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Be conservative about alignment requirements of struct epoll_event.
Use MAXALIGN size/alignment to guarantee that later uses of memory are aligned correctly. E.g. epoll_event might need 8 byte alignment on some platforms, but earlier allocations like WaitEventSet and WaitEvent might not sized to guarantee that when purely using sizeof(). Found by myself while testing on an Sun Ultra 5 (Sparc IIi) with some editorializing by Andres Freund. In passing fix a couple typos in the area
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-12
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+18
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src/backend/storage/ipc/latch.c

+18-12
Original file line numberDiff line numberDiff line change
@@ -475,7 +475,7 @@ ResetLatch(volatile Latch *latch)
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/*
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* Create a WaitEventSet with space for nevents different events to wait for.
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*
478-
* These events can then efficiently waited upon together, using
478+
* These events can then be efficiently waited upon together, using
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* WaitEventSetWait().
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*/
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WaitEventSet *
@@ -485,35 +485,41 @@ CreateWaitEventSet(MemoryContext context, int nevents)
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char *data;
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Size sz = 0;
487487

488-
sz += sizeof(WaitEventSet);
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sz += sizeof(WaitEvent) * nevents;
488+
/*
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* Use MAXALIGN size/alignment to guarantee that later uses of memory are
490+
* aligned correctly. E.g. epoll_event might need 8 byte alignment on some
491+
* platforms, but earlier allocations like WaitEventSet and WaitEvent
492+
* might not sized to guarantee that when purely using sizeof().
493+
*/
494+
sz += MAXALIGN(sizeof(WaitEventSet));
495+
sz += MAXALIGN(sizeof(WaitEvent) * nevents);
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#if defined(WAIT_USE_EPOLL)
492-
sz += sizeof(struct epoll_event) * nevents;
498+
sz += MAXALIGN(sizeof(struct epoll_event) * nevents);
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#elif defined(WAIT_USE_POLL)
494-
sz += sizeof(struct pollfd) * nevents;
500+
sz += MAXALIGN(sizeof(struct pollfd) * nevents);
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#elif defined(WAIT_USE_WIN32)
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/* need space for the pgwin32_signal_event */
497-
sz += sizeof(HANDLE) * (nevents + 1);
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sz += MAXALIGN(sizeof(HANDLE) * (nevents + 1));
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#endif
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data = (char *) MemoryContextAllocZero(context, sz);
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set = (WaitEventSet *) data;
503-
data += sizeof(WaitEventSet);
509+
data += MAXALIGN(sizeof(WaitEventSet));
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set->events = (WaitEvent *) data;
506-
data += sizeof(WaitEvent) * nevents;
512+
data += MAXALIGN(sizeof(WaitEvent) * nevents);
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#if defined(WAIT_USE_EPOLL)
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set->epoll_ret_events = (struct epoll_event *) data;
510-
data += sizeof(struct epoll_event) * nevents;
516+
data += MAXALIGN(sizeof(struct epoll_event) * nevents);
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#elif defined(WAIT_USE_POLL)
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set->pollfds = (struct pollfd *) data;
513-
data += sizeof(struct pollfd) * nevents;
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data += MAXALIGN(sizeof(struct pollfd) * nevents);
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#elif defined(WAIT_USE_WIN32)
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set->handles = (HANDLE) data;
516-
data += sizeof(HANDLE) * nevents;
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data += MAXALIGN(sizeof(HANDLE) * nevents);
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#endif
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set->latch = NULL;
@@ -616,7 +622,7 @@ AddWaitEventToSet(WaitEventSet *set, uint32 events, pgsocket fd, Latch *latch,
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if (set->latch)
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elog(ERROR, "cannot wait on more than one latch");
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if ((events & WL_LATCH_SET) != WL_LATCH_SET)
619-
elog(ERROR, "latch events only spuport being set");
625+
elog(ERROR, "latch events only support being set");
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}
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else
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{

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