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m_config: fix build with emulated stdatomic

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C11 can access atomic variables normally (in which case they use the
strictest memory access semantics). But the mpv stdatomic wrapper for
C99 compilers does not allow it, because it couldn't give any
guarantees. This means we always need to access them with atomic macros.

While we're at, use relaxed semantics for the m_config_cache field,
since because it's accessed from a single thread only (essentially
used in a non-atomic way). Switch the comparison arguments to make the
formatting look slightly less weird.
This commit is contained in:
wm4 2018-05-21 19:54:21 +02:00
parent 1a86bb59df
commit 0317d7350e
1 changed files with 3 additions and 2 deletions

5
options/m_config.c
View File

@ -1314,7 +1314,7 @@ static bool update_options(struct m_config_data *dst, struct m_config_data *src)
struct m_group_data *gdst = m_config_gdata(dst, n);
assert(gsrc && gdst);
if (gsrc->ts <= gdst->ts)
if (gdst->ts >= gsrc->ts)
continue;
gdst->ts = gsrc->ts;
res = true;
@ -1337,7 +1337,8 @@ bool m_config_cache_update(struct m_config_cache *cache)
// Using atomics and checking outside of the lock - it's unknown whether
// this makes it faster or slower. Just cargo culting it.
if (atomic_load(&shadow->data->ts) <= cache->data->ts)
if (atomic_load_explicit(&cache->data->ts, memory_order_relaxed) >=
atomic_load(&shadow->data->ts))
return false;
pthread_mutex_lock(&shadow->lock);