From 32bd5c04ec418a69b6e9701faa84ef0a7abb2745 Mon Sep 17 00:00:00 2001 From: Alaa Hleihel Date: Tue, 12 May 2020 10:53:35 -0400 Subject: [PATCH 129/312] [netdrv] mlx5: work around high stack usage with gcc Message-id: <20200512105530.4207-10-ahleihel@redhat.com> Patchwork-id: 306881 Patchwork-instance: patchwork O-Subject: [RHEL8.3 BZ 1789382 009/124] mlx5: work around high stack usage with gcc Bugzilla: 1789382 RH-Acked-by: Tony Camuso RH-Acked-by: Kamal Heib RH-Acked-by: Jarod Wilson Bugzilla: http://bugzilla.redhat.com/1789382 Upstream: v5.6-rc1 commit 42ae1a5c76691928ed217c7e40269db27f5225e9 Author: Arnd Bergmann Date: Sat Jan 4 22:51:44 2020 +0100 mlx5: work around high stack usage with gcc In some configurations, gcc tries too hard to optimize this code: drivers/net/ethernet/mellanox/mlx5/core/en_stats.c: In function 'mlx5e_grp_sw_update_stats': drivers/net/ethernet/mellanox/mlx5/core/en_stats.c:302:1: error: the frame size of 1336 bytes is larger than 1024 bytes [-Werror=frame-larger-than=] As was stated in the bug report, the reason is that gcc runs into a corner case in the register allocator that is rather hard to fix in a good way. As there is an easy way to work around it, just add a comment and the barrier that stops gcc from trying to overoptimize the function. Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92657 Cc: Adhemerval Zanella Signed-off-by: Arnd Bergmann Signed-off-by: Saeed Mahameed Signed-off-by: Alaa Hleihel Signed-off-by: Frantisek Hrbata --- drivers/net/ethernet/mellanox/mlx5/core/en_stats.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c b/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c index 23587f55fad7..30b216d9284c 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c @@ -349,6 +349,9 @@ static MLX5E_DECLARE_STATS_GRP_OP_UPDATE_STATS(sw) s->tx_tls_drop_bypass_req += sq_stats->tls_drop_bypass_req; #endif s->tx_cqes += sq_stats->cqes; + + /* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92657 */ + barrier(); } } } -- 2.13.6