From: Siddhesh Poyarekar <siddhesh@gotplt.org>
To: Alexey Makhalov <amakhalov@vmware.com>, carlos@redhat.com
Cc: libc-alpha@sourceware.org
Subject: Re: [PATCH] Fix range check in do_tunable_update_val
Date: Tue, 26 Sep 2017 18:54:00 -0000 [thread overview]
Message-ID: <bc9f895c-75d7-f5e9-7cf2-45634052c9c7@gotplt.org> (raw)
In-Reply-To: <20170926183807.31788-1-amakhalov@vmware.com>
On Wednesday 27 September 2017 12:08 AM, Alexey Makhalov wrote:
> Current implementation of tunables does not set arena_max and arena_test
> values. Any value provided by glibc.malloc.arena_max and
> glibc.malloc.arena_test parameters is ignored.
>
> These tunables have minval value set to 1 (see elf/dl-tunables.list file)
> and undefined maxval value. In that case default value (which is 0. see
> scripts/gen-tunables.awk) is being used to set maxval.
>
> For instance, generated tunable_list[] entry for arena_max is:
> (gdb) p *cur
> $1 = {name = 0x7ffff7df6217 "glibc.malloc.arena_max",
> type = {type_code = TUNABLE_TYPE_SIZE_T, min = 1, max = 0},
> val = {numval = 0, strval = 0x0}, initialized = false,
> security_level = TUNABLE_SECLEVEL_SXID_IGNORE,
> env_alias = 0x7ffff7df622e "MALLOC_ARENA_MAX"}
>
> As a result, any value of glibc.malloc.arena_max is ignored by
> TUNABLE_SET_VAL_IF_VALID_RANGE macro
> __type min = (__cur)->type.min; <- initialized to 1
> __type max = (__cur)->type.max; <- initialized to 0!
> if (min == max) <- false
> {
> min = __default_min;
> max = __default_max;
> }
> if ((__type) (__val) >= min && (__type) (val) <= max) <- false
> {
> (__cur)->val.numval = val;
> (__cur)->initialized = true;
> }
>
> Assigning correct min/max values at a build time fixes a problem.
> Plus, a bit of optimization: Setting of default min/max values for the
> given type at a run time might be eliminated.
Thanks for the patch. Can you please clarify the status of your
copyright assignment (and Carlos verify it please)? I don't have access
to the copyright assignment list, so once that question is cleared, I'll
test and merge this patch.
Siddhesh
next prev parent reply other threads:[~2017-09-26 18:54 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-26 18:38 Alexey Makhalov
2017-09-26 18:54 ` Siddhesh Poyarekar [this message]
2017-09-26 20:07 ` Carlos O'Donell
2017-09-26 21:17 ` Siddhesh Poyarekar
-- strict thread matches above, loose matches on Subject: below --
2017-07-19 21:34 Alexey Makhalov
2017-07-20 1:43 ` Carlos O'Donell
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