4.8-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ Upstream commit 9a0b1e8ba4061778897b544afc898de2163382f7 ]
After Jesper commit back in linux-3.18, we trigger a lockdep
splat in proc_create_data() while allocating memory from
pktgen_change_name().
This patch converts t->if_lock to a mutex, since it is now only
used from control path, and adds proper locking to pktgen_change_name()
1) pktgen_thread_lock to protect the outer loop (iterating threads)
2) t->if_lock to protect the inner loop (iterating devices)
Note that before Jesper patch, pktgen_change_name() was lacking proper
protection, but lockdep was not able to detect the problem.
Fixes: 8788370a1d4b ("pktgen: RCU-ify "if_list" to remove lock in next_to_run()")
Reported-by: John Sperbeck <jsperbeck@xxxxxxxxxx>
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/core/pktgen.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -216,8 +216,8 @@
#define M_QUEUE_XMIT 2 /* Inject packet into qdisc */
/* If lock -- protects updating of if_list */
-#define if_lock(t) spin_lock(&(t->if_lock));
-#define if_unlock(t) spin_unlock(&(t->if_lock));
+#define if_lock(t) mutex_lock(&(t->if_lock));
+#define if_unlock(t) mutex_unlock(&(t->if_lock));
/* Used to help with determining the pkts on receive */
#define PKTGEN_MAGIC 0xbe9be955
@@ -423,7 +423,7 @@ struct pktgen_net {
};
struct pktgen_thread {
- spinlock_t if_lock; /* for list of devices */
+ struct mutex if_lock; /* for list of devices */
struct list_head if_list; /* All device here */
struct list_head th_list;
struct task_struct *tsk;
@@ -2010,11 +2010,13 @@ static void pktgen_change_name(const str
{
struct pktgen_thread *t;
+ mutex_lock(&pktgen_thread_lock);
+
list_for_each_entry(t, &pn->pktgen_threads, th_list) {
struct pktgen_dev *pkt_dev;
- rcu_read_lock();
- list_for_each_entry_rcu(pkt_dev, &t->if_list, list) {
+ if_lock(t);
+ list_for_each_entry(pkt_dev, &t->if_list, list) {
if (pkt_dev->odev != dev)
continue;
@@ -2029,8 +2031,9 @@ static void pktgen_change_name(const str
dev->name);
break;
}
- rcu_read_unlock();
+ if_unlock(t);
}
+ mutex_unlock(&pktgen_thread_lock);
}
static int pktgen_device_event(struct notifier_block *unused,
@@ -3762,7 +3765,7 @@ static int __net_init pktgen_create_thre
return -ENOMEM;
}
- spin_lock_init(&t->if_lock);
+ mutex_init(&t->if_lock);
t->cpu = cpu;
INIT_LIST_HEAD(&t->if_list);
--
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