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haven: msgq: Make the send/recv wait if the cap-id is not ready

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It's a highly likely situation that the clients call hh_msgq_recv()
from a thread in a polling fashion, and these threads are spawned
during client driver's initialization. Hence, it's possible that
the cap-ids for the message queues will not be ready so early and
the clients would end up continuously spinning on hh_msgq_recv(),
receiving the error -EAGAIN. To avoid this situation, put the
client process onto a wait-queue until the cap-ids are ready.

Although a little unlikely, to satisfy the symmetry, add the same
provision for the callers of hh_msgq_send() as well.

Change-Id: I4e042215c5e43271d566340ce1ef9c52ecafeb5c
Signed-off-by: Raghavendra Rao Ananta <rananta@codeaurora.org>
Signed-off-by: Murali Nalajala <mnalajal@codeaurora.org>
This commit is contained in:
Raghavendra Rao Ananta 2020-03-16 20:53:50 -07:00 • committed by Elliot Berman
commit 3aa6a08878
1 changed files with 42 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

48
drivers/virt/haven/hh_msgq.c
View file

@ -9,6 +9,7 @@
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/ratelimit.h>
#include <linux/haven/hcall.h>
#include <linux/haven/hh_msgq.h>
@ -40,6 +41,7 @@ struct hh_msgq_cap_table {
wait_queue_head_t rx_wq;
};
static bool hh_msgq_initialized;
static struct hh_msgq_cap_table hh_msgq_cap_table[HH_MSGQ_LABEL_MAX];
static irqreturn_t hh_msgq_rx_isr(int irq, void *dev)
@ -118,6 +120,9 @@ static int __hh_msgq_recv(struct hh_msgq_cap_table *cap_table_entry,
* if the message queue is not yet ready to communicate, and -EPERM if the
* caller doesn't have permissions to receive the data. 0 is the data is
* successfully received.
*
* Note: this function may sleep and should not be called from interrupt
* context
*/
int hh_msgq_recv(void *msgq_client_desc,
void **buff, size_t *size, unsigned long flags)
@ -139,15 +144,25 @@ int hh_msgq_recv(void *msgq_client_desc,
goto err;
}
if (cap_table_entry->rx_cap_id == HH_CAPID_INVAL) {
pr_err("%s: Recv info for label %d not yet initialized\n",
if ((cap_table_entry->rx_cap_id == HH_CAPID_INVAL) &&
(flags & HH_MSGQ_NONBLOCK)) {
pr_err_ratelimited(
"%s: Recv info for label %d not yet initialized\n",
__func__, client_desc->label);
ret = -EAGAIN;
goto err;
}
spin_unlock(&cap_table_entry->cap_entry_lock);
if (wait_event_interruptible(cap_table_entry->rx_wq,
cap_table_entry->rx_cap_id != HH_CAPID_INVAL))
return -ERESTARTSYS;
spin_lock(&cap_table_entry->cap_entry_lock);
if (!cap_table_entry->rx_irq) {
pr_err("%s: Rx IRQ for label %d not yet setup\n",
pr_err_ratelimited("%s: Rx IRQ for label %d not yet setup\n",
__func__, client_desc->label);
ret = -EAGAIN;
goto err;
@ -260,15 +275,25 @@ int hh_msgq_send(void *msgq_client_desc,
goto err;
}
if (cap_table_entry->tx_cap_id == HH_CAPID_INVAL) {
pr_err("%s: Send info for label %d not yet initialized\n",
if ((cap_table_entry->tx_cap_id == HH_CAPID_INVAL) &&
(flags & HH_MSGQ_NONBLOCK)) {
pr_err_ratelimited(
"%s: Send info for label %d not yet initialized\n",
__func__, client_desc->label);
ret = -EAGAIN;
goto err;
}
spin_unlock(&cap_table_entry->cap_entry_lock);
if (wait_event_interruptible(cap_table_entry->tx_wq,
cap_table_entry->tx_cap_id != HH_CAPID_INVAL))
return -ERESTARTSYS;
spin_lock(&cap_table_entry->cap_entry_lock);
if (!cap_table_entry->tx_irq) {
pr_err("%s: Tx IRQ for label %d not yet setup\n",
pr_err_ratelimited("%s: Tx IRQ for label %d not yet setup\n",
__func__, client_desc->label);
ret = -EAGAIN;
goto err;
@ -316,6 +341,9 @@ void *hh_msgq_register(enum hh_msgq_label label)
struct hh_msgq_cap_table *cap_table_entry;
struct hh_msgq_desc *client_desc;
if (!hh_msgq_initialized)
return ERR_PTR(-EPROBE_DEFER);
if (label < 0 || label >= HH_MSGQ_LABEL_MAX)
return ERR_PTR(-EINVAL);
@ -393,6 +421,9 @@ int hh_msgq_populate_cap_info(enum hh_msgq_label label, u64 cap_id,
struct hh_msgq_cap_table *cap_table_entry;
int ret;
if (!hh_msgq_initialized)
return -EPROBE_DEFER;
if (label < 0 || label >= HH_MSGQ_LABEL_MAX) {
pr_err("%s: Invalid label passed\n", __func__);
return -EINVAL;
@ -415,6 +446,8 @@ int hh_msgq_populate_cap_info(enum hh_msgq_label label, u64 cap_id,
cap_table_entry->tx_irq = irq;
cap_table_entry->tx_cap_id = cap_id;
wake_up_interruptible(&cap_table_entry->tx_wq);
} else if (direction == HH_MSGQ_DIRECTION_RX) {
ret = request_irq(irq, hh_msgq_rx_isr, 0,
cap_table_entry->rx_irq_name, cap_table_entry);
@ -423,6 +456,8 @@ int hh_msgq_populate_cap_info(enum hh_msgq_label label, u64 cap_id,
cap_table_entry->rx_cap_id = cap_id;
cap_table_entry->rx_irq = irq;
wake_up_interruptible(&cap_table_entry->rx_wq);
} else {
pr_err("%s: Invalid direction passed\n", __func__);
ret = -EINVAL;
@ -493,6 +528,7 @@ static int __init hh_msgq_init(void)
}
}
hh_msgq_initialized = true;
return 0;
err: