diff options
Diffstat (limited to 'kernel/trace')
| -rw-r--r-- | kernel/trace/trace.c | 145 |
1 files changed, 137 insertions, 8 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 3b4eaf36ed5..4723e012151 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -35,6 +35,15 @@ unsigned long __read_mostly tracing_max_latency = (cycle_t)ULONG_MAX; unsigned long __read_mostly tracing_thresh; +/* dummy trace to disable tracing */ +static struct tracer no_tracer __read_mostly = +{ + .name = "none", +}; + +static int trace_alloc_page(void); +static int trace_free_page(void); + static int tracing_disabled = 1; long @@ -2364,6 +2373,70 @@ tracing_read_pipe(struct file *filp, char __user *ubuf, return read; } +static ssize_t +tracing_entries_read(struct file *filp, char __user *ubuf, + size_t cnt, loff_t *ppos) +{ + struct trace_array *tr = filp->private_data; + char buf[64]; + int r; + + r = sprintf(buf, "%lu\n", tr->entries); + return simple_read_from_buffer(ubuf, cnt, ppos, buf, r); +} + +static ssize_t +tracing_entries_write(struct file *filp, const char __user *ubuf, + size_t cnt, loff_t *ppos) +{ + unsigned long val; + char buf[64]; + + if (cnt > 63) + cnt = 63; + + if (copy_from_user(&buf, ubuf, cnt)) + return -EFAULT; + + buf[cnt] = 0; + + val = simple_strtoul(buf, NULL, 10); + + /* must have at least 1 entry */ + if (!val) + return -EINVAL; + + mutex_lock(&trace_types_lock); + + if (current_trace != &no_tracer) { + cnt = -EBUSY; + pr_info("ftrace: set current_tracer to none" + " before modifying buffer size\n"); + goto out; + } + + if (val > global_trace.entries) { + while (global_trace.entries < val) { + if (trace_alloc_page()) { + cnt = -ENOMEM; + goto out; + } + } + } else { + /* include the number of entries in val (inc of page entries) */ + while (global_trace.entries > val + (ENTRIES_PER_PAGE - 1)) + trace_free_page(); + } + + filp->f_pos += cnt; + + out: + max_tr.entries = global_trace.entries; + mutex_unlock(&trace_types_lock); + + return cnt; +} + static struct file_operations tracing_max_lat_fops = { .open = tracing_open_generic, .read = tracing_max_lat_read, @@ -2389,6 +2462,12 @@ static struct file_operations tracing_pipe_fops = { .release = tracing_release_pipe, }; +static struct file_operations tracing_entries_fops = { + .open = tracing_open_generic, + .read = tracing_entries_read, + .write = tracing_entries_write, +}; + #ifdef CONFIG_DYNAMIC_FTRACE static ssize_t @@ -2500,6 +2579,12 @@ static __init void tracer_init_debugfs(void) pr_warning("Could not create debugfs " "'tracing_threash' entry\n"); + entry = debugfs_create_file("trace_entries", 0644, d_tracer, + &global_trace, &tracing_entries_fops); + if (!entry) + pr_warning("Could not create debugfs " + "'tracing_threash' entry\n"); + #ifdef CONFIG_DYNAMIC_FTRACE entry = debugfs_create_file("dyn_ftrace_total_info", 0444, d_tracer, &ftrace_update_tot_cnt, @@ -2510,12 +2595,6 @@ static __init void tracer_init_debugfs(void) #endif } -/* dummy trace to disable tracing */ -static struct tracer no_tracer __read_mostly = -{ - .name = "none", -}; - static int trace_alloc_page(void) { struct trace_array_cpu *data; @@ -2552,7 +2631,6 @@ static int trace_alloc_page(void) /* Now that we successfully allocate a page per CPU, add them */ for_each_possible_cpu(i) { data = global_trace.data[i]; - data->lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED; page = list_entry(pages.next, struct page, lru); list_del_init(&page->lru); list_add_tail(&page->lru, &data->trace_pages); @@ -2560,7 +2638,6 @@ static int trace_alloc_page(void) #ifdef CONFIG_TRACER_MAX_TRACE data = max_tr.data[i]; - data->lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED; page = list_entry(pages.next, struct page, lru); list_del_init(&page->lru); list_add_tail(&page->lru, &data->trace_pages); @@ -2579,6 +2656,55 @@ static int trace_alloc_page(void) return -ENOMEM; } +static int trace_free_page(void) +{ + struct trace_array_cpu *data; + struct page *page; + struct list_head *p; + int i; + int ret = 0; + + /* free one page from each buffer */ + for_each_possible_cpu(i) { + data = global_trace.data[i]; + p = data->trace_pages.next; + if (p == &data->trace_pages) { + /* should never happen */ + WARN_ON(1); + tracing_disabled = 1; + ret = -1; + break; + } + page = list_entry(p, struct page, lru); + ClearPageLRU(page); + list_del(&page->lru); + __free_page(page); + + tracing_reset(data); + +#ifdef CONFIG_TRACER_MAX_TRACE + data = max_tr.data[i]; + p = data->trace_pages.next; + if (p == &data->trace_pages) { + /* should never happen */ + WARN_ON(1); + tracing_disabled = 1; + ret = -1; + break; + } + page = list_entry(p, struct page, lru); + ClearPageLRU(page); + list_del(&page->lru); + __free_page(page); + + tracing_reset(data); +#endif + } + global_trace.entries -= ENTRIES_PER_PAGE; + + return ret; +} + __init static int tracer_alloc_buffers(void) { struct trace_array_cpu *data; @@ -2609,6 +2735,9 @@ __init static int tracer_alloc_buffers(void) /* use the LRU flag to differentiate the two buffers */ ClearPageLRU(page); + data->lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED; + max_tr.data[i]->lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED; + /* Only allocate if we are actually using the max trace */ #ifdef CONFIG_TRACER_MAX_TRACE array = (void *)__get_free_page(GFP_KERNEL); |