Re: [libvirt] [PATCHv2] util: keep/use a bitmap of in-use macvtap devices

>> + retries = MACVLAN_MAX_ID + 1; >> + while (!ifnameCreated && retries) { >> virMutexLock(&virNetDevMacVLanCreateMutex); >> - for (c = 0; c < 8192; c++) { >> - snprintf(ifname, sizeof(ifname), pattern, c); >> - if ((ret = virNetDevExists(ifname)) < 0) { >> - virMutexUnlock(&virNetDevMacVLanCreateMutex); >> + reservedID = virNetDevMacVLanReserveID(reservedID, flags, false, true); >> + if (reservedID < 0) { >> + virMutexUnlock(&virNetDevMacVLanCreateMutex); >> + return -1; >> + } >> + snprintf(ifname, sizeof(ifname), pattern, reservedID); > Since you're changing this, snprintf returns -1 in case of error. Well, the man page says -1 is returned by the *printf functions "if an output error is encountered", which would include an I/O error (moot for snprintf() since it doesn't do any I/O) or a bad format string (but we're calling it with a literal format string that only includes a single %d, so it is known to be good). Checking the returned length is pointless too, since by definition the longest possible result of macvtap%d where the %d is guaranteed between 0 and 8192 is "macvtap8192", which is 12 characters - safely below the limit of IFNAMSIZ (16).