From 15f8ca326070dde083bd59618d4b77c24dde06a5 Mon Sep 17 00:00:00 2001 From: Sverker Eriksson Date: Thu, 25 Oct 2018 18:06:30 +0200 Subject: erts: Let lock checker allow trylock of same order for different lock instances. --- erts/emulator/beam/erl_lock_check.c | 25 ++++++++++++++++--------- 1 file changed, 16 insertions(+), 9 deletions(-) (limited to 'erts') diff --git a/erts/emulator/beam/erl_lock_check.c b/erts/emulator/beam/erl_lock_check.c index edcfcb4cd7..394e19f2fa 100644 --- a/erts/emulator/beam/erl_lock_check.c +++ b/erts/emulator/beam/erl_lock_check.c @@ -194,6 +194,12 @@ struct lc_locked_lock_t_ { unsigned int line; erts_lock_flags_t flags; erts_lock_options_t taken_options; + /* + * Pointer back to the lock instance if it exists or NULL for proc locks. + * If set, we use it to allow trylock of other lock instance + * but with identical lock order as an already locked lock. + */ + erts_lc_lock_t *lck; }; typedef struct { @@ -407,6 +413,10 @@ new_locked_lock(lc_thread_t* thr, ll->line = line; ll->flags = lck->flags; ll->taken_options = options; + if ((lck->flags & ERTS_LOCK_FLAGS_MASK_TYPE) == ERTS_LOCK_FLAGS_TYPE_PROCLOCK) + ll->lck = NULL; + else + ll->lck = lck; return ll; } @@ -1005,17 +1015,14 @@ erts_lc_trylock_force_busy_flg(erts_lc_lock_t *lck, erts_lock_options_t options) */ /* Check that we are not trying to lock this lock twice */ - while (1) { - if (order <= 0) { - if (order == 0) - lock_twice("Trylocking", thr, lck, options); - break; - } + do { + if (order == 0 && (ll->lck == lck || !ll->lck)) + lock_twice("Trylocking", thr, lck, options); ll = ll->prev; if (!ll) break; order = compare_locked_by_id_extra(ll, lck); - } + } while (order >= 0); #ifndef ERTS_LC_ALLWAYS_FORCE_BUSY_TRYLOCK_ON_LOCK_ORDER_VIOLATION /* We only force busy if a lock order violation would occur @@ -1064,8 +1071,8 @@ void erts_lc_trylock_flg_x(int locked, erts_lc_lock_t *lck, erts_lock_options_t for (tl_lck = thr->locked.last; tl_lck; tl_lck = tl_lck->prev) { int order = compare_locked_by_id_extra(tl_lck, lck); if (order <= 0) { - if (order == 0) - lock_twice("Trylocking", thr, lck, options); + if (order == 0 && (tl_lck->lck == lck || !tl_lck->lck)) + lock_twice("Trylocking", thr, lck, options); if (locked) { ll->next = tl_lck->next; ll->prev = tl_lck; -- cgit v1.2.3