From bc6a0cbd576c66995d782331456f68ae63a50af4 Mon Sep 17 00:00:00 2001 From: Pavel Machek Date: Fri, 23 Apr 2010 20:32:29 +0200 Subject: [PATCH] PM / Hibernate: document open(/dev/snapshot) side effects Opening and closing /dev/snapshot causes the kernel to carry out some hibernate preparations that should be documented. [rjw: Added the changelog.] Signed-off-by: Pavel Machek Signed-off-by: Rafael J. Wysocki --- Documentation/power/userland-swsusp.txt | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/Documentation/power/userland-swsusp.txt b/Documentation/power/userland-swsusp.txt index b967cd9137d6..81680f9f5909 100644 --- a/Documentation/power/userland-swsusp.txt +++ b/Documentation/power/userland-swsusp.txt @@ -24,6 +24,10 @@ assumed to be in the resume mode. The device cannot be open for simultaneous reading and writing. It is also impossible to have the device open more than once at a time. +Even opening the device has side effects. Data structures are +allocated, and PM_HIBERNATION_PREPARE / PM_RESTORE_PREPARE chains are +called. + The ioctl() commands recognized by the device are: SNAPSHOT_FREEZE - freeze user space processes (the current process is