Commit 0b1e9738 authored by sjur.brandeland@stericsson.com's avatar sjur.brandeland@stericsson.com Committed by David S. Miller
Browse files

caif: Use rcu_read_lock in CAIF mux layer. 



Replace spin_lock with rcu_read_lock when accessing lists to layers
and cache. While packets are in flight rcu_read_lock should not be held,
instead ref-counters are used in combination with RCU.

Signed-off-by: default avatarSjur Brændeland <sjur.brandeland@stericsson.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1b1cb1f7

include/net/caif/cffrml.h

+2 −0
Original line number Diff line number Diff line
@@ -12,5 +12,7 @@ struct cffrml; 
struct cflayer *cffrml_create(u16 phyid, bool DoFCS);

void cffrml_set_uplayer(struct cflayer *this, struct cflayer *up);

void cffrml_set_dnlayer(struct cflayer *this, struct cflayer *dn);

void cffrml_put(struct cflayer *layr);

void cffrml_hold(struct cflayer *layr);



#endif /* CFFRML_H_ */

net/caif/cffrml.c

+8 −0
Original line number Diff line number Diff line
@@ -145,3 +145,11 @@ static void cffrml_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl, 
	if (layr->up->ctrlcmd)

		layr->up->ctrlcmd(layr->up, ctrl, layr->id);

}



void cffrml_put(struct cflayer *layr)

{

}



void cffrml_hold(struct cflayer *layr)

{

}

net/caif/cfmuxl.c

+75 −44
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ 
#include <linux/stddef.h>

#include <linux/spinlock.h>

#include <linux/slab.h>

#include <linux/rculist.h>

#include <net/caif/cfpkt.h>

#include <net/caif/cfmuxl.h>

#include <net/caif/cfsrvl.h>
@@ -64,31 +65,31 @@ struct cflayer *cfmuxl_create(void) 
int cfmuxl_set_uplayer(struct cflayer *layr, struct cflayer *up, u8 linkid)

{

	struct cfmuxl *muxl = container_obj(layr);

	spin_lock(&muxl->receive_lock);

	cfsrvl_get(up);

	list_add(&up->node, &muxl->srvl_list);

	spin_unlock(&muxl->receive_lock);



	spin_lock_bh(&muxl->receive_lock);

	list_add_rcu(&up->node, &muxl->srvl_list);

	spin_unlock_bh(&muxl->receive_lock);

	return 0;

}



int cfmuxl_set_dnlayer(struct cflayer *layr, struct cflayer *dn, u8 phyid)

{

	struct cfmuxl *muxl = (struct cfmuxl *) layr;

	spin_lock(&muxl->transmit_lock);

	list_add(&dn->node, &muxl->frml_list);

	spin_unlock(&muxl->transmit_lock);



	spin_lock_bh(&muxl->transmit_lock);

	list_add_rcu(&dn->node, &muxl->frml_list);

	spin_unlock_bh(&muxl->transmit_lock);

	return 0;

}



static struct cflayer *get_from_id(struct list_head *list, u16 id)

{

	struct list_head *node;

	struct cflayer *layer;

	list_for_each(node, list) {

		layer = list_entry(node, struct cflayer, node);

		if (layer->id == id)

			return layer;

	struct cflayer *lyr;

	list_for_each_entry_rcu(lyr, list, node) {

		if (lyr->id == id)

			return lyr;

	}



	return NULL;

}
@@ -96,41 +97,45 @@ struct cflayer *cfmuxl_remove_dnlayer(struct cflayer *layr, u8 phyid) 
{

	struct cfmuxl *muxl = container_obj(layr);

	struct cflayer *dn;

	spin_lock(&muxl->transmit_lock);

	memset(muxl->dn_cache, 0, sizeof(muxl->dn_cache));

	int idx = phyid % DN_CACHE_SIZE;



	spin_lock_bh(&muxl->transmit_lock);

	rcu_assign_pointer(muxl->dn_cache[idx], NULL);

	dn = get_from_id(&muxl->frml_list, phyid);

	if (dn == NULL) {

		spin_unlock(&muxl->transmit_lock);

		return NULL;

	}

	list_del(&dn->node);

	if (dn == NULL)

		goto out;



	list_del_rcu(&dn->node);

	caif_assert(dn != NULL);

	spin_unlock(&muxl->transmit_lock);

out:

	spin_unlock_bh(&muxl->transmit_lock);

	return dn;

}



/* Invariant: lock is taken */

static struct cflayer *get_up(struct cfmuxl *muxl, u16 id)

{

	struct cflayer *up;

	int idx = id % UP_CACHE_SIZE;

	up = muxl->up_cache[idx];

	up = rcu_dereference(muxl->up_cache[idx]);

	if (up == NULL || up->id != id) {

		spin_lock_bh(&muxl->receive_lock);

		up = get_from_id(&muxl->srvl_list, id);

		muxl->up_cache[idx] = up;

		rcu_assign_pointer(muxl->up_cache[idx], up);

		spin_unlock_bh(&muxl->receive_lock);

	}

	return up;

}



/* Invariant: lock is taken */

static struct cflayer *get_dn(struct cfmuxl *muxl, struct dev_info *dev_info)

{

	struct cflayer *dn;

	int idx = dev_info->id % DN_CACHE_SIZE;

	dn = muxl->dn_cache[idx];

	dn = rcu_dereference(muxl->dn_cache[idx]);

	if (dn == NULL || dn->id != dev_info->id) {

		spin_lock_bh(&muxl->transmit_lock);

		dn = get_from_id(&muxl->frml_list, dev_info->id);

		muxl->dn_cache[idx] = dn;

		rcu_assign_pointer(muxl->dn_cache[idx], dn);

		spin_unlock_bh(&muxl->transmit_lock);

	}

	return dn;

}
@@ -139,15 +144,17 @@ struct cflayer *cfmuxl_remove_uplayer(struct cflayer *layr, u8 id) 
{

	struct cflayer *up;

	struct cfmuxl *muxl = container_obj(layr);

	spin_lock(&muxl->receive_lock);

	up = get_up(muxl, id);

	int idx = id % UP_CACHE_SIZE;



	spin_lock_bh(&muxl->receive_lock);

	up = get_from_id(&muxl->srvl_list, id);

	if (up == NULL)

		goto out;

	memset(muxl->up_cache, 0, sizeof(muxl->up_cache));

	list_del(&up->node);

	cfsrvl_put(up);



	rcu_assign_pointer(muxl->up_cache[idx], NULL);

	list_del_rcu(&up->node);

out:

	spin_unlock(&muxl->receive_lock);

	spin_unlock_bh(&muxl->receive_lock);

	return up;

}
@@ -162,22 +169,28 @@ static int cfmuxl_receive(struct cflayer *layr, struct cfpkt *pkt) 
		cfpkt_destroy(pkt);

		return -EPROTO;

	}



	spin_lock(&muxl->receive_lock);

	rcu_read_lock();

	up = get_up(muxl, id);

	spin_unlock(&muxl->receive_lock);



	if (up == NULL) {

		pr_info("Received data on unknown link ID = %d (0x%x) up == NULL",

			id, id);

		pr_debug("Received data on unknown link ID = %d (0x%x)"

			" up == NULL", id, id);

		cfpkt_destroy(pkt);

		/*

		 * Don't return ERROR, since modem misbehaves and sends out

		 * flow on before linksetup response.

		 */



		rcu_read_unlock();

		return /* CFGLU_EPROT; */ 0;

	}



	/* We can't hold rcu_lock during receive, so take a ref count instead */

	cfsrvl_get(up);

	rcu_read_unlock();



	ret = up->receive(up, pkt);



	cfsrvl_put(up);

	return ret;

}
@@ -185,31 +198,49 @@ static int cfmuxl_receive(struct cflayer *layr, struct cfpkt *pkt) 
static int cfmuxl_transmit(struct cflayer *layr, struct cfpkt *pkt)

{

	struct cfmuxl *muxl = container_obj(layr);

	int err;

	u8 linkid;

	struct cflayer *dn;

	struct caif_payload_info *info = cfpkt_info(pkt);

	BUG_ON(!info);



	rcu_read_lock();



	dn = get_dn(muxl, info->dev_info);

	if (dn == NULL) {

		pr_warn("Send data on unknown phy ID = %d (0x%x)\n",

		pr_debug("Send data on unknown phy ID = %d (0x%x)\n",

			info->dev_info->id, info->dev_info->id);

		rcu_read_unlock();

		cfpkt_destroy(pkt);

		return -ENOTCONN;

	}



	info->hdr_len += 1;

	linkid = info->channel_id;

	cfpkt_add_head(pkt, &linkid, 1);

	return dn->transmit(dn, pkt);



	/* We can't hold rcu_lock during receive, so take a ref count instead */

	cffrml_hold(dn);



	rcu_read_unlock();



	err = dn->transmit(dn, pkt);



	cffrml_put(dn);

	return err;

}



static void cfmuxl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,

				int phyid)

{

	struct cfmuxl *muxl = container_obj(layr);

	struct list_head *node, *next;

	struct cflayer *layer;

	list_for_each_safe(node, next, &muxl->srvl_list) {

		layer = list_entry(node, struct cflayer, node);

		if (cfsrvl_phyid_match(layer, phyid))



	rcu_read_lock();

	list_for_each_entry_rcu(layer, &muxl->srvl_list, node) {

		if (cfsrvl_phyid_match(layer, phyid) && layer->ctrlcmd)

			/* NOTE: ctrlcmd is not allowed to block */

			layer->ctrlcmd(layer, ctrl, phyid);

	}

	rcu_read_unlock();

}

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