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authorJulian Wiedmann <jwi@linux.ibm.com>2019-08-12 16:44:35 +0200
committerJakub Kicinski <jakub.kicinski@netronome.com>2019-08-13 19:26:47 -0700
commit072f79400032f74917726cf76f4248367ea2b5b8 (patch)
tree7e4f8f96847681fe921c7f38067c464c8a2f4498 /drivers/s390
parenta1794de8b92ea6bc2037f445b296814ac826693e (diff)
s390/qeth: serialize cmd reply with concurrent timeout
Callbacks for a cmd reply run outside the protection of card->lock, to allow for additional cmds to be issued & enqueued in parallel. When qeth_send_control_data() bails out for a cmd without having received a reply (eg. due to timeout), its callback may concurrently be processing a reply that just arrived. In this case, the callback potentially accesses a stale reply->reply_param area that eg. was on-stack and has already been released. To avoid this race, add some locking so that qeth_send_control_data() can (1) wait for a concurrently running callback, and (2) zap any pending callback that still wants to run. Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com> Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Diffstat (limited to 'drivers/s390')
-rw-r--r--drivers/s390/net/qeth_core.h1
-rw-r--r--drivers/s390/net/qeth_core_main.c20
2 files changed, 21 insertions, 0 deletions
diff --git a/drivers/s390/net/qeth_core.h b/drivers/s390/net/qeth_core.h
index c7ee07ce3615..28db887d38ed 100644
--- a/drivers/s390/net/qeth_core.h
+++ b/drivers/s390/net/qeth_core.h
@@ -629,6 +629,7 @@ struct qeth_seqno {
struct qeth_reply {
struct list_head list;
struct completion received;
+ spinlock_t lock;
int (*callback)(struct qeth_card *, struct qeth_reply *,
unsigned long);
u32 seqno;
diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
index 4d0caeebc802..9c3310c4d61d 100644
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -544,6 +544,7 @@ static struct qeth_reply *qeth_alloc_reply(struct qeth_card *card)
if (reply) {
refcount_set(&reply->refcnt, 1);
init_completion(&reply->received);
+ spin_lock_init(&reply->lock);
}
return reply;
}
@@ -799,6 +800,13 @@ static void qeth_issue_next_read_cb(struct qeth_card *card,
if (!reply->callback) {
rc = 0;
+ goto no_callback;
+ }
+
+ spin_lock_irqsave(&reply->lock, flags);
+ if (reply->rc) {
+ /* Bail out when the requestor has already left: */
+ rc = reply->rc;
} else {
if (cmd) {
reply->offset = (u16)((char *)cmd - (char *)iob->data);
@@ -807,7 +815,9 @@ static void qeth_issue_next_read_cb(struct qeth_card *card,
rc = reply->callback(card, reply, (unsigned long)iob);
}
}
+ spin_unlock_irqrestore(&reply->lock, flags);
+no_callback:
if (rc <= 0)
qeth_notify_reply(reply, rc);
qeth_put_reply(reply);
@@ -1749,6 +1759,16 @@ static int qeth_send_control_data(struct qeth_card *card,
rc = (timeout == -ERESTARTSYS) ? -EINTR : -ETIME;
qeth_dequeue_reply(card, reply);
+
+ if (reply_cb) {
+ /* Wait until the callback for a late reply has completed: */
+ spin_lock_irq(&reply->lock);
+ if (rc)
+ /* Zap any callback that's still pending: */
+ reply->rc = rc;
+ spin_unlock_irq(&reply->lock);
+ }
+
if (!rc)
rc = reply->rc;
qeth_put_reply(reply);