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| /freebsd-10.3-release/sys/rpc/ | ||
| H A D | clnt_dg.c | diff 227059 Thu Nov 03 14:39:42 MDT 2011 rmacklem Both a crash reported on freebsd-current on Oct. 18 under the subject heading "mtx_lock() of destroyed mutex on NFS" and PR# 156168 appear to be caused by clnt_dg_destroy() closing down the socket prematurely. When to close down the socket is controlled by a reference count (cs_refs), but clnt_dg_create() checks for sb_upcall being non-NULL to decide if a new socket is needed. I believe the crashes were caused by the following race: clnt_dg_destroy() finds cs_refs == 0 and decides to delete socket clnt_dg_destroy() then loses race with clnt_dg_create() for acquisition of the SOCKBUF_LOCK() clnt_dg_create() finds sb_upcall != NULL and increments cs_refs to 1 clnt_dg_destroy() then acquires SOCKBUF_LOCK(), sets sb_upcall to NULL and destroys socket This patch fixes the above race by changing clnt_dg_destroy() so that it acquires SOCKBUF_LOCK() before testing cs_refs. Tested by: bz PR: 156168 Reviewed by: dfr MFC after: 2 weeks |
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