From 17666497fe631fef483afd38824c5dabdd764b90 Mon Sep 17 00:00:00 2001 From: Ulf Magnusson Date: Mon, 7 Sep 2015 19:06:14 +0200 Subject: sysfs.txt: mention that store method buffers are null-terminated Without knowing this, the use of sysfs_streq() becomes puzzling. The termination happens in kernfs_fop_write(). Signed-off-by: Ulf Magnusson [jc: moved the new text to a different paragraph] Signed-off-by: Jonathan Corbet --- Documentation/filesystems/sysfs.txt | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/Documentation/filesystems/sysfs.txt b/Documentation/filesystems/sysfs.txt index 78170ed7bfde..24da7b32c489 100644 --- a/Documentation/filesystems/sysfs.txt +++ b/Documentation/filesystems/sysfs.txt @@ -191,9 +191,10 @@ implementations: be called again, rearmed, to fill the buffer. - On write(2), sysfs expects the entire buffer to be passed during the - first write. Sysfs then passes the entire buffer to the store() - method. - + first write. Sysfs then passes the entire buffer to the store() method. + A terminating null is added after the data on stores. This makes + functions like sysfs_streq() safe to use. + When writing sysfs files, userspace processes should first read the entire file, modify the values it wishes to change, then write the entire buffer back. -- cgit v1.2.3