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Commit 3aa6a088 authored by Raghavendra Rao Ananta's avatar Raghavendra Rao Ananta Committed by Elliot Berman
Browse files

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



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: default avatarRaghavendra Rao Ananta <rananta@codeaurora.org>
Signed-off-by: default avatarMurali Nalajala <mnalajal@codeaurora.org>
parent eb5a7871

drivers/virt/haven/hh_msgq.c

+42 −6
Original line number Diff line number Diff line
@@ -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: