possible dsm bug in dsm_attach()

Hi,

dsm_attach() does the following:
nitems = dsm_control->nitems;for (i = 0; i < nitems; ++i){    /* If the reference count is 0, the slot is actually
unused.*/    if (dsm_control->item[i].refcnt == 0)        continue;
 
    /*     * If the reference count is 1, the slot is still in use, but the     * segment is in the process of going
away. Treat that as if we     * didn't find a match.     */    if (dsm_control->item[i].refcnt == 1)        break;
 
    /* Otherwise, if the descriptor matches, we've found a match. */    if (dsm_control->item[i].handle == seg->handle)
  {        dsm_control->item[i].refcnt++;        seg->control_slot = i;        break;    }}
 

The break because of refcnt == 1 doesn't generally seem to be a good
idea. Why are we bailing if there's *any* segment that's in the process
of being removed? I think the check should be there *after* the
dsm_control->item[i].handle == seg->handle check?

Greetings,

Andres Freund

-- Andres Freund                       http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
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