From ab91d32c1b23ea92b988d5618db2938a8c5dc63f Mon Sep 17 00:00:00 2001 From: Boris Kolpackov Date: Fri, 26 May 2023 07:22:40 +0200 Subject: Avoid group linkup deadlocks for dynamic and pattern-static members --- libbuild2/adhoc-rule-regex-pattern.cxx | 36 ++++++++++++++++++++++------------ 1 file changed, 23 insertions(+), 13 deletions(-) (limited to 'libbuild2/adhoc-rule-regex-pattern.cxx') diff --git a/libbuild2/adhoc-rule-regex-pattern.cxx b/libbuild2/adhoc-rule-regex-pattern.cxx index 0f2ecc3..c4b4cab 100644 --- a/libbuild2/adhoc-rule-regex-pattern.cxx +++ b/libbuild2/adhoc-rule-regex-pattern.cxx @@ -400,21 +400,31 @@ namespace build2 if (find (ms.begin (), ms.end (), &t) != ms.end ()) continue; - // We can only update the group under lock. + // Check if we already belong to this group. Note that this not a + // mere optimization since we may be in the member->group->member + // chain and trying to lock the member the second time would + // deadlock (this can be triggered, for example, by dist, which sort + // of depends on such members directly @@ maybe this should be fixed + // there?). // - target_lock tl (lock (a, t)); - - if (!tl) - fail << "group " << *g << " member " << t << " is already matched" << - info << "static group members specified by pattern rules cannot " - << "be used as prerequisites directly, only via group"; - - if (t.group == nullptr) - tl.target->group = g; - else if (t.group != g) + if (t.group != g) // Note: atomic. { - fail << "group " << *g << " member " << t - << " is already member of group " << *t.group; + // We can only update the group under lock. + // + target_lock tl (lock (a, t)); + + if (!tl) + fail << "group " << *g << " member " << t << " is already matched" << + info << "static group members specified by pattern rules cannot " + << "be used as prerequisites directly, only via group"; + + if (t.group == nullptr) + tl.target->group = g; + else if (t.group != g) + { + fail << "group " << *g << " member " << t + << " is already member of group " << *t.group; + } } } -- cgit v1.1