• Tim Pepper's avatar
    lockdep: Avoid /proc/lockdep & lock_stat infinite output · 94c61c0a
    Tim Pepper authored
    Both /proc/lockdep and /proc/lock_stat output may loop infinitely.
    
    When a read() requests an amount of data smaller than the amount of data
    that the seq_file's foo_show() outputs, the output starts looping and
    outputs the "stuck" element's data infinitely.  There may be multiple
    sequential calls to foo_start(), foo_next()/foo_show(), and foo_stop()
    for a single open with sequential read of the file.  The _start() does not
    have to start with the 0th element and _show() might be called multiple
    times in a row for the same element for a given open/read of the seq_file.
    
    Also header output should not be happening in _start().  All output should
    be in _show(), which SEQ_START_TOKEN is meant to help.  Having output in
    _start() may also negatively impact seq_file's seq_read() and traverse()
    accounting.
    Signed-off-by: default avatarTim Pepper <lnxninja@linux.vnet.ibm.com>
    Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
    Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
    Cc: Ingo Molnar <mingo@elte.hu>
    Cc: Al Viro <viro@ftp.linux.org.uk>
    94c61c0a
lockdep_proc.c 17 KB