Date: Wed, 29 Jun 2022 18:32:30 +0200 From: Thomas Stüfe <thomas.stuefe@...il.com> To: musl@...ts.openwall.com Subject: Re: Question about calloc, free in CPU_ALLOC and CPU_FREE On Wed, Jun 29, 2022 at 6:11 PM Markus Wichmann <nullplan@....net> wrote: > On Wed, Jun 29, 2022 at 05:49:55PM +0200, Thomas Stüfe wrote: > > Greetings, > > > > I have a small question about the way muslc implements the CPU_ALLOC and > > CPU_FREE macros. > > > > I see them defined in sched.h as: > > > > #define CPU_ALLOC(n) ((cpu_set_t *)calloc(1,CPU_ALLOC_SIZE(n))) > > #define CPU_FREE(set) free(set) > > > > whereas the glibc defines them as calls to functions __sched_cpu_alloc() > > and __sched_cpufree(): > > > > #define __CPU_ALLOC(count) __sched_cpualloc (count) > > #define __CPU_FREE(cpuset) __sched_cpufree (cpuset) > > > > in the end both variants allocate from C-heap, but the muslc variant gets > > inlined directly into the calling code. If that calling code has a > function > > "free" or "calloc" (okay, less likely) these get called instead. Could > also > > be a class local method in C++. > > > > That would be invalid. calloc() and free() are names defined in the C > standard, so no user defined macro or function can have those names. > > I don't know about you point about C++, though. Could be conceivably > worked around by using the :: operator, but that is only valid in C++, > so we'd have to #ifdef it. > > > I realize this is not a big issue. But would it not be safer to do as the > > glibc does in this case? > > > > Not really; if someone wants to use reserved names, there is little > reason to presume that "calloc" is any safer than "__sched_cpualloc". > > > Thank you, > > > > Thomas > > Ciao, > Markus > Thanks a lot for the quick response, Markus. I'm with the OpenJDK project, and the VM crashes on Alpine because of this issue (https://bugs.openjdk.org/browse/JDK-8289477). But I don't think muslc does anything wrong, and the fix is very simple (now that I know what happens). Cheers, Thomas Content of type "text/html" skipped
Powered by blists - more mailing lists
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.