[PATCH -repost 10/21] kgr: kthreads support

From: Jiri Slaby
Date: Wed Jun 25 2014 - 07:11:04 EST


Wake up kthreads so that they cycle through kgr_task_safe either
by an explicit call to it or implicitly via try_to_freeze. This
ensures nobody should use the old version of the code and kgraft core
can push everybody to use the new version by switching to the fast
path.

Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/kgraft.c | 27 ++++++++++++++++-----------
1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/kernel/kgraft.c b/kernel/kgraft.c
index b0c712e8297c..d21eaad8d48d 100644
--- a/kernel/kgraft.c
+++ b/kernel/kgraft.c
@@ -53,7 +53,7 @@ static void kgr_stub_slow(unsigned long ip, unsigned long parent_ip,
{
struct kgr_loc_caches *c = ops->private;

- if (kgr_task_in_progress(current) && current->mm) {
+ if (kgr_task_in_progress(current)) {
pr_info("kgr: slow stub: calling old code at %lx\n",
c->old);
kgr_set_regs_ip(regs, c->old + MCOUNT_INSN_SIZE);
@@ -71,11 +71,7 @@ static bool kgr_still_patching(void)

read_lock(&tasklist_lock);
for_each_process(p) {
- /*
- * TODO
- * kernel thread codepaths not supported and silently ignored
- */
- if (kgr_task_in_progress(p) && p->mm) {
+ if (kgr_task_in_progress(p)) {
pr_info("pid %d (%s) still in kernel after timeout\n",
p->pid, p->comm);
failed = true;
@@ -123,13 +119,23 @@ static void kgr_work_fn(struct work_struct *work)
mutex_unlock(&kgr_in_progress_lock);
}

-static void kgr_mark_processes(void)
+static void kgr_handle_processes(void)
{
struct task_struct *p;

read_lock(&tasklist_lock);
- for_each_process(p)
+ for_each_process(p) {
kgr_mark_task_in_progress(p);
+
+ /* wake up kthreads, they will clean the progress flag */
+ if (!p->mm) {
+ /*
+ * this is incorrect for kthreads waiting still for
+ * their first wake_up.
+ */
+ wake_up_process(p);
+ }
+ }
read_unlock(&tasklist_lock);
}

@@ -274,8 +280,7 @@ static int kgr_patch_code(const struct kgr_patch_fun *patch_fun, bool final)
* kgr_start_patching -- the entry for a kgraft patch
* @patch: patch to be applied
*
- * Start patching of code that is neither running in IRQ context nor
- * kernel thread.
+ * Start patching of code that is not running in IRQ context.
*/
int kgr_start_patching(const struct kgr_patch *patch)
{
@@ -314,7 +319,7 @@ int kgr_start_patching(const struct kgr_patch *patch)
kgr_patch = patch;
mutex_unlock(&kgr_in_progress_lock);

- kgr_mark_processes();
+ kgr_handle_processes();

/*
* give everyone time to exit kernel, and check after a while
--
2.0.0

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