Fix slave FSM starvation and EoE NULL pointer dereference in master

[Copilot]

Two independent bugs in the EtherCAT master: one causing all slave FSMs after a pending datagram to be silently skipped, and one causing a NULL pointer dereference in the EoE failure path.

Changes

• master/master.c — ec_master_exec_slave_fsms(): return → continue when a slave FSM's datagram is still in INIT/QUEUED/SENT state. Using return caused the entire loop to exit early, starving all subsequent FSMs in fsm_exec_list for that cycle.

// Before: bails out of the entire loop
if (fsm->datagram->state == EC_DATAGRAM_INIT || ...) {
    return;  // all remaining FSMs skipped
}

// After: skips only the blocked FSM
    continue;

• master/fsm_slave.c — EoE failure path: Fixed typo where fsm->soe_request->state was written inside the if (fsm->eoe_request) guard. When fsm->soe_request is NULL (but fsm->eoe_request is not), this dereferences a NULL pointer.

// Before (wrong pointer):
if (fsm->eoe_request) {
    fsm->soe_request->state = EC_INT_REQUEST_FAILURE;  // NULL deref if soe_request == NULL
}

// After:
if (fsm->eoe_request) {
    fsm->eoe_request->state = EC_INT_REQUEST_FAILURE;
}

Original prompt

Two bugs to fix:

Bug 1: ec_master_exec_slave_fsms() in master/master.c (line ~1276)

The function iterates over master->fsm_exec_list but uses return when a FSM's datagram is still pending (states INIT/QUEUED/SENT). This blocks ALL remaining FSMs in the list from executing. It should use continue instead to skip that FSM and process the rest.

Current problematic code (around line 1293-1298):

if (fsm->datagram->state == EC_DATAGRAM_INIT ||
        fsm->datagram->state == EC_DATAGRAM_QUEUED ||
        fsm->datagram->state == EC_DATAGRAM_SENT) {
    // previous datagram was not sent or received yet.
    // wait until next thread execution
    return;  // BUG: should be continue
}

Change return; to continue; so other slave FSMs can still be processed.

Bug 2: EoE typo in master/fsm_slave.c

There is a typo where fsm->soe_request->state is used instead of fsm->eoe_request->state when checking EoE request state. This causes a potential NULL pointer dereference. Find the EoE request handling section and fix soe_request to eoe_request where it's clearly in an EoE context.

This pull request was created from Copilot chat.

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