lkml.org 
[lkml]   [2008]   [Apr]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: ftrace and debugfs weird interaction
    On Sat, Apr 26, 2008 at 02:54:03PM -0400, Mathieu Desnoyers wrote:
    > Hi,
    >
    > When trying to figure out what was going on with the sched tracer
    > "tracing_enabled" file (sched-devel.git tree), I fell on this strange
    > behavior :
    >
    > echo 1>tracing_enabled seems _not_ to send 1 to the tracing_ctrl_write
    > callback. However, sending garbage, e.g. echo s> tracing_enabled,
    > correctly sends the 's' character down the chain. echo 0>tracing_enabled
    > sometimes results in the callback not even being called.
    >
    > The debugfs file has been created with
    >
    > entry = debugfs_create_file("tracing_enabled", 0644, d_tracer,
    > &global_trace, &tracing_ctrl_fops);
    > if (!entry)
    > pr_warning("Could not create debugfs 'tracing_enabled' entry\n");
    >
    > I wonder what kind of weird debugfs interaction we might have here ?

    I don't know. Are you sure your _fops is not getting called at all?

    How about using a "default" operation for such a simple file, like
    debugfs_create_bool() as that is all you care about for this kind of
    value?

    That should save you some code at the very least :)

    thanks,

    greg k-h


    \
     
     \ /
      Last update: 2008-04-27 02:47    [W:2.695 / U:0.032 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site