On Thu, 19 Jan 2017, Josh Poimboeuf wrote:
quoted hunk ↗ jump to hunk
Expose the per-task patch state value so users can determine which tasks
are holding up completion of a patching operation.
Signed-off-by: Josh Poimboeuf <redacted>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
---
Documentation/filesystems/proc.txt | 18 ++++++++++++++++++
fs/proc/base.c | 15 +++++++++++++++
2 files changed, 33 insertions(+)
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index 72624a1..85c501b 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -44,6 +44,7 @@ Table of Contents
3.8 /proc/<pid>/fdinfo/<fd> - Information about opened file
3.9 /proc/<pid>/map_files - Information about memory mapped files
3.10 /proc/<pid>/timerslack_ns - Task timerslack value
+ 3.11 /proc/<pid>/patch_state - Livepatch patch operation state
4 Configuring procfs
4.1 Mount options
@@ -1886,6 +1887,23 @@ Valid values are from 0 - ULLONG_MAX
An application setting the value must have PTRACE_MODE_ATTACH_FSCREDS level
permissions on the task specified to change its timerslack_ns value.
+3.11 /proc/<pid>/patch_state - Livepatch patch operation state
+-----------------------------------------------------------------
+When CONFIG_LIVEPATCH is enabled, this file displays the value of the
+patch state for the task.
+
+A value of '-1' indicates that no patch is in transition.
+
+A value of '0' indicates that a patch is in transition and the task is
+unpatched. If the patch is being enabled, then the task hasn't been
+patched yet. If the patch is being disabled, then the task has already
+been unpatched.
+
+A value of '1' indicates that a patch is in transition and the task is
+patched. If the patch is being enabled, then the task has already been
+patched. If the patch is being disabled, then the task hasn't been
+unpatched yet.
+
Despite my review I thought about this some more. I think the logic make
sense internally but when exposed it can be confusing. We do not export
klp_target_state value, so users have to know if a patch is being enabled
or disabled. Of course, they should know that, but I guess they'd like to
use an userspace tool for this. Such tool needs to look at
/proc/<pid>/patch_state to find out which tasks are blocking the
completion and that is it. No more information anywhere.
We can either export klp_target_state, or change /proc/<pid>/patch_state
to show only two states - task is in transition (1), task is patched (0).
What do you think?
Miroslav