[patch 58/86] vhost, kcov: collect coverage from vhost_worker

Andrew Morton
2019-12-05T00:52:53Z

From: Andrey Konovalov <andreyknvl@google.com>
Subject: vhost, kcov: collect coverage from vhost_worker

Add kcov_remote_start()/kcov_remote_stop() annotations to the
vhost_worker() function, which is responsible for processing vhost works.
Since vhost_worker() threads are spawned per vhost device instance the
common kcov handle is used for kcov_remote_start()/stop() annotations (see
Documentation/dev-tools/kcov.rst for details). As the result kcov can now
be used to collect coverage from vhost worker threads.

Link: http://lkml.kernel.org/r/e49d5d154e5da6c9ada521d2b7ce10a49ce9f98b.1572366574.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Alexander Potapenko <glider@google.com>
Cc: Anders Roxell <anders.roxell@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David Windsor <dwindsor@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Elena Reshetova <elena.reshetova@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Marco Elver <elver@google.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

drivers/vhost/vhost.c | 6 ++++++
drivers/vhost/vhost.h | 1 +
2 files changed, 7 insertions(+)

--- a/drivers/vhost/vhost.c~vhost-kcov-collect-coverage-from-vhost_worker
+++ a/drivers/vhost/vhost.c
@@ -30,6 +30,7 @@
#include <linux/sched/signal.h>
#include <linux/interval_tree_generic.h>
#include <linux/nospec.h>
+#include <linux/kcov.h>

#include "vhost.h"

@@ -357,7 +358,9 @@ static int vhost_worker(void *data)
llist_for_each_entry_safe(work, work_next, node, node) {
clear_bit(VHOST_WORK_QUEUED, &work->flags);
__set_current_state(TASK_RUNNING);
+ kcov_remote_start_common(dev->kcov_handle);
work->fn(work);
+ kcov_remote_stop();
if (need_resched())
schedule();
}
@@ -546,6 +549,7 @@ long vhost_dev_set_owner(struct vhost_de

/* No owner, become one */
dev->mm = get_task_mm(current);
+ dev->kcov_handle = kcov_common_handle();
worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
if (IS_ERR(worker)) {
err = PTR_ERR(worker);
@@ -571,6 +575,7 @@ err_worker:
if (dev->mm)
mmput(dev->mm);
dev->mm = NULL;
+ dev->kcov_handle = 0;
err_mm:
return err;
}
@@ -682,6 +687,7 @@ void vhost_dev_cleanup(struct vhost_dev
if (dev->worker) {
kthread_stop(dev->worker);
dev->worker = NULL;
+ dev->kcov_handle = 0;
}
if (dev->mm)
mmput(dev->mm);
--- a/drivers/vhost/vhost.h~vhost-kcov-collect-coverage-from-vhost_worker
+++ a/drivers/vhost/vhost.h
@@ -173,6 +173,7 @@ struct vhost_dev {
int iov_limit;
int weight;
int byte_weight;
+ u64 kcov_handle;
};

bool vhost_exceeds_weight(struct vhost_virtqueue *vq, int pkts, int total_len);
_