From: Oleg Drokin I think it would be nice to put an usage warning in header of lookup_instantiate_filp() to indicate it is unsafe to use it on anything but regular files (even that is potentially unsafe, but there your ->open() is usually in your hands anyway), so that others won't fall into the same trap I did. Signed-off-by: Oleg Drokin Cc: Trond Myklebust Signed-off-by: Andrew Morton --- fs/open.c | 4 ++++ 1 files changed, 4 insertions(+) diff -puN fs/open.c~add-lookup_instantiate_filp-usage-warning fs/open.c --- devel/fs/open.c~add-lookup_instantiate_filp-usage-warning 2006-03-11 02:46:54.000000000 -0800 +++ devel-akpm/fs/open.c 2006-03-11 02:46:54.000000000 -0800 @@ -896,6 +896,10 @@ EXPORT_SYMBOL(filp_open); * a fully instantiated struct file to the caller. * This function is meant to be called from within a filesystem's * lookup method. + * Beware of calling it for non-regular files! Those ->open methods might block + * (e.g. in fifo_open), leaving you with parent locked (and in case of fifo, + * leading to a deadlock, as nobody can open that fifo anymore, because + * another process to open fifo will block on locked parent when doing lookup). * Note that in case of error, nd->intent.open.file is destroyed, but the * path information remains valid. * If the open callback is set to NULL, then the standard f_op->open() _