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>

diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 52fc1e08a7c47d2a2d09e546d817e312c7d337cb..2e57830cbeb2e56a04f0f34449f3eebf31515207 100644 (file)
--- 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);