* [PATCH v3] elf: Use C11 atomics on _dl_mcount
@ 2022-09-20 19:04 Adhemerval Zanella
2022-09-20 22:59 ` Wilco Dijkstra
0 siblings, 1 reply; 3+ messages in thread
From: Adhemerval Zanella @ 2022-09-20 19:04 UTC (permalink / raw)
To: libc-alpha, Wilco Dijkstra
All atomic operation are counters, so relaxed MO should be suffice.
Checked on x86_64-linux-gnu.
---
elf/dl-profile.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/elf/dl-profile.c b/elf/dl-profile.c
index ec57e3a965..c5ac9b5a3e 100644
--- a/elf/dl-profile.c
+++ b/elf/dl-profile.c
@@ -548,7 +548,7 @@ _dl_mcount (ElfW(Addr) frompc, ElfW(Addr) selfpc)
size_t newfromidx;
to_index = (data[narcs].self_pc
/ (HASHFRACTION * sizeof (*tos)));
- newfromidx = catomic_exchange_and_add (&fromidx, 1) + 1;
+ newfromidx = atomic_fetch_add_relaxed (&fromidx, 1) + 1;
froms[newfromidx].here = &data[narcs];
froms[newfromidx].link = tos[to_index];
tos[to_index] = newfromidx;
@@ -558,14 +558,14 @@ _dl_mcount (ElfW(Addr) frompc, ElfW(Addr) selfpc)
/* If we still have no entry stop searching and insert. */
if (*topcindex == 0)
{
- unsigned int newarc = catomic_exchange_and_add (narcsp, 1);
+ unsigned int newarc = atomic_fetch_add_relaxed (narcsp, 1) + 1;
/* In rare cases it could happen that all entries in FROMS are
occupied. So we cannot count this anymore. */
if (newarc >= fromlimit)
goto done;
- *topcindex = catomic_exchange_and_add (&fromidx, 1) + 1;
+ *topcindex = atomic_fetch_add_relaxed (&fromidx, 1) + 1;
fromp = &froms[*topcindex];
fromp->here = &data[newarc];
@@ -573,7 +573,7 @@ _dl_mcount (ElfW(Addr) frompc, ElfW(Addr) selfpc)
data[newarc].self_pc = selfpc;
data[newarc].count = 0;
fromp->link = 0;
- catomic_increment (&narcs);
+ atomic_fetch_add_relaxed (&narcs, 1);
break;
}
@@ -586,7 +586,7 @@ _dl_mcount (ElfW(Addr) frompc, ElfW(Addr) selfpc)
}
/* Increment the counter. */
- catomic_increment (&fromp->here->count);
+ atomic_fetch_add_relaxed (&fromp->here->count, 1);
done:
;
--
2.34.1
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v3] elf: Use C11 atomics on _dl_mcount
2022-09-20 19:04 [PATCH v3] elf: Use C11 atomics on _dl_mcount Adhemerval Zanella
@ 2022-09-20 22:59 ` Wilco Dijkstra
2022-09-21 14:01 ` Adhemerval Zanella Netto
0 siblings, 1 reply; 3+ messages in thread
From: Wilco Dijkstra @ 2022-09-20 22:59 UTC (permalink / raw)
To: Adhemerval Zanella, libc-alpha
Hi Adhemerval,
@@ -558,14 +558,14 @@ _dl_mcount (ElfW(Addr) frompc, ElfW(Addr) selfpc)
/* If we still have no entry stop searching and insert. */
if (*topcindex == 0)
{
- unsigned int newarc = catomic_exchange_and_add (narcsp, 1);
+ unsigned int newarc = atomic_fetch_add_relaxed (narcsp, 1) + 1;
This adds a spurious + 1. Other than that it looks good to me.
Reviewed-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
Cheers,
Wilco
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v3] elf: Use C11 atomics on _dl_mcount
2022-09-20 22:59 ` Wilco Dijkstra
@ 2022-09-21 14:01 ` Adhemerval Zanella Netto
0 siblings, 0 replies; 3+ messages in thread
From: Adhemerval Zanella Netto @ 2022-09-21 14:01 UTC (permalink / raw)
To: Wilco Dijkstra, libc-alpha
On 20/09/22 19:59, Wilco Dijkstra wrote:
> Hi Adhemerval,
>
>
> @@ -558,14 +558,14 @@ _dl_mcount (ElfW(Addr) frompc, ElfW(Addr) selfpc)
> /* If we still have no entry stop searching and insert. */
> if (*topcindex == 0)
> {
> - unsigned int newarc = catomic_exchange_and_add (narcsp, 1);
> + unsigned int newarc = atomic_fetch_add_relaxed (narcsp, 1) + 1;
>
> This adds a spurious + 1. Other than that it looks good to me.
Thanks, I have removed it.
>
> Reviewed-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
>
> Cheers,
> Wilco
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-09-20 19:04 [PATCH v3] elf: Use C11 atomics on _dl_mcount Adhemerval Zanella
2022-09-20 22:59 ` Wilco Dijkstra
2022-09-21 14:01 ` Adhemerval Zanella Netto
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