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s390/qeth: simplify reply object handling
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Current code enqueues & dequeues a reply object from the waiter list
in various places. In particular, the dequeue & enqueue in
qeth_send_control_data_cb() looks fragile - this can cause
qeth_clear_ipacmd_list() to skip the active object.
Add some helpers, and boil the logic down by giving
qeth_send_control_data() the sole responsibility to add and remove
objects.

qeth_send_control_data_cb() and qeth_clear_ipacmd_list() will now only
notify the reply object to interrupt its wait cycle. This can cause
a slight delay in the removal, but that's no concern.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Julian Wiedmann authored and David S. Miller committed Feb 12, 2019
1 parent 51581fd commit 0951c6b
Showing 1 changed file with 61 additions and 57 deletions.
118 changes: 61 additions & 57 deletions drivers/s390/net/qeth_core_main.c
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Original file line number Diff line number Diff line change
Expand Up @@ -566,6 +566,7 @@ static struct qeth_reply *qeth_alloc_reply(struct qeth_card *card)
if (reply) {
refcount_set(&reply->refcnt, 1);
atomic_set(&reply->received, 0);
init_waitqueue_head(&reply->wait_q);
}
return reply;
}
Expand All @@ -581,6 +582,26 @@ static void qeth_put_reply(struct qeth_reply *reply)
kfree(reply);
}

static void qeth_enqueue_reply(struct qeth_card *card, struct qeth_reply *reply)
{
spin_lock_irq(&card->lock);
list_add_tail(&reply->list, &card->cmd_waiter_list);
spin_unlock_irq(&card->lock);
}

static void qeth_dequeue_reply(struct qeth_card *card, struct qeth_reply *reply)
{
spin_lock_irq(&card->lock);
list_del(&reply->list);
spin_unlock_irq(&card->lock);
}

static void qeth_notify_reply(struct qeth_reply *reply)
{
atomic_inc(&reply->received);
wake_up(&reply->wait_q);
}

static void qeth_issue_ipa_msg(struct qeth_ipa_cmd *cmd, int rc,
struct qeth_card *card)
{
Expand Down Expand Up @@ -657,19 +678,15 @@ static struct qeth_ipa_cmd *qeth_check_ipa_data(struct qeth_card *card,

void qeth_clear_ipacmd_list(struct qeth_card *card)
{
struct qeth_reply *reply, *r;
struct qeth_reply *reply;
unsigned long flags;

QETH_CARD_TEXT(card, 4, "clipalst");

spin_lock_irqsave(&card->lock, flags);
list_for_each_entry_safe(reply, r, &card->cmd_waiter_list, list) {
qeth_get_reply(reply);
list_for_each_entry(reply, &card->cmd_waiter_list, list) {
reply->rc = -EIO;
atomic_inc(&reply->received);
list_del_init(&reply->list);
wake_up(&reply->wait_q);
qeth_put_reply(reply);
qeth_notify_reply(reply);
}
spin_unlock_irqrestore(&card->lock, flags);
}
Expand Down Expand Up @@ -774,9 +791,10 @@ static void qeth_send_control_data_cb(struct qeth_card *card,
struct qeth_cmd_buffer *iob)
{
struct qeth_ipa_cmd *cmd = NULL;
struct qeth_reply *reply, *r;
struct qeth_reply *reply = NULL;
struct qeth_reply *r;
unsigned long flags;
int keep_reply;
int keep_reply = 0;
int rc = 0;

QETH_CARD_TEXT(card, 4, "sndctlcb");
Expand Down Expand Up @@ -808,44 +826,40 @@ static void qeth_send_control_data_cb(struct qeth_card *card,
goto out;
}

/* match against pending cmd requests */
spin_lock_irqsave(&card->lock, flags);
list_for_each_entry_safe(reply, r, &card->cmd_waiter_list, list) {
if ((reply->seqno == QETH_IDX_COMMAND_SEQNO) ||
((cmd) && (reply->seqno == cmd->hdr.seqno))) {
list_for_each_entry(r, &card->cmd_waiter_list, list) {
if ((r->seqno == QETH_IDX_COMMAND_SEQNO) ||
(cmd && (r->seqno == cmd->hdr.seqno))) {
reply = r;
/* take the object outside the lock */
qeth_get_reply(reply);
list_del_init(&reply->list);
spin_unlock_irqrestore(&card->lock, flags);
keep_reply = 0;
if (reply->callback != NULL) {
if (cmd) {
reply->offset = (__u16)((char *)cmd -
(char *)iob->data);
keep_reply = reply->callback(card,
reply,
(unsigned long)cmd);
} else
keep_reply = reply->callback(card,
reply,
(unsigned long)iob);
}
if (cmd)
reply->rc = (u16) cmd->hdr.return_code;
else if (iob->rc)
reply->rc = iob->rc;
if (keep_reply) {
spin_lock_irqsave(&card->lock, flags);
list_add_tail(&reply->list,
&card->cmd_waiter_list);
spin_unlock_irqrestore(&card->lock, flags);
} else {
atomic_inc(&reply->received);
wake_up(&reply->wait_q);
}
qeth_put_reply(reply);
goto out;
break;
}
}
spin_unlock_irqrestore(&card->lock, flags);

if (!reply)
goto out;

if (reply->callback) {
if (cmd) {
reply->offset = (u16)((char *)cmd - (char *)iob->data);
keep_reply = reply->callback(card, reply,
(unsigned long)cmd);
} else
keep_reply = reply->callback(card, reply,
(unsigned long)iob);
}
if (cmd)
reply->rc = (u16) cmd->hdr.return_code;
else if (iob->rc)
reply->rc = iob->rc;

if (!keep_reply)
qeth_notify_reply(reply);
qeth_put_reply(reply);

out:
memcpy(&card->seqno.pdu_hdr_ack,
QETH_PDU_HEADER_SEQ_NO(iob->data),
Expand Down Expand Up @@ -2047,8 +2061,6 @@ static int qeth_send_control_data(struct qeth_card *card, int len,
reply->callback = reply_cb;
reply->param = reply_param;

init_waitqueue_head(&reply->wait_q);

while (atomic_cmpxchg(&channel->irq_pending, 0, 1)) ;

if (IS_IPA(iob->data)) {
Expand All @@ -2062,9 +2074,7 @@ static int qeth_send_control_data(struct qeth_card *card, int len,
}
qeth_prepare_control_data(card, len, iob);

spin_lock_irq(&card->lock);
list_add_tail(&reply->list, &card->cmd_waiter_list);
spin_unlock_irq(&card->lock);
qeth_enqueue_reply(card, reply);

timeout = jiffies + event_timeout;

Expand All @@ -2077,10 +2087,8 @@ static int qeth_send_control_data(struct qeth_card *card, int len,
QETH_DBF_MESSAGE(2, "qeth_send_control_data on device %x: ccw_device_start rc = %i\n",
CARD_DEVID(card), rc);
QETH_CARD_TEXT_(card, 2, " err%d", rc);
spin_lock_irq(&card->lock);
list_del_init(&reply->list);
qeth_dequeue_reply(card, reply);
qeth_put_reply(reply);
spin_unlock_irq(&card->lock);
qeth_release_buffer(channel, iob);
atomic_set(&channel->irq_pending, 0);
wake_up(&card->wait_q);
Expand All @@ -2102,19 +2110,15 @@ static int qeth_send_control_data(struct qeth_card *card, int len,
}
}

qeth_dequeue_reply(card, reply);
rc = reply->rc;
qeth_put_reply(reply);
return rc;

time_err:
reply->rc = -ETIME;
spin_lock_irq(&card->lock);
list_del_init(&reply->list);
spin_unlock_irq(&card->lock);
atomic_inc(&reply->received);
rc = reply->rc;
qeth_dequeue_reply(card, reply);
qeth_put_reply(reply);
return rc;
return -ETIME;
}

static int qeth_cm_enable_cb(struct qeth_card *card, struct qeth_reply *reply,
Expand Down

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