linux/net/caif/cfrfml.c
Colin Ian King 5d288b8865 net: caif: remove redundant null check on frontpkt
It is impossible for frontpkt to be null at the point of the null
check because it has been assigned from rearpkt and there is no
way rearpkt can be null at the point of the assignment because
of the sanity checking and exit paths taken previously. Remove
the redundant null check.

Detected by CoverityScan, CID#114434 ("Logically dead code")

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-09-17 18:49:57 -07:00

300 lines
6.3 KiB
C

/*
* Copyright (C) ST-Ericsson AB 2010
* Author: Sjur Brendeland
* License terms: GNU General Public License (GPL) version 2
*/
#define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
#include <linux/stddef.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <asm/unaligned.h>
#include <net/caif/caif_layer.h>
#include <net/caif/cfsrvl.h>
#include <net/caif/cfpkt.h>
#define container_obj(layr) container_of(layr, struct cfrfml, serv.layer)
#define RFM_SEGMENTATION_BIT 0x01
#define RFM_HEAD_SIZE 7
static int cfrfml_receive(struct cflayer *layr, struct cfpkt *pkt);
static int cfrfml_transmit(struct cflayer *layr, struct cfpkt *pkt);
struct cfrfml {
struct cfsrvl serv;
struct cfpkt *incomplete_frm;
int fragment_size;
u8 seghead[6];
u16 pdu_size;
/* Protects serialized processing of packets */
spinlock_t sync;
};
static void cfrfml_release(struct cflayer *layer)
{
struct cfsrvl *srvl = container_of(layer, struct cfsrvl, layer);
struct cfrfml *rfml = container_obj(&srvl->layer);
if (rfml->incomplete_frm)
cfpkt_destroy(rfml->incomplete_frm);
kfree(srvl);
}
struct cflayer *cfrfml_create(u8 channel_id, struct dev_info *dev_info,
int mtu_size)
{
int tmp;
struct cfrfml *this = kzalloc(sizeof(struct cfrfml), GFP_ATOMIC);
if (!this)
return NULL;
cfsrvl_init(&this->serv, channel_id, dev_info, false);
this->serv.release = cfrfml_release;
this->serv.layer.receive = cfrfml_receive;
this->serv.layer.transmit = cfrfml_transmit;
/* Round down to closest multiple of 16 */
tmp = (mtu_size - RFM_HEAD_SIZE - 6) / 16;
tmp *= 16;
this->fragment_size = tmp;
spin_lock_init(&this->sync);
snprintf(this->serv.layer.name, CAIF_LAYER_NAME_SZ,
"rfm%d", channel_id);
return &this->serv.layer;
}
static struct cfpkt *rfm_append(struct cfrfml *rfml, char *seghead,
struct cfpkt *pkt, int *err)
{
struct cfpkt *tmppkt;
*err = -EPROTO;
/* n-th but not last segment */
if (cfpkt_extr_head(pkt, seghead, 6) < 0)
return NULL;
/* Verify correct header */
if (memcmp(seghead, rfml->seghead, 6) != 0)
return NULL;
tmppkt = cfpkt_append(rfml->incomplete_frm, pkt,
rfml->pdu_size + RFM_HEAD_SIZE);
/* If cfpkt_append failes input pkts are not freed */
*err = -ENOMEM;
if (tmppkt == NULL)
return NULL;
*err = 0;
return tmppkt;
}
static int cfrfml_receive(struct cflayer *layr, struct cfpkt *pkt)
{
u8 tmp;
bool segmented;
int err;
u8 seghead[6];
struct cfrfml *rfml;
struct cfpkt *tmppkt = NULL;
caif_assert(layr->up != NULL);
caif_assert(layr->receive != NULL);
rfml = container_obj(layr);
spin_lock(&rfml->sync);
err = -EPROTO;
if (cfpkt_extr_head(pkt, &tmp, 1) < 0)
goto out;
segmented = tmp & RFM_SEGMENTATION_BIT;
if (segmented) {
if (rfml->incomplete_frm == NULL) {
/* Initial Segment */
if (cfpkt_peek_head(pkt, rfml->seghead, 6) < 0)
goto out;
rfml->pdu_size = get_unaligned_le16(rfml->seghead+4);
if (cfpkt_erroneous(pkt))
goto out;
rfml->incomplete_frm = pkt;
pkt = NULL;
} else {
tmppkt = rfm_append(rfml, seghead, pkt, &err);
if (tmppkt == NULL)
goto out;
if (cfpkt_erroneous(tmppkt))
goto out;
rfml->incomplete_frm = tmppkt;
if (cfpkt_erroneous(tmppkt))
goto out;
}
err = 0;
goto out;
}
if (rfml->incomplete_frm) {
/* Last Segment */
tmppkt = rfm_append(rfml, seghead, pkt, &err);
if (tmppkt == NULL)
goto out;
if (cfpkt_erroneous(tmppkt))
goto out;
rfml->incomplete_frm = NULL;
pkt = tmppkt;
tmppkt = NULL;
/* Verify that length is correct */
err = -EPROTO;
if (rfml->pdu_size != cfpkt_getlen(pkt) - RFM_HEAD_SIZE + 1)
goto out;
}
err = rfml->serv.layer.up->receive(rfml->serv.layer.up, pkt);
out:
if (err != 0) {
if (tmppkt)
cfpkt_destroy(tmppkt);
if (pkt)
cfpkt_destroy(pkt);
if (rfml->incomplete_frm)
cfpkt_destroy(rfml->incomplete_frm);
rfml->incomplete_frm = NULL;
pr_info("Connection error %d triggered on RFM link\n", err);
/* Trigger connection error upon failure.*/
layr->up->ctrlcmd(layr->up, CAIF_CTRLCMD_REMOTE_SHUTDOWN_IND,
rfml->serv.dev_info.id);
}
spin_unlock(&rfml->sync);
if (unlikely(err == -EAGAIN))
/* It is not possible to recover after drop of a fragment */
err = -EIO;
return err;
}
static int cfrfml_transmit_segment(struct cfrfml *rfml, struct cfpkt *pkt)
{
caif_assert(cfpkt_getlen(pkt) < rfml->fragment_size + RFM_HEAD_SIZE);
/* Add info for MUX-layer to route the packet out. */
cfpkt_info(pkt)->channel_id = rfml->serv.layer.id;
/*
* To optimize alignment, we add up the size of CAIF header before
* payload.
*/
cfpkt_info(pkt)->hdr_len = RFM_HEAD_SIZE;
cfpkt_info(pkt)->dev_info = &rfml->serv.dev_info;
return rfml->serv.layer.dn->transmit(rfml->serv.layer.dn, pkt);
}
static int cfrfml_transmit(struct cflayer *layr, struct cfpkt *pkt)
{
int err;
u8 seg;
u8 head[6];
struct cfpkt *rearpkt = NULL;
struct cfpkt *frontpkt = pkt;
struct cfrfml *rfml = container_obj(layr);
caif_assert(layr->dn != NULL);
caif_assert(layr->dn->transmit != NULL);
if (!cfsrvl_ready(&rfml->serv, &err))
goto out;
err = -EPROTO;
if (cfpkt_getlen(pkt) <= RFM_HEAD_SIZE-1)
goto out;
err = 0;
if (cfpkt_getlen(pkt) > rfml->fragment_size + RFM_HEAD_SIZE)
err = cfpkt_peek_head(pkt, head, 6);
if (err < 0)
goto out;
while (cfpkt_getlen(frontpkt) > rfml->fragment_size + RFM_HEAD_SIZE) {
seg = 1;
err = -EPROTO;
if (cfpkt_add_head(frontpkt, &seg, 1) < 0)
goto out;
/*
* On OOM error cfpkt_split returns NULL.
*
* NOTE: Segmented pdu is not correctly aligned.
* This has negative performance impact.
*/
rearpkt = cfpkt_split(frontpkt, rfml->fragment_size);
if (rearpkt == NULL)
goto out;
err = cfrfml_transmit_segment(rfml, frontpkt);
if (err != 0) {
frontpkt = NULL;
goto out;
}
frontpkt = rearpkt;
rearpkt = NULL;
err = -EPROTO;
if (cfpkt_add_head(frontpkt, head, 6) < 0)
goto out;
}
seg = 0;
err = -EPROTO;
if (cfpkt_add_head(frontpkt, &seg, 1) < 0)
goto out;
err = cfrfml_transmit_segment(rfml, frontpkt);
frontpkt = NULL;
out:
if (err != 0) {
pr_info("Connection error %d triggered on RFM link\n", err);
/* Trigger connection error upon failure.*/
layr->up->ctrlcmd(layr->up, CAIF_CTRLCMD_REMOTE_SHUTDOWN_IND,
rfml->serv.dev_info.id);
if (rearpkt)
cfpkt_destroy(rearpkt);
if (frontpkt)
cfpkt_destroy(frontpkt);
}
return err;
}