ftrace_event_id_fops and event_id_read() is overcomplicated. 1. Change event_create_dir() to pass "data = call->event.type" to debugfs_create_file().
This means that ftrace_event_id_fops doesn't need .open() and event_id_read() can simply print (int)i_private 2. event_id_read() has no reason to kmalloc "struct trace_seq" (more than PAGE_SIZE!), it can use a small buffer. Note: "if (*ppos) return 0" looks strange and unneeded, simple_read_from_buffer(ppos) should handle this case corrrectly. Signed-off-by: Oleg Nesterov <[email protected]> --- kernel/trace/trace_events.c | 26 +++++++++----------------- 1 files changed, 9 insertions(+), 17 deletions(-) diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index cbd1a57..cefbe85 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -962,24 +962,17 @@ static int trace_format_open(struct inode *inode, struct file *file) static ssize_t event_id_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos) { - struct ftrace_event_call *call = filp->private_data; - struct trace_seq *s; - int r; + int id = (long)ACCESS_ONCE(file_inode(filp)->i_private); + char buf[32]; + int len; + if (!id) + return -ENODEV; if (*ppos) return 0; - s = kmalloc(sizeof(*s), GFP_KERNEL); - if (!s) - return -ENOMEM; - - trace_seq_init(s); - trace_seq_printf(s, "%d\n", call->event.type); - - r = simple_read_from_buffer(ubuf, cnt, ppos, - s->buffer, s->len); - kfree(s); - return r; + len = sprintf(buf, "%d\n", id); + return simple_read_from_buffer(ubuf, cnt, ppos, buf, len); } static ssize_t @@ -1264,7 +1257,6 @@ static const struct file_operations ftrace_event_format_fops = { }; static const struct file_operations ftrace_event_id_fops = { - .open = tracing_open_generic, .read = event_id_read, .llseek = default_llseek, }; @@ -1496,8 +1488,8 @@ event_create_dir(struct dentry *parent, #ifdef CONFIG_PERF_EVENTS if (call->event.type && call->class->reg) - trace_create_file("id", 0444, file->dir, call, - id); + trace_create_file("id", 0444, file->dir, + (void*)(long)call->event.type, id); #endif /* -- 1.5.5.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
