• Steven Rostedt's avatar
    tracing: make trace_seq operations available for core kernel · 9504504c
    Steven Rostedt authored
    In the process to make TRACE_EVENT macro work for modules, the trace_seq
    operations must be available for core kernel code.
    
    These operations are quite useful and can be used for other implementations.
    
    The main idea is that we create a trace_seq handle that acts very much
    like the seq_file handle.
    
    	struct trace_seq *s = kmalloc(sizeof(*s, GFP_KERNEL);
    
    	trace_seq_init(s);
    	trace_seq_printf(s, "some data %d\n", variable);
    
    	printk("%s", s->buffer);
    
    The main use is to allow a top level function call several other functions
    that may store printf like data into the buffer. Then at the end, the top
    level function can process all the data with any method it would like to.
    It could be passed to userspace, output via printk or even use seq_file:
    
    	trace_seq_to_user(s, ubuf, cnt);
    	seq_puts(m, s->buffer);
    Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    9504504c
trace_output.h 1.65 KB