Commit 5015115d authored by Bryan O'Donoghue's avatar Bryan O'Donoghue Committed by Greg Kroah-Hartman
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greybus: loopback: sort list of connections for masking purposes 



In user-space we specify a list of connections as a bit-mask with the
assumption that a list such is indexed as indicated below.

end0:3:3:1:1 = 1
end0:3:3:2:3 = 2
end0:3:3:3:4 = 4

Current code assigns bitmask ids based on the order of discovery, however
user-space has no idea what the order of discovery is. This patch sorts the
linked list of connections associated with the loopback driver and assigns
a bit-id based on the sorted list - not the order of discovery. This
change therefore enforces the end-users idea that end0:3:3:1:1 above is
always denoted by bit 1 - even if from the AP's perspective it was the last
entry discovered.

Signed-off-by: default avatarBryan O'Donoghue <bryan.odonoghue@linaro.org>
Reviewed-by: default avatarPatrick Titiano <ptitiano@baylibre.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@google.com>
parent 4a655ad4

drivers/staging/greybus/loopback.c

+46 −2
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
#include <linux/fs.h>

#include <linux/kfifo.h>

#include <linux/debugfs.h>

#include <linux/list_sort.h>



#include <asm/div64.h>
@@ -843,6 +844,50 @@ static const struct file_operations gb_loopback_debugfs_dev_latency_ops = { 
	.release	= single_release,

};



static int gb_loopback_bus_id_compare(void *priv, struct list_head *lha,

				      struct list_head *lhb)

{

	struct gb_loopback *a = list_entry(lha, struct gb_loopback, entry);

	struct gb_loopback *b = list_entry(lhb, struct gb_loopback, entry);

	struct gb_connection *ca = a->connection;

	struct gb_connection *cb = b->connection;



	if (ca->bundle->intf->module->module_id <

	    cb->bundle->intf->module->module_id)

		return -1;

	if (cb->bundle->intf->module->module_id <

	    ca->bundle->intf->module->module_id)

		return 1;

	if (ca->bundle->intf->interface_id < cb->bundle->intf->interface_id)

		return -1;

	if (cb->bundle->intf->interface_id < ca->bundle->intf->interface_id)

		return 1;

	if (ca->bundle->id < cb->bundle->id)

		return -1;

	if (cb->bundle->id < ca->bundle->id)

		return 1;

	if (ca->intf_cport_id < cb->intf_cport_id)

		return -1;

	else if (cb->intf_cport_id < ca->intf_cport_id)

		return 1;



	return 0;

}



static void gb_loopback_insert_id(struct gb_loopback *gb)

{

	struct gb_loopback *gb_list;

	u32 new_lbid = 0;



	/* perform an insertion sort */

	list_add_tail(&gb->entry, &gb_dev.list);

	list_sort(NULL, &gb_dev.list, gb_loopback_bus_id_compare);

	list_for_each_entry(gb_list, &gb_dev.list, entry) {

		gb_list->lbid = 1 << new_lbid;

		new_lbid++;

	}

}



#define DEBUGFS_NAMELEN 32



static int gb_loopback_connection_init(struct gb_connection *connection)
@@ -908,14 +953,13 @@ static int gb_loopback_connection_init(struct gb_connection *connection) 


	/* Fork worker thread */

	mutex_init(&gb->mutex);

	gb->lbid = 1 << gb_dev.count;

	gb->task = kthread_run(gb_loopback_fn, gb, "gb_loopback");

	if (IS_ERR(gb->task)) {

		retval = PTR_ERR(gb->task);

		goto out_kfifo1;

	}



	list_add_tail(&gb->entry, &gb_dev.list);

	gb_loopback_insert_id(gb);

	gb_dev.count++;

	mutex_unlock(&gb_dev.mutex);

	return 0;