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authorOleg Drokin <green@linuxhacker.ru>2006-03-25 03:07:02 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-03-25 08:22:51 -0800
commit9a56c213929d83139fd1e12727e1037d71b519f8 (patch)
tree013dd77c7cae23bd8fb821175a0d6fdc35bad9fe
parentb500531e6f5f234ed267bd7060ee06d144faf0ca (diff)
[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 <green@linuxhacker.ru> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--fs/open.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/fs/open.c b/fs/open.c
index 1091dadd6c3..7d02d19bd0a 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()