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Commita3b3076

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Be conservative about alignment requirements of struct epoll_event.
Use MAXALIGN size/alignment to guarantee that later uses of memory arealigned correctly. E.g. epoll_event might need 8 byte alignment on someplatforms, but earlier allocations like WaitEventSet and WaitEvent mightnot sized to guarantee that when purely using sizeof().Found by myself while testing on an Sun Ultra 5 (Sparc IIi) with someeditorializing by Andres Freund.In passing fix a couple typos in the area
1 parent4edb7bd commita3b3076

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1 file changed

+18
-12
lines changed

1 file changed

+18
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lines changed

‎src/backend/storage/ipc/latch.c

Lines changed: 18 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -475,7 +475,7 @@ ResetLatch(volatile Latch *latch)
475475
/*
476476
* Create a WaitEventSet with space for nevents different events to wait for.
477477
*
478-
* These events can then efficiently waited upon together, using
478+
* These events can thenbeefficiently waited upon together, using
479479
* WaitEventSetWait().
480480
*/
481481
WaitEventSet*
@@ -485,35 +485,41 @@ CreateWaitEventSet(MemoryContext context, int nevents)
485485
char*data;
486486
Sizesz=0;
487487

488-
sz+=sizeof(WaitEventSet);
489-
sz+=sizeof(WaitEvent)*nevents;
488+
/*
489+
* 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);
490496

491497
#if defined(WAIT_USE_EPOLL)
492-
sz+=sizeof(structepoll_event)*nevents;
498+
sz+=MAXALIGN(sizeof(structepoll_event)*nevents);
493499
#elif defined(WAIT_USE_POLL)
494-
sz+=sizeof(structpollfd)*nevents;
500+
sz+=MAXALIGN(sizeof(structpollfd)*nevents);
495501
#elif defined(WAIT_USE_WIN32)
496502
/* need space for the pgwin32_signal_event */
497-
sz+=sizeof(HANDLE)* (nevents+1);
503+
sz+=MAXALIGN(sizeof(HANDLE)* (nevents+1));
498504
#endif
499505

500506
data= (char*)MemoryContextAllocZero(context,sz);
501507

502508
set= (WaitEventSet*)data;
503-
data+=sizeof(WaitEventSet);
509+
data+=MAXALIGN(sizeof(WaitEventSet));
504510

505511
set->events= (WaitEvent*)data;
506-
data+=sizeof(WaitEvent)*nevents;
512+
data+=MAXALIGN(sizeof(WaitEvent)*nevents);
507513

508514
#if defined(WAIT_USE_EPOLL)
509515
set->epoll_ret_events= (structepoll_event*)data;
510-
data+=sizeof(structepoll_event)*nevents;
516+
data+=MAXALIGN(sizeof(structepoll_event)*nevents);
511517
#elif defined(WAIT_USE_POLL)
512518
set->pollfds= (structpollfd*)data;
513-
data+=sizeof(structpollfd)*nevents;
519+
data+=MAXALIGN(sizeof(structpollfd)*nevents);
514520
#elif defined(WAIT_USE_WIN32)
515521
set->handles= (HANDLE)data;
516-
data+=sizeof(HANDLE)*nevents;
522+
data+=MAXALIGN(sizeof(HANDLE)*nevents);
517523
#endif
518524

519525
set->latch=NULL;
@@ -616,7 +622,7 @@ AddWaitEventToSet(WaitEventSet *set, uint32 events, pgsocket fd, Latch *latch,
616622
if (set->latch)
617623
elog(ERROR,"cannot wait on more than one latch");
618624
if ((events&WL_LATCH_SET)!=WL_LATCH_SET)
619-
elog(ERROR,"latch events onlyspuport being set");
625+
elog(ERROR,"latch events onlysupport being set");
620626
}
621627
else
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{

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