[PATCH v3 14/15] livepatch: add /proc//patch_state

Josh Poimboeuf
2016-12-08T18:08:39Z

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 <jpoimboe@redhat.com>
---
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.
+

------------------------------------------------------------------------------
Configuring procfs
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 5ea8363..2e1e012 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2841,6 +2841,15 @@ static int proc_pid_personality(struct seq_file *m, struct pid_namespace *ns,
return err;
}

+#ifdef CONFIG_LIVEPATCH
+static int proc_pid_patch_state(struct seq_file *m, struct pid_namespace *ns,
+ struct pid *pid, struct task_struct *task)
+{
+ seq_printf(m, "%d\n", task->patch_state);
+ return 0;
+}
+#endif /* CONFIG_LIVEPATCH */
+
/*
* Thread groups
*/
@@ -2940,6 +2949,9 @@ static const struct pid_entry tgid_base_stuff[] = {
REG("timers", S_IRUGO, proc_timers_operations),
#endif
REG("timerslack_ns", S_IRUGO|S_IWUGO, proc_pid_set_timerslack_ns_operations),
+#ifdef CONFIG_LIVEPATCH
+ ONE("patch_state", S_IRUSR, proc_pid_patch_state),
+#endif
};

static int proc_tgid_base_readdir(struct file *file, struct dir_context *ctx)
@@ -3320,6 +3332,9 @@ static const struct pid_entry tid_base_stuff[] = {
REG("projid_map", S_IRUGO|S_IWUSR, proc_projid_map_operations),
REG("setgroups", S_IRUGO|S_IWUSR, proc_setgroups_operations),
#endif
+#ifdef CONFIG_LIVEPATCH
+ ONE("patch_state", S_IRUSR, proc_pid_patch_state),
+#endif
};

static int proc_tid_base_readdir(struct file *file, struct dir_context *ctx)
--
2.7.4