From: Arnd Bergmann <arnd@arndb.de>
To: Saeed Mahameed <saeedm@mellanox.com>,
Leon Romanovsky <leon@kernel.org>,
"David S. Miller" <davem@davemloft.net>
Cc: Arnd Bergmann <arnd@arndb.de>,
Adhemerval Zanella <adhemerval.zanella@linaro.org>,
Tariq Toukan <tariqt@mellanox.com>,
Shay Agroskin <shayag@mellanox.com>,
Eran Ben Elisha <eranbe@mellanox.com>,
Maxim Mikityanskiy <maximmi@mellanox.com>,
Aya Levin <ayal@mellanox.com>, Moshe Shemesh <moshe@mellanox.com>,
netdev@vger.kernel.org, linux-rdma@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [PATCH] mlx5: work around high stack usage with gcc
Date: Sat, 4 Jan 2020 22:51:44 +0100 [thread overview]
Message-ID: <20200104215156.689245-1-arnd@arndb.de> (raw)
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 <adhemerval.zanella@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
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 9f09253f9f46..a05158472ed1 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_stats.c
@@ -297,6 +297,9 @@ static void mlx5e_grp_sw_update_stats(struct mlx5e_priv *priv)
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();
}
}
}
--
2.20.0
next reply other threads:[~2020-01-04 21:52 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-04 21:51 Arnd Bergmann [this message]
2020-01-06 21:34 ` [PATCH] mlx5: work around high stack usage with gcc David Miller
2020-01-06 21:59 ` Saeed Mahameed
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