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drivers: modem: verify send semaphore before taking any action

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Semaphore argument is checked only after requested command is already
sent over modem interface. It makes little sense to return -EINVAL when
half of the requested operation (send) has already been done.

Check timeout and semaphore arguments just on the beginning of
function. Return -EINVAL early, before sending any data or taking any
locks.

Clear out 'sem' variable when there is no need to wait. Use this
variable later on as an indication to actually wait on semaphore or not.

Signed-off-by: Marcin Niestroj <m.niestroj@grinn-global.com>
This commit is contained in:
Marcin Niestroj 2020-11-19 19:41:53 +01:00 • committed by Anas Nashif
commit 67976f8686
1 changed files with 17 additions and 17 deletions
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34
drivers/modem/modem_cmd_handler.c
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@ -477,7 +477,15 @@ static int _modem_cmd_send(struct modem_iface *iface,
struct modem_cmd_handler_data *data;
int ret;
if (!iface || !handler || !handler->cmd_handler_data || !buf) {
if (!iface || !handler || !handler->cmd_handler_data || !buf || !sem) {
return -EINVAL;
}
if (K_TIMEOUT_EQ(timeout, K_NO_WAIT)) {
/* semaphore is not needed if there is no timeout */
sem = NULL;
} else if (!sem) {
/* cannot respect timeout without semaphore */
return -EINVAL;
}
@ -509,23 +517,15 @@ static int _modem_cmd_send(struct modem_iface *iface,
iface->write(iface, buf, strlen(buf));
iface->write(iface, data->eol, data->eol_len);
if (K_TIMEOUT_EQ(timeout, K_NO_WAIT)) {
ret = 0;
goto exit;
}
if (sem) {
k_sem_reset(sem);
ret = k_sem_take(sem, timeout);
if (!sem) {
ret = -EINVAL;
goto exit;
}
k_sem_reset(sem);
ret = k_sem_take(sem, timeout);
if (ret == 0) {
ret = data->last_error;
} else if (ret == -EAGAIN) {
ret = -ETIMEDOUT;
if (ret == 0) {
ret = data->last_error;
} else if (ret == -EAGAIN) {
ret = -ETIMEDOUT;
}
}
exit: