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| author | Eric Wong <e@80x24.org> | 2022-08-15 21:22:17 +0000 |
|---|---|---|
| committer | Eric Wong <mwrap-public@80x24.org> | 2022-08-22 17:11:39 +0000 |
| commit | 32c9a817cab2e28534de62ff62c4686b520fb3fe (patch) | |
| tree | 0f6cb8ebbb1f7b16d32bbea0c6151f984f05a31a /ext/mwrap/mwrap.c | |
| parent | 4a90540056afce4f73da97300e6709993355fe4f (diff) | |
| download | mwrap-32c9a817cab2e28534de62ff62c4686b520fb3fe.tar.gz | |
urcu v0.11.4+ introduced commit 7ca7fe9c03 (Make temporary variable in _rcu_dereference non-const, 2021-07-29) which conflicts with our use of _LGPL_SOURCE. In retrospect, CMM_LOAD_SHARED and CMM_STORE_SHARED seem sufficient for our use of the `totals' cds_lfht pointer since the constructur should always fire before any threads are running. This is fixed in urcu v0.12.4 and v0.13.2 (released 2022-08-18) but I suspect older versions will live on in enterprise/LTS distros for a long while. Link: https://lore.kernel.org/lttng-dev/20220809181927.GA3718@dcvr/
Diffstat (limited to 'ext/mwrap/mwrap.c')
| -rw-r--r-- | ext/mwrap/mwrap.c | 19 |
1 files changed, 9 insertions, 10 deletions
diff --git a/ext/mwrap/mwrap.c b/ext/mwrap/mwrap.c index 4575e34..477b1cb 100644 --- a/ext/mwrap/mwrap.c +++ b/ext/mwrap/mwrap.c @@ -139,8 +139,8 @@ __attribute__((constructor)) static void resolve_malloc(void) _exit(1); } #endif /* !FreeBSD */ - totals = lfht_new(); - if (!totals) + CMM_STORE_SHARED(totals, lfht_new()); + if (!CMM_LOAD_SHARED(totals)) fprintf(stderr, "failed to allocate totals table\n"); err = pthread_atfork(call_rcu_before_fork, @@ -375,7 +375,7 @@ static struct src_loc *totals_add_rcu(struct src_loc *k) struct cds_lfht *t; again: - t = rcu_dereference(totals); + t = CMM_LOAD_SHARED(totals); if (!t) goto out_unlock; cds_lfht_lookup(t, k->hval, loc_eq, k, &iter); cur = cds_lfht_iter_get_node(&iter); @@ -417,7 +417,7 @@ static struct src_loc *update_stats_rcu_lock(size_t size, uintptr_t caller) static const size_t xlen = sizeof(caller); char *dst; - if (caa_unlikely(!totals)) return 0; + if (caa_unlikely(!CMM_LOAD_SHARED(totals))) return 0; if (locating++) goto out; /* do not recurse into another *alloc */ uatomic_add(&total_bytes_inc, size); @@ -808,7 +808,7 @@ static void *dump_to_file(void *x) ++locating; rcu_read_lock(); - t = rcu_dereference(totals); + t = CMM_LOAD_SHARED(totals); if (!t) goto out_unlock; cds_lfht_for_each_entry(t, &iter, l, hnode) { @@ -877,7 +877,7 @@ static void *totals_reset(void *ign) uatomic_set(&total_bytes_dec, 0); rcu_read_lock(); - t = rcu_dereference(totals); + t = CMM_LOAD_SHARED(totals); cds_lfht_for_each_entry(t, &iter, l, hnode) { uatomic_set(&l->total, 0); uatomic_set(&l->allocations, 0); @@ -945,7 +945,7 @@ static VALUE dump_each_rcu(VALUE x) struct cds_lfht_iter iter; struct src_loc *l; - t = rcu_dereference(totals); + t = CMM_LOAD_SHARED(totals); cds_lfht_for_each_entry(t, &iter, l, hnode) { VALUE v[6]; if (l->total <= a->min) continue; @@ -1049,9 +1049,9 @@ static VALUE mwrap_aref(VALUE mod, VALUE loc) if (!k) return val; + t = CMM_LOAD_SHARED(totals); + if (!t) return val; rcu_read_lock(); - t = rcu_dereference(totals); - if (!t) goto out_unlock; cds_lfht_lookup(t, k->hval, loc_eq, k, &iter); cur = cds_lfht_iter_get_node(&iter); @@ -1059,7 +1059,6 @@ static VALUE mwrap_aref(VALUE mod, VALUE loc) l = caa_container_of(cur, struct src_loc, hnode); val = TypedData_Wrap_Struct(cSrcLoc, &src_loc_type, l); } -out_unlock: rcu_read_unlock(); return val; } |