Commit 87397fe1 authored by Andre Naujoks's avatar Andre Naujoks Committed by David S. Miller

slcan: rewrite of slc_bump and slc_encaps

The old implementation was heavy on str* functions and sprintf calls.
This version is more manual, but faster.

Profiling just the printing of a 3 char CAN-id resulted in 60 instructions
for the manual method and over 2000 for the sprintf method. Bear in
mind the profiling was done against libc and not the kernel sprintf.

Together with this rewrite an issue with sending and receiving of RTR frames
has been fixed by Oliver for the cases that the DLC is not zero.
Signed-off-by: default avatarAndre Naujoks <nautsch2@gmail.com>
Tested-by: default avatarOliver Hartkopp <socketcan@hartkopp.net>
Acked-by: default avatarOliver Hartkopp <socketcan@hartkopp.net>
Acked-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c26d436c
...@@ -76,6 +76,10 @@ MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces"); ...@@ -76,6 +76,10 @@ MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces");
/* maximum rx buffer len: extended CAN frame with timestamp */ /* maximum rx buffer len: extended CAN frame with timestamp */
#define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1) #define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1)
#define SLC_CMD_LEN 1
#define SLC_SFF_ID_LEN 3
#define SLC_EFF_ID_LEN 8
struct slcan { struct slcan {
int magic; int magic;
...@@ -142,48 +146,64 @@ static void slc_bump(struct slcan *sl) ...@@ -142,48 +146,64 @@ static void slc_bump(struct slcan *sl)
{ {
struct sk_buff *skb; struct sk_buff *skb;
struct can_frame cf; struct can_frame cf;
int i, dlc_pos, tmp; int i, tmp;
unsigned long ultmp; u32 tmpid;
char cmd = sl->rbuff[0]; char *cmd = sl->rbuff;
if ((cmd != 't') && (cmd != 'T') && (cmd != 'r') && (cmd != 'R')) cf.can_id = 0;
switch (*cmd) {
case 'r':
cf.can_id = CAN_RTR_FLAG;
/* fallthrough */
case 't':
/* store dlc ASCII value and terminate SFF CAN ID string */
cf.can_dlc = sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN];
sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN] = 0;
/* point to payload data behind the dlc */
cmd += SLC_CMD_LEN + SLC_SFF_ID_LEN + 1;
break;
case 'R':
cf.can_id = CAN_RTR_FLAG;
/* fallthrough */
case 'T':
cf.can_id |= CAN_EFF_FLAG;
/* store dlc ASCII value and terminate EFF CAN ID string */
cf.can_dlc = sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN];
sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN] = 0;
/* point to payload data behind the dlc */
cmd += SLC_CMD_LEN + SLC_EFF_ID_LEN + 1;
break;
default:
return; return;
}
if (cmd & 0x20) /* tiny chars 'r' 't' => standard frame format */ if (kstrtou32(sl->rbuff + SLC_CMD_LEN, 16, &tmpid))
dlc_pos = 4; /* dlc position tiiid */
else
dlc_pos = 9; /* dlc position Tiiiiiiiid */
if (!((sl->rbuff[dlc_pos] >= '0') && (sl->rbuff[dlc_pos] < '9')))
return; return;
cf.can_dlc = sl->rbuff[dlc_pos] - '0'; /* get can_dlc from ASCII val */ cf.can_id |= tmpid;
sl->rbuff[dlc_pos] = 0; /* terminate can_id string */
if (kstrtoul(sl->rbuff+1, 16, &ultmp)) /* get can_dlc from sanitized ASCII value */
if (cf.can_dlc >= '0' && cf.can_dlc < '9')
cf.can_dlc -= '0';
else
return; return;
cf.can_id = ultmp;
if (!(cmd & 0x20)) /* NO tiny chars => extended frame format */
cf.can_id |= CAN_EFF_FLAG;
if ((cmd | 0x20) == 'r') /* RTR frame */
cf.can_id |= CAN_RTR_FLAG;
*(u64 *) (&cf.data) = 0; /* clear payload */ *(u64 *) (&cf.data) = 0; /* clear payload */
for (i = 0, dlc_pos++; i < cf.can_dlc; i++) { /* RTR frames may have a dlc > 0 but they never have any data bytes */
tmp = hex_to_bin(sl->rbuff[dlc_pos++]); if (!(cf.can_id & CAN_RTR_FLAG)) {
for (i = 0; i < cf.can_dlc; i++) {
tmp = hex_to_bin(*cmd++);
if (tmp < 0) if (tmp < 0)
return; return;
cf.data[i] = (tmp << 4); cf.data[i] = (tmp << 4);
tmp = hex_to_bin(sl->rbuff[dlc_pos++]); tmp = hex_to_bin(*cmd++);
if (tmp < 0) if (tmp < 0)
return; return;
cf.data[i] |= tmp; cf.data[i] |= tmp;
} }
}
skb = dev_alloc_skb(sizeof(struct can_frame) + skb = dev_alloc_skb(sizeof(struct can_frame) +
sizeof(struct can_skb_priv)); sizeof(struct can_skb_priv));
...@@ -209,7 +229,6 @@ static void slc_bump(struct slcan *sl) ...@@ -209,7 +229,6 @@ static void slc_bump(struct slcan *sl)
/* parse tty input stream */ /* parse tty input stream */
static void slcan_unesc(struct slcan *sl, unsigned char s) static void slcan_unesc(struct slcan *sl, unsigned char s)
{ {
if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */ if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */
if (!test_and_clear_bit(SLF_ERROR, &sl->flags) && if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
(sl->rcount > 4)) { (sl->rcount > 4)) {
...@@ -236,27 +255,46 @@ static void slcan_unesc(struct slcan *sl, unsigned char s) ...@@ -236,27 +255,46 @@ static void slcan_unesc(struct slcan *sl, unsigned char s)
/* Encapsulate one can_frame and stuff into a TTY queue. */ /* Encapsulate one can_frame and stuff into a TTY queue. */
static void slc_encaps(struct slcan *sl, struct can_frame *cf) static void slc_encaps(struct slcan *sl, struct can_frame *cf)
{ {
int actual, idx, i; int actual, i;
char cmd; unsigned char *pos;
unsigned char *endpos;
canid_t id = cf->can_id;
pos = sl->xbuff;
if (cf->can_id & CAN_RTR_FLAG) if (cf->can_id & CAN_RTR_FLAG)
cmd = 'R'; /* becomes 'r' in standard frame format */ *pos = 'R'; /* becomes 'r' in standard frame format (SFF) */
else else
cmd = 'T'; /* becomes 't' in standard frame format */ *pos = 'T'; /* becomes 't' in standard frame format (SSF) */
if (cf->can_id & CAN_EFF_FLAG) /* determine number of chars for the CAN-identifier */
sprintf(sl->xbuff, "%c%08X%d", cmd, if (cf->can_id & CAN_EFF_FLAG) {
cf->can_id & CAN_EFF_MASK, cf->can_dlc); id &= CAN_EFF_MASK;
else endpos = pos + SLC_EFF_ID_LEN;
sprintf(sl->xbuff, "%c%03X%d", cmd | 0x20, } else {
cf->can_id & CAN_SFF_MASK, cf->can_dlc); *pos |= 0x20; /* convert R/T to lower case for SFF */
id &= CAN_SFF_MASK;
endpos = pos + SLC_SFF_ID_LEN;
}
/* build 3 (SFF) or 8 (EFF) digit CAN identifier */
pos++;
while (endpos >= pos) {
*endpos-- = hex_asc_upper[id & 0xf];
id >>= 4;
}
pos += (cf->can_id & CAN_EFF_FLAG) ? SLC_EFF_ID_LEN : SLC_SFF_ID_LEN;
idx = strlen(sl->xbuff); *pos++ = cf->can_dlc + '0';
/* RTR frames may have a dlc > 0 but they never have any data bytes */
if (!(cf->can_id & CAN_RTR_FLAG)) {
for (i = 0; i < cf->can_dlc; i++) for (i = 0; i < cf->can_dlc; i++)
sprintf(&sl->xbuff[idx + 2*i], "%02X", cf->data[i]); pos = hex_byte_pack_upper(pos, cf->data[i]);
}
strcat(sl->xbuff, "\r"); /* add terminating character */ *pos++ = '\r';
/* Order of next two lines is *very* important. /* Order of next two lines is *very* important.
* When we are sending a little amount of data, * When we are sending a little amount of data,
...@@ -267,8 +305,8 @@ static void slc_encaps(struct slcan *sl, struct can_frame *cf) ...@@ -267,8 +305,8 @@ static void slc_encaps(struct slcan *sl, struct can_frame *cf)
* 14 Oct 1994 Dmitry Gorodchanin. * 14 Oct 1994 Dmitry Gorodchanin.
*/ */
set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
actual = sl->tty->ops->write(sl->tty, sl->xbuff, strlen(sl->xbuff)); actual = sl->tty->ops->write(sl->tty, sl->xbuff, pos - sl->xbuff);
sl->xleft = strlen(sl->xbuff) - actual; sl->xleft = (pos - sl->xbuff) - actual;
sl->xhead = sl->xbuff + actual; sl->xhead = sl->xbuff + actual;
sl->dev->stats.tx_bytes += cf->can_dlc; sl->dev->stats.tx_bytes += cf->can_dlc;
} }
......
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