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canbus: isotp: fix net_buf usage in recv function

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isotp_recv and the called pull_frags functions were violating the
net_buf API by interacting directly with net_buf fragments pulled from
a k_fifo.

This commit reworks the isotp_recv function. The currently processed
net_buf is stored in an additional context variable so that reading from
it can be continued in the next call to isotp_recv if not all fragments
could be fit into the provided uint8_t *data buffer.

Fixes #40070

Signed-off-by: Martin Jäger <martin@libre.solar>
This commit is contained in:
Martin Jäger 2021-11-08 12:16:28 +01:00 • committed by Johan Hedberg
commit 27fc74feff
2 changed files with 24 additions and 55 deletions
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2
include/canbus/isotp.h
View file

@ -406,6 +406,8 @@ struct isotp_recv_ctx {
const struct device *can_dev;
struct net_buf *buf;
struct net_buf *act_frag;
/* buffer currently processed in isotp_recv */
struct net_buf *recv_buf;
sys_snode_t alloc_node;
uint32_t length;
int error_nr;

77
subsys/canbus/isotp/isotp.c
View file

@ -70,17 +70,6 @@ static void receive_ff_sf_pool_free(struct net_buf *buf)
}
}
static inline int _k_fifo_wait_non_empty(struct k_fifo *fifo,
k_timeout_t timeout)
{
struct k_poll_event events[] = {
K_POLL_EVENT_INITIALIZER(K_POLL_TYPE_FIFO_DATA_AVAILABLE,
K_POLL_MODE_NOTIFY_ONLY, fifo),
};
return k_poll(events, ARRAY_SIZE(events), timeout);
}
static inline void receive_report_error(struct isotp_recv_ctx *ctx, int err)
{
ctx->state = ISOTP_RX_STATE_ERR;
@ -692,62 +681,40 @@ int isotp_recv_net(struct isotp_recv_ctx *ctx, struct net_buf **buffer,
return *(uint32_t *)net_buf_user_data(buf);
}
static inline void pull_frags(struct k_fifo *fifo, struct net_buf *buf,
size_t len)
{
size_t rem_len = len;
struct net_buf *frag = buf;
/* frags to be removed */
while (frag && (frag->len <= rem_len)) {
rem_len -= frag->len;
frag = frag->frags;
k_fifo_get(fifo, K_NO_WAIT);
}
if (frag) {
/* Start of frags to be preserved */
net_buf_ref(frag);
net_buf_pull(frag, rem_len);
}
net_buf_unref(buf);
}
int isotp_recv(struct isotp_recv_ctx *ctx, uint8_t *data, size_t len,
k_timeout_t timeout)
{
size_t num_copied, frags_len;
struct net_buf *buf;
int ret;
size_t copied, to_copy;
int err;
ret = _k_fifo_wait_non_empty(&ctx->fifo, timeout);
if (ret) {
if (ctx->error_nr) {
ret = ctx->error_nr;
if (!ctx->recv_buf) {
ctx->recv_buf = net_buf_get(&ctx->fifo, timeout);
if (!ctx->recv_buf) {
err = ctx->error_nr ? ctx->error_nr : ISOTP_RECV_TIMEOUT;
ctx->error_nr = 0;
return ret;
}
if (ret == -EAGAIN) {
return ISOTP_RECV_TIMEOUT;
return err;
}
return ISOTP_N_ERROR;
}
buf = k_fifo_peek_head(&ctx->fifo);
/* traverse fragments and delete them after copying the data */
copied = 0;
while (ctx->recv_buf && copied < len) {
to_copy = MIN(len - copied, ctx->recv_buf->len);
memcpy((uint8_t *)data + copied, ctx->recv_buf->data, to_copy);
if (!buf) {
return ISOTP_N_ERROR;
if (ctx->recv_buf->len == to_copy) {
/* point recv_buf to next frag */
ctx->recv_buf = net_buf_frag_del(NULL, ctx->recv_buf);
} else {
/* pull received data from remaining frag(s) */
net_buf_pull(ctx->recv_buf, to_copy);
}
copied += to_copy;
}
frags_len = net_buf_frags_len(buf);
num_copied = net_buf_linearize(data, len, buf, 0, len);
pull_frags(&ctx->fifo, buf, num_copied);
return num_copied;
return copied;
}
static inline void send_report_error(struct isotp_send_ctx *ctx, uint32_t err)