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TOMOYO Linux Cross Reference
Linux/net/caif/cfmuxl.c

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  1 /*
  2  * Copyright (C) ST-Ericsson AB 2010
  3  * Author:      Sjur Brendeland
  4  * License terms: GNU General Public License (GPL) version 2
  5  */
  6 
  7 #define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
  8 
  9 #include <linux/stddef.h>
 10 #include <linux/spinlock.h>
 11 #include <linux/slab.h>
 12 #include <linux/rculist.h>
 13 #include <net/caif/cfpkt.h>
 14 #include <net/caif/cfmuxl.h>
 15 #include <net/caif/cfsrvl.h>
 16 #include <net/caif/cffrml.h>
 17 
 18 #define container_obj(layr) container_of(layr, struct cfmuxl, layer)
 19 
 20 #define CAIF_CTRL_CHANNEL 0
 21 #define UP_CACHE_SIZE 8
 22 #define DN_CACHE_SIZE 8
 23 
 24 struct cfmuxl {
 25         struct cflayer layer;
 26         struct list_head srvl_list;
 27         struct list_head frml_list;
 28         struct cflayer *up_cache[UP_CACHE_SIZE];
 29         struct cflayer *dn_cache[DN_CACHE_SIZE];
 30         /*
 31          * Set when inserting or removing downwards layers.
 32          */
 33         spinlock_t transmit_lock;
 34 
 35         /*
 36          * Set when inserting or removing upwards layers.
 37          */
 38         spinlock_t receive_lock;
 39 
 40 };
 41 
 42 static int cfmuxl_receive(struct cflayer *layr, struct cfpkt *pkt);
 43 static int cfmuxl_transmit(struct cflayer *layr, struct cfpkt *pkt);
 44 static void cfmuxl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
 45                            int phyid);
 46 static struct cflayer *get_up(struct cfmuxl *muxl, u16 id);
 47 
 48 struct cflayer *cfmuxl_create(void)
 49 {
 50         struct cfmuxl *this = kzalloc(sizeof(struct cfmuxl), GFP_ATOMIC);
 51 
 52         if (!this)
 53                 return NULL;
 54         this->layer.receive = cfmuxl_receive;
 55         this->layer.transmit = cfmuxl_transmit;
 56         this->layer.ctrlcmd = cfmuxl_ctrlcmd;
 57         INIT_LIST_HEAD(&this->srvl_list);
 58         INIT_LIST_HEAD(&this->frml_list);
 59         spin_lock_init(&this->transmit_lock);
 60         spin_lock_init(&this->receive_lock);
 61         snprintf(this->layer.name, CAIF_LAYER_NAME_SZ, "mux");
 62         return &this->layer;
 63 }
 64 
 65 int cfmuxl_set_dnlayer(struct cflayer *layr, struct cflayer *dn, u8 phyid)
 66 {
 67         struct cfmuxl *muxl = (struct cfmuxl *) layr;
 68 
 69         spin_lock_bh(&muxl->transmit_lock);
 70         list_add_rcu(&dn->node, &muxl->frml_list);
 71         spin_unlock_bh(&muxl->transmit_lock);
 72         return 0;
 73 }
 74 
 75 static struct cflayer *get_from_id(struct list_head *list, u16 id)
 76 {
 77         struct cflayer *lyr;
 78         list_for_each_entry_rcu(lyr, list, node) {
 79                 if (lyr->id == id)
 80                         return lyr;
 81         }
 82 
 83         return NULL;
 84 }
 85 
 86 int cfmuxl_set_uplayer(struct cflayer *layr, struct cflayer *up, u8 linkid)
 87 {
 88         struct cfmuxl *muxl = container_obj(layr);
 89         struct cflayer *old;
 90 
 91         spin_lock_bh(&muxl->receive_lock);
 92 
 93         /* Two entries with same id is wrong, so remove old layer from mux */
 94         old = get_from_id(&muxl->srvl_list, linkid);
 95         if (old != NULL)
 96                 list_del_rcu(&old->node);
 97 
 98         list_add_rcu(&up->node, &muxl->srvl_list);
 99         spin_unlock_bh(&muxl->receive_lock);
100 
101         return 0;
102 }
103 
104 struct cflayer *cfmuxl_remove_dnlayer(struct cflayer *layr, u8 phyid)
105 {
106         struct cfmuxl *muxl = container_obj(layr);
107         struct cflayer *dn;
108         int idx = phyid % DN_CACHE_SIZE;
109 
110         spin_lock_bh(&muxl->transmit_lock);
111         RCU_INIT_POINTER(muxl->dn_cache[idx], NULL);
112         dn = get_from_id(&muxl->frml_list, phyid);
113         if (dn == NULL)
114                 goto out;
115 
116         list_del_rcu(&dn->node);
117         caif_assert(dn != NULL);
118 out:
119         spin_unlock_bh(&muxl->transmit_lock);
120         return dn;
121 }
122 
123 static struct cflayer *get_up(struct cfmuxl *muxl, u16 id)
124 {
125         struct cflayer *up;
126         int idx = id % UP_CACHE_SIZE;
127         up = rcu_dereference(muxl->up_cache[idx]);
128         if (up == NULL || up->id != id) {
129                 spin_lock_bh(&muxl->receive_lock);
130                 up = get_from_id(&muxl->srvl_list, id);
131                 rcu_assign_pointer(muxl->up_cache[idx], up);
132                 spin_unlock_bh(&muxl->receive_lock);
133         }
134         return up;
135 }
136 
137 static struct cflayer *get_dn(struct cfmuxl *muxl, struct dev_info *dev_info)
138 {
139         struct cflayer *dn;
140         int idx = dev_info->id % DN_CACHE_SIZE;
141         dn = rcu_dereference(muxl->dn_cache[idx]);
142         if (dn == NULL || dn->id != dev_info->id) {
143                 spin_lock_bh(&muxl->transmit_lock);
144                 dn = get_from_id(&muxl->frml_list, dev_info->id);
145                 rcu_assign_pointer(muxl->dn_cache[idx], dn);
146                 spin_unlock_bh(&muxl->transmit_lock);
147         }
148         return dn;
149 }
150 
151 struct cflayer *cfmuxl_remove_uplayer(struct cflayer *layr, u8 id)
152 {
153         struct cflayer *up;
154         struct cfmuxl *muxl = container_obj(layr);
155         int idx = id % UP_CACHE_SIZE;
156 
157         if (id == 0) {
158                 pr_warn("Trying to remove control layer\n");
159                 return NULL;
160         }
161 
162         spin_lock_bh(&muxl->receive_lock);
163         up = get_from_id(&muxl->srvl_list, id);
164         if (up == NULL)
165                 goto out;
166 
167         RCU_INIT_POINTER(muxl->up_cache[idx], NULL);
168         list_del_rcu(&up->node);
169 out:
170         spin_unlock_bh(&muxl->receive_lock);
171         return up;
172 }
173 
174 static int cfmuxl_receive(struct cflayer *layr, struct cfpkt *pkt)
175 {
176         int ret;
177         struct cfmuxl *muxl = container_obj(layr);
178         u8 id;
179         struct cflayer *up;
180         if (cfpkt_extr_head(pkt, &id, 1) < 0) {
181                 pr_err("erroneous Caif Packet\n");
182                 cfpkt_destroy(pkt);
183                 return -EPROTO;
184         }
185         rcu_read_lock();
186         up = get_up(muxl, id);
187 
188         if (up == NULL) {
189                 pr_debug("Received data on unknown link ID = %d (0x%x)"
190                         " up == NULL", id, id);
191                 cfpkt_destroy(pkt);
192                 /*
193                  * Don't return ERROR, since modem misbehaves and sends out
194                  * flow on before linksetup response.
195                  */
196 
197                 rcu_read_unlock();
198                 return /* CFGLU_EPROT; */ 0;
199         }
200 
201         /* We can't hold rcu_lock during receive, so take a ref count instead */
202         cfsrvl_get(up);
203         rcu_read_unlock();
204 
205         ret = up->receive(up, pkt);
206 
207         cfsrvl_put(up);
208         return ret;
209 }
210 
211 static int cfmuxl_transmit(struct cflayer *layr, struct cfpkt *pkt)
212 {
213         struct cfmuxl *muxl = container_obj(layr);
214         int err;
215         u8 linkid;
216         struct cflayer *dn;
217         struct caif_payload_info *info = cfpkt_info(pkt);
218         BUG_ON(!info);
219 
220         rcu_read_lock();
221 
222         dn = get_dn(muxl, info->dev_info);
223         if (dn == NULL) {
224                 pr_debug("Send data on unknown phy ID = %d (0x%x)\n",
225                         info->dev_info->id, info->dev_info->id);
226                 rcu_read_unlock();
227                 cfpkt_destroy(pkt);
228                 return -ENOTCONN;
229         }
230 
231         info->hdr_len += 1;
232         linkid = info->channel_id;
233         cfpkt_add_head(pkt, &linkid, 1);
234 
235         /* We can't hold rcu_lock during receive, so take a ref count instead */
236         cffrml_hold(dn);
237 
238         rcu_read_unlock();
239 
240         err = dn->transmit(dn, pkt);
241 
242         cffrml_put(dn);
243         return err;
244 }
245 
246 static void cfmuxl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
247                            int phyid)
248 {
249         struct cfmuxl *muxl = container_obj(layr);
250         struct cflayer *layer;
251 
252         rcu_read_lock();
253         list_for_each_entry_rcu(layer, &muxl->srvl_list, node) {
254 
255                 if (cfsrvl_phyid_match(layer, phyid) && layer->ctrlcmd) {
256 
257                         if ((ctrl == _CAIF_CTRLCMD_PHYIF_DOWN_IND ||
258                                 ctrl == CAIF_CTRLCMD_REMOTE_SHUTDOWN_IND) &&
259                                         layer->id != 0)
260                                 cfmuxl_remove_uplayer(layr, layer->id);
261 
262                         /* NOTE: ctrlcmd is not allowed to block */
263                         layer->ctrlcmd(layer, ctrl, phyid);
264                 }
265         }
266         rcu_read_unlock();
267 }
268 

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