From: Oleg Drokin Date: Sat, 25 Mar 2006 11:07:02 +0000 (-0800) Subject: [PATCH] Add lookup_instantiate_filp usage warning X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=9a56c213929d83139fd1e12727e1037d71b519f8;p=openwrt%2Fstaging%2Fblogic.git [PATCH] Add lookup_instantiate_filp usage warning 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 Signed-off-by: Linus Torvalds --- diff --git a/fs/open.c b/fs/open.c index 1091dadd6c38..7d02d19bd0a2 100644 --- a/fs/open.c +++ b/fs/open.c @@ -890,6 +890,10 @@ 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()