Wed 28 May 2008 11:08:22 AM UTC, original submission:
Hello..
On small values of SYS_MBOX_SIZE (40 and less)
mbox reader and writer threads stops on sys_arch_sem_wait(mbox->mail, 0);
Solution for this bug is separate semaphores.
First one - for busy
Second - for empty event
Like this...
struct sys_mbox {
int first, last;
void *msgs[SYS_MBOX_SIZE];
struct sys_sem *mutex;
int wait_send;
int mbox_size;
struct sys_sem *can_post_mail;
struct sys_sem *can_fetch_mail;
};
sys_mbox_post(struct sys_mbox mbox, void msg)
{
u8_t first;
sys_sem_wait(mbox->mutex);
LWIP_DEBUGF(SYS_DEBUG, ("sys_mbox_post: mbox %p msg %p\n", (void )mbox, (void )msg));
while ((mbox->last + 1) >= (mbox->first + SYS_MBOX_SIZE)) {
mbox->wait_send++;
sys_sem_signal(mbox->mutex);
- sys_arch_sem_wait(mbox->mail, 0);
+ sys_arch_sem_wait(mbox->can_post_mail, 0);
sys_arch_sem_wait(mbox->mutex, 0);
mbox->wait_send--;
}
mbox->msgs[mbox->last % SYS_MBOX_SIZE] = msg;
if (mbox->last == mbox->first) {
first = 1;
} else {
first = 0;
}
mbox->last++;
if (first) {
- sys_sem_signal(mbox->mail)
+ sys_sem_signal(mbox->can_fetch_mail);
}
sys_sem_signal(mbox->mutex);
}
u32_t
sys_arch_mbox_fetch(struct sys_mbox mbox, void *msg, u32_t timeout)
{
u32_t time = 0;
/* The mutex lock is quick so we don't bother with the timeout
stuff here. */
sys_arch_sem_wait(mbox->mutex, 0);
while (mbox->first == mbox->last) {
sys_sem_signal(mbox->mutex);
/* We block while waiting for a mail to arrive in the mailbox. We
must be prepared to timeout. */
if (timeout != 0) {
- time = sys_arch_sem_wait(mbox->mail, timeout);
+ time = sys_arch_sem_wait(mbox->can_fetch_mail, timeout);
if (time == SYS_ARCH_TIMEOUT) {
return SYS_ARCH_TIMEOUT;
}
} else {
sys_arch_sem_wait(mbox->mail, 0);
sys_arch_sem_wait(mbox->can_fetch_mail, 0);
}
sys_arch_sem_wait(mbox->mutex, 0);
}
if (msg != NULL) {
LWIP_DEBUGF(SYS_DEBUG, ("sys_mbox_fetch: mbox %p msg %p\n", (void )mbox, msg));
*msg = mbox->msgs[mbox->first % SYS_MBOX_SIZE];
}
else{
LWIP_DEBUGF(SYS_DEBUG, ("sys_mbox_fetch: mbox %p, null msg\n", (void *)mbox));
}
mbox->first++;
if (mbox->wait_send) {
- sys_sem_signal(mbox->mail);
+ sys_sem_signal(mbox->can_post_mail)
}
sys_sem_signal(mbox->mutex);
return time;
}
|