From: Phil Sutter <phil@nwl.cc>
To: Thomas Haller <thaller@redhat.com>
Cc: NetFilter <netfilter-devel@vger.kernel.org>
Subject: Re: [PATCH nft 2/4] gmputil: add nft_gmp_free() to free strings from mpz_get_str()
Date: Wed, 20 Sep 2023 18:04:42 +0200 [thread overview]
Message-ID: <ZQsYGpnBigZ8ETX2@orbyte.nwl.cc> (raw)
In-Reply-To: <9d90f25dd24e76567e784c93b2a1a5493c14e379.camel@redhat.com>
On Wed, Sep 20, 2023 at 04:46:12PM +0200, Thomas Haller wrote:
> On Wed, 2023-09-20 at 16:05 +0200, Phil Sutter wrote:
> > On Wed, Sep 20, 2023 at 03:13:39PM +0200, Thomas Haller wrote:
> > >
> > > + mp_get_memory_functions(NULL, NULL, &free_fcn);
> >
> > Do we have to expect the returned pointer to change at run-time?
> > Because
> > if not, couldn't one make free_fcn static and call
> > mp_get_memory_functions() only if it's NULL?
>
> Hi Phil,
>
>
> no, it's not expected to EVER change. Users must not change
> mp_set_memory_functions() after any GMP objects were allocated,
> otherwise there would be a mixup of allocators and crashes ahead.
>
> However, I didn't cache the value, because I don't want to use global
> data without atomic compare-exchange (or thread-local). Doing it
> without regard of thread-safety so would be a code smell (even if
> probably not an issue in practice). And getting it with atomic/thread-
> local would be cumbersome. It's hard to ensure a code base has no
> threading issues, when having lots of places that "most likely are
> 99.99% fine (but not 100%)". Hence, I want to avoid the global.
OK, thanks.
> I think the call to mp_get_memory_functions() should be cheap.
Yes, the function is indeed very simple.
Cheers, Phil
next prev parent reply other threads:[~2023-09-20 16:04 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-20 13:13 [PATCH nft 0/4] remove xfree() and add free_const()+nft_gmp_free() Thomas Haller
2023-09-20 13:13 ` [PATCH nft 1/4] datatype: don't return a const string from cgroupv2_get_path() Thomas Haller
2023-09-20 13:13 ` [PATCH nft 2/4] gmputil: add nft_gmp_free() to free strings from mpz_get_str() Thomas Haller
2023-09-20 14:05 ` Phil Sutter
2023-09-20 14:46 ` Thomas Haller
2023-09-20 16:04 ` Phil Sutter [this message]
2023-09-20 13:13 ` [PATCH nft 3/4] all: add free_const() and use it instead of xfree() Thomas Haller
2023-09-20 14:13 ` Phil Sutter
2023-09-20 16:06 ` Pablo Neira Ayuso
2023-09-20 16:49 ` Phil Sutter
2023-09-20 16:52 ` Pablo Neira Ayuso
2023-09-20 18:03 ` Thomas Haller
2023-09-20 18:22 ` Phil Sutter
2023-09-20 19:48 ` Thomas Haller
2023-09-20 22:50 ` Phil Sutter
2023-09-21 9:08 ` Thomas Haller
2023-09-20 13:13 ` [PATCH nft 4/4] all: remove xfree() and use plain free() Thomas Haller
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