Searched hist:130289 (Results 1 - 1 of 1) sorted by relevance
| /freebsd-11-stable/sys/kern/ | ||
| H A D | uipc_mbuf.c | diff 130289 Wed Jun 09 22:04:27 MDT 2004 bmilekic Plug a race where upon free this scenario could occur: (time grows downward) thread 1 thread 2 ------------|------------ dec ref_cnt | | dec ref_cnt <-- ref_cnt now zero cmpset | free all | return | | alloc again,| reuse prev | ref_cnt | | cmpset, read | already freed | ref_cnt ------------|------------ This should fix that by performing only a single atomic test-and-set that will serve to decrement the ref_cnt, only if it hasn't changed since the earlier read, otherwise it'll loop and re-read. This forces ordering of decrements so that truly the thread which did the LAST decrement is the one that frees. This is how atomic-instruction-based refcnting should probably be handled. Submitted by: Julian Elischer |
Completed in 90 milliseconds