• Neil Brown's avatar
    sysfs: Allow sysfs_notify_dirent to be called from interrupt context. · 83db93f4
    Neil Brown authored
    sysfs_notify_dirent is a simple atomic operation that can be used to
    alert user-space that new data can be read from a sysfs attribute.
    
    Unfortunately it cannot currently be called from non-process context
    because of its use of spin_lock which is sometimes taken with
    interrupts enabled.
    
    So change all lockers of sysfs_open_dirent_lock to disable interrupts,
    thus making sysfs_notify_dirent safe to be called from non-process
    context (as drivers/md does in md_safemode_timeout).
    
    sysfs_get_open_dirent is (documented as being) only called from
    process context, so it uses spin_lock_irq.  Other places
    use spin_lock_irqsave.
    
    The usage for sysfs_notify_dirent in md_safemode_timeout was
    introduced in 2.6.28, so this patch is suitable for that and more
    recent kernels.
    Reported-by: default avatarJoel Andres Granados <jgranado@redhat.com>
    Signed-off-by: default avatarNeilBrown <neilb@suse.de>
    Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
    Cc: stable <stable@kernel.org>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
    83db93f4
file.c 19.2 KB