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Linux/net/caif/cfrfml.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 <asm/unaligned.h>
 13 #include <net/caif/caif_layer.h>
 14 #include <net/caif/cfsrvl.h>
 15 #include <net/caif/cfpkt.h>
 16 
 17 #define container_obj(layr) container_of(layr, struct cfrfml, serv.layer)
 18 #define RFM_SEGMENTATION_BIT 0x01
 19 #define RFM_HEAD_SIZE 7
 20 
 21 static int cfrfml_receive(struct cflayer *layr, struct cfpkt *pkt);
 22 static int cfrfml_transmit(struct cflayer *layr, struct cfpkt *pkt);
 23 
 24 struct cfrfml {
 25         struct cfsrvl serv;
 26         struct cfpkt *incomplete_frm;
 27         int fragment_size;
 28         u8  seghead[6];
 29         u16 pdu_size;
 30         /* Protects serialized processing of packets */
 31         spinlock_t sync;
 32 };
 33 
 34 static void cfrfml_release(struct cflayer *layer)
 35 {
 36         struct cfsrvl *srvl = container_of(layer, struct cfsrvl, layer);
 37         struct cfrfml *rfml = container_obj(&srvl->layer);
 38 
 39         if (rfml->incomplete_frm)
 40                 cfpkt_destroy(rfml->incomplete_frm);
 41 
 42         kfree(srvl);
 43 }
 44 
 45 struct cflayer *cfrfml_create(u8 channel_id, struct dev_info *dev_info,
 46                               int mtu_size)
 47 {
 48         int tmp;
 49         struct cfrfml *this = kzalloc(sizeof(struct cfrfml), GFP_ATOMIC);
 50 
 51         if (!this)
 52                 return NULL;
 53 
 54         cfsrvl_init(&this->serv, channel_id, dev_info, false);
 55         this->serv.release = cfrfml_release;
 56         this->serv.layer.receive = cfrfml_receive;
 57         this->serv.layer.transmit = cfrfml_transmit;
 58 
 59         /* Round down to closest multiple of 16 */
 60         tmp = (mtu_size - RFM_HEAD_SIZE - 6) / 16;
 61         tmp *= 16;
 62 
 63         this->fragment_size = tmp;
 64         spin_lock_init(&this->sync);
 65         snprintf(this->serv.layer.name, CAIF_LAYER_NAME_SZ,
 66                 "rfm%d", channel_id);
 67 
 68         return &this->serv.layer;
 69 }
 70 
 71 static struct cfpkt *rfm_append(struct cfrfml *rfml, char *seghead,
 72                                 struct cfpkt *pkt, int *err)
 73 {
 74         struct cfpkt *tmppkt;
 75         *err = -EPROTO;
 76         /* n-th but not last segment */
 77 
 78         if (cfpkt_extr_head(pkt, seghead, 6) < 0)
 79                 return NULL;
 80 
 81         /* Verify correct header */
 82         if (memcmp(seghead, rfml->seghead, 6) != 0)
 83                 return NULL;
 84 
 85         tmppkt = cfpkt_append(rfml->incomplete_frm, pkt,
 86                         rfml->pdu_size + RFM_HEAD_SIZE);
 87 
 88         /* If cfpkt_append failes input pkts are not freed */
 89         *err = -ENOMEM;
 90         if (tmppkt == NULL)
 91                 return NULL;
 92 
 93         *err = 0;
 94         return tmppkt;
 95 }
 96 
 97 static int cfrfml_receive(struct cflayer *layr, struct cfpkt *pkt)
 98 {
 99         u8 tmp;
100         bool segmented;
101         int err;
102         u8 seghead[6];
103         struct cfrfml *rfml;
104         struct cfpkt *tmppkt = NULL;
105 
106         caif_assert(layr->up != NULL);
107         caif_assert(layr->receive != NULL);
108         rfml = container_obj(layr);
109         spin_lock(&rfml->sync);
110 
111         err = -EPROTO;
112         if (cfpkt_extr_head(pkt, &tmp, 1) < 0)
113                 goto out;
114         segmented = tmp & RFM_SEGMENTATION_BIT;
115 
116         if (segmented) {
117                 if (rfml->incomplete_frm == NULL) {
118                         /* Initial Segment */
119                         if (cfpkt_peek_head(pkt, rfml->seghead, 6) < 0)
120                                 goto out;
121 
122                         rfml->pdu_size = get_unaligned_le16(rfml->seghead+4);
123 
124                         if (cfpkt_erroneous(pkt))
125                                 goto out;
126                         rfml->incomplete_frm = pkt;
127                         pkt = NULL;
128                 } else {
129 
130                         tmppkt = rfm_append(rfml, seghead, pkt, &err);
131                         if (tmppkt == NULL)
132                                 goto out;
133 
134                         if (cfpkt_erroneous(tmppkt))
135                                 goto out;
136 
137                         rfml->incomplete_frm = tmppkt;
138 
139 
140                         if (cfpkt_erroneous(tmppkt))
141                                 goto out;
142                 }
143                 err = 0;
144                 goto out;
145         }
146 
147         if (rfml->incomplete_frm) {
148 
149                 /* Last Segment */
150                 tmppkt = rfm_append(rfml, seghead, pkt, &err);
151                 if (tmppkt == NULL)
152                         goto out;
153 
154                 if (cfpkt_erroneous(tmppkt))
155                         goto out;
156 
157                 rfml->incomplete_frm = NULL;
158                 pkt = tmppkt;
159                 tmppkt = NULL;
160 
161                 /* Verify that length is correct */
162                 err = EPROTO;
163                 if (rfml->pdu_size != cfpkt_getlen(pkt) - RFM_HEAD_SIZE + 1)
164                         goto out;
165         }
166 
167         err = rfml->serv.layer.up->receive(rfml->serv.layer.up, pkt);
168 
169 out:
170 
171         if (err != 0) {
172                 if (tmppkt)
173                         cfpkt_destroy(tmppkt);
174                 if (pkt)
175                         cfpkt_destroy(pkt);
176                 if (rfml->incomplete_frm)
177                         cfpkt_destroy(rfml->incomplete_frm);
178                 rfml->incomplete_frm = NULL;
179 
180                 pr_info("Connection error %d triggered on RFM link\n", err);
181 
182                 /* Trigger connection error upon failure.*/
183                 layr->up->ctrlcmd(layr->up, CAIF_CTRLCMD_REMOTE_SHUTDOWN_IND,
184                                         rfml->serv.dev_info.id);
185         }
186         spin_unlock(&rfml->sync);
187 
188         if (unlikely(err == -EAGAIN))
189                 /* It is not possible to recover after drop of a fragment */
190                 err = -EIO;
191 
192         return err;
193 }
194 
195 
196 static int cfrfml_transmit_segment(struct cfrfml *rfml, struct cfpkt *pkt)
197 {
198         caif_assert(cfpkt_getlen(pkt) < rfml->fragment_size + RFM_HEAD_SIZE);
199 
200         /* Add info for MUX-layer to route the packet out. */
201         cfpkt_info(pkt)->channel_id = rfml->serv.layer.id;
202 
203         /*
204          * To optimize alignment, we add up the size of CAIF header before
205          * payload.
206          */
207         cfpkt_info(pkt)->hdr_len = RFM_HEAD_SIZE;
208         cfpkt_info(pkt)->dev_info = &rfml->serv.dev_info;
209 
210         return rfml->serv.layer.dn->transmit(rfml->serv.layer.dn, pkt);
211 }
212 
213 static int cfrfml_transmit(struct cflayer *layr, struct cfpkt *pkt)
214 {
215         int err;
216         u8 seg;
217         u8 head[6];
218         struct cfpkt *rearpkt = NULL;
219         struct cfpkt *frontpkt = pkt;
220         struct cfrfml *rfml = container_obj(layr);
221 
222         caif_assert(layr->dn != NULL);
223         caif_assert(layr->dn->transmit != NULL);
224 
225         if (!cfsrvl_ready(&rfml->serv, &err))
226                 goto out;
227 
228         err = -EPROTO;
229         if (cfpkt_getlen(pkt) <= RFM_HEAD_SIZE-1)
230                 goto out;
231 
232         err = 0;
233         if (cfpkt_getlen(pkt) > rfml->fragment_size + RFM_HEAD_SIZE)
234                 err = cfpkt_peek_head(pkt, head, 6);
235 
236         if (err < 0)
237                 goto out;
238 
239         while (cfpkt_getlen(frontpkt) > rfml->fragment_size + RFM_HEAD_SIZE) {
240 
241                 seg = 1;
242                 err = -EPROTO;
243 
244                 if (cfpkt_add_head(frontpkt, &seg, 1) < 0)
245                         goto out;
246                 /*
247                  * On OOM error cfpkt_split returns NULL.
248                  *
249                  * NOTE: Segmented pdu is not correctly aligned.
250                  * This has negative performance impact.
251                  */
252 
253                 rearpkt = cfpkt_split(frontpkt, rfml->fragment_size);
254                 if (rearpkt == NULL)
255                         goto out;
256 
257                 err = cfrfml_transmit_segment(rfml, frontpkt);
258 
259                 if (err != 0) {
260                         frontpkt = NULL;
261                         goto out;
262                 }
263 
264                 frontpkt = rearpkt;
265                 rearpkt = NULL;
266 
267                 err = -ENOMEM;
268                 if (frontpkt == NULL)
269                         goto out;
270                 err = -EPROTO;
271                 if (cfpkt_add_head(frontpkt, head, 6) < 0)
272                         goto out;
273 
274         }
275 
276         seg = 0;
277         err = -EPROTO;
278 
279         if (cfpkt_add_head(frontpkt, &seg, 1) < 0)
280                 goto out;
281 
282         err = cfrfml_transmit_segment(rfml, frontpkt);
283 
284         frontpkt = NULL;
285 out:
286 
287         if (err != 0) {
288                 pr_info("Connection error %d triggered on RFM link\n", err);
289                 /* Trigger connection error upon failure.*/
290 
291                 layr->up->ctrlcmd(layr->up, CAIF_CTRLCMD_REMOTE_SHUTDOWN_IND,
292                                         rfml->serv.dev_info.id);
293 
294                 if (rearpkt)
295                         cfpkt_destroy(rearpkt);
296 
297                 if (frontpkt)
298                         cfpkt_destroy(frontpkt);
299         }
300 
301         return err;
302 }
303 

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