pktgen: allow faster module unload

Unloading pktgen module needs ~6 seconds on a 64 cpus machine, to stop
64 kthreads.

Add a pktgen_exiting variable to let kernel threads die faster, so that
kthread_stop() doesnt have to wait too long for them. This variable is
not tested in fast path.

Note : Before exiting from pktgen_thread_worker(), we must make sure
kthread_stop() is waiting for this thread to be stopped, like its done
in kernel/softirq.c

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 12 insertions, 5 deletions

diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 52fc1e08a7c4..2e57830cbeb2 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -395,6 +395,8 @@ struct pktgen_hdr {
         __be32 tv_usec;
 };
 
+static bool pktgen_exiting __read_mostly;
+
 struct pktgen_thread {
         spinlock_t if_lock;             /* for list of devices */
         struct list_head if_list;       /* All device here */
@@ -3451,11 +3453,6 @@ static void pktgen_rem_thread(struct pktgen_thread *t)
 
         remove_proc_entry(t->tsk->comm, pg_proc_dir);
 
-        mutex_lock(&pktgen_thread_lock);
-
-        list_del(&t->th_list);
-
-        mutex_unlock(&pktgen_thread_lock);
 }
 
 static void pktgen_resched(struct pktgen_dev *pkt_dev)
@@ -3602,6 +3599,8 @@ static int pktgen_thread_worker(void *arg)
                 pkt_dev = next_to_run(t);
 
                 if (unlikely(!pkt_dev && t->control == 0)) {
+                        if (pktgen_exiting)
+                                break;
                         wait_event_interruptible_timeout(t->queue,
                                                          t->control != 0,
                                                          HZ/10);
@@ -3654,6 +3653,13 @@ static int pktgen_thread_worker(void *arg)
         pr_debug("%s removing thread\n", t->tsk->comm);
         pktgen_rem_thread(t);
 
+        /* Wait for kthread_stop */
+        while (!kthread_should_stop()) {
+                set_current_state(TASK_INTERRUPTIBLE);
+                schedule();
+        }
+        __set_current_state(TASK_RUNNING);
+
         return 0;
 }
 
@@ -3928,6 +3934,7 @@ static void __exit pg_cleanup(void)
         struct list_head *q, *n;
 
         /* Stop all interfaces & threads */
+        pktgen_exiting = true;
 
         list_for_each_safe(q, n, &pktgen_threads) {
                 t = list_entry(q, struct pktgen_thread, th_list);