|
|
ret = trace->init(tr);
|
|
if (ret) {
|
|
warn_failed_init_tracer(trace, ret);
|
|
return ret;
|
|
}
|
|
|
|
/* Sleep for a 1/10 of a second */
|
|
msleep(100);
|
|
/* stop the tracing. */
|
|
tracing_stop();
|
|
/* check the trace buffer */
|
|
ret = trace_test_buffer(tr, &count);
|
|
trace->reset(tr);
|
|
tracing_start();
|
|
|
|
return ret;
|
|
}
|
|
#endif /* CONFIG_BRANCH_TRACER */
|