• Tejun Heo's avatar
    sysfs: use seq_file when reading regular files · 13c589d5
    Tejun Heo authored
    
    
    sysfs read path implements its own buffering scheme between userland
    and kernel callbacks, which essentially is a degenerate duplicate of
    seq_file.  This patch replaces the custom read buffering
    implementation in sysfs with seq_file.
    
    While the amount of code reduction is small, this reduces low level
    hairiness and enables future development of a new versatile API based
    on seq_file so that sysfs features can be shared with other
    subsystems.
    
    As write path was already converted to not use sysfs_open_file->page,
    this patch makes ->page and ->count unused and removes them.
    
    Userland behavior remains the same except for some extreme corner
    cases - e.g. sysfs will now regenerate the content each time a file is
    read after a non-contiguous seek whereas the original code would keep
    using the same content.  While this is a userland visible behavior
    change, it is extremely unlikely to be noticeable and brings sysfs
    behavior closer to that of procfs.
    Signed-off-by: default avatarTejun Heo <tj@kernel.org>
    Cc: Kay Sievers <kay@vrfy.org>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    13c589d5