recent changes to pthread_fork.c:fork() cause static linking to fail if the app provides its own malloc()

["Greg A. Woods" <woods%planix.ca@localhost>]

I think it is the following change (and perhaps more similar/related
changes) which breaks static linking of applications which wish to
supply their own implementation of malloc(), and which call, e.g.,
fork():

This is because fork() now calls _malloc_prefork(), and if the
application's replacement does not offer this function (as it should
not), then the linker is forced to drag in all of jemalloc.o.  This of
course happens even if the application is not multi-threaded and is not
linking against -lpthread.

revision 1.15
date: 2020-05-15 07:37:21 -0700;  author: joerg;  state: Exp;  lines: +6 -2;  commitid: 85oo6pCrePrJul8C;
Hook up proper fork lock handling for malloc:
- lock all relevant mutexes just before fork
- unlock all mutexes just after fork in the parent
- full reinit non-spinlocks in the child
This is not using the normal pthread_atfork interface to ensure order of
operation, malloc is used as implementation detail too often.


For example, here static linking pkgsrc/shells/heirloom-sh:

ld: /usr/lib/libc.a(jemalloc.o): in function `malloc':
/build/src-current/external/bsd/jemalloc/lib/../dist/src/jemalloc.c:2056: multiple definition of `malloc'; mapmalloc.o:/var/package-obj/root/shells/heirloom-sh/work/heirloom-sh-050706/mapmalloc.c:195: first defined here
ld: /usr/lib/libc.a(jemalloc.o): in function `calloc':
/build/src-current/external/bsd/jemalloc/lib/../dist/src/jemalloc.c:2154: multiple definition of `calloc'; mapmalloc.o:/var/package-obj/root/shells/heirloom-sh/work/heirloom-sh-050706/mapmalloc.c:381: first defined here
ld: /usr/lib/libc.a(jemalloc.o): in function `realloc':
/build/src-current/external/bsd/jemalloc/lib/../dist/src/jemalloc.c:2326: multiple definition of `realloc'; mapmalloc.o:/var/package-obj/root/shells/heirloom-sh/work/heirloom-sh-050706/mapmalloc.c:330: first defined here
ld: /usr/lib/libc.a(jemalloc.o): in function `free':
/build/src-current/external/bsd/jemalloc/lib/../dist/src/jemalloc.c:2416: multiple definition of `free'; mapmalloc.o:/var/package-obj/root/shells/heirloom-sh/work/heirloom-sh-050706/mapmalloc.c:303: first defined here


Should I send-pr this?  Is there any possibility of an "easy" fix?

--
					Greg A. Woods <gwoods%acm.org@localhost>

Kelowna, BC     +1 250 762-7675           RoboHack <woods%robohack.ca@localhost>
Planix, Inc. <woods%planix.com@localhost>     Avoncote Farms <woods%avoncote.ca@localhost>

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