[PATCH 5.4 115/320] net/mlx5: Set command entry semaphore up once got index free

Greg Kroah-Hartman
2022-01-24T20:10:55Z

From: Moshe Shemesh <moshe@nvidia.com>

[ Upstream commit 8e715cd613a1e872b9d918e912d90b399785761a ]

Avoid a race where command work handler may fail to allocate command
entry index, by holding the command semaphore down till command entry
index is being freed.

Fixes: 410bd754cd73 ("net/mlx5: Add retry mechanism to the command entry index allocation")
Signed-off-by: Moshe Shemesh <moshe@nvidia.com>
Reviewed-by: Eran Ben Elisha <eranbe@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/mellanox/mlx5/core/cmd.c | 15 ++++++---------
1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/cmd.c b/drivers/net/ethernet/mellanox/mlx5/core/cmd.c
index bf091a6c0cd2d..cedb102ce8d2f 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/cmd.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/cmd.c
@@ -147,8 +147,12 @@ static void cmd_ent_put(struct mlx5_cmd_work_ent *ent)
if (!refcount_dec_and_test(&ent->refcnt))
return;

- if (ent->idx >= 0)
- cmd_free_index(ent->cmd, ent->idx);
+ if (ent->idx >= 0) {
+ struct mlx5_cmd *cmd = ent->cmd;
+
+ cmd_free_index(cmd, ent->idx);
+ up(ent->page_queue ? &cmd->pages_sem : &cmd->sem);
+ }

cmd_free_ent(ent);
}
@@ -1577,8 +1581,6 @@ static void mlx5_cmd_comp_handler(struct mlx5_core_dev *dev, u64 vec, bool force
vector = vec & 0xffffffff;
for (i = 0; i < (1 << cmd->log_sz); i++) {
if (test_bit(i, &vector)) {
- struct semaphore *sem;
-
ent = cmd->ent_arr[i];

/* if we already completed the command, ignore it */
@@ -1601,10 +1603,6 @@ static void mlx5_cmd_comp_handler(struct mlx5_core_dev *dev, u64 vec, bool force
dev->state == MLX5_DEVICE_STATE_INTERNAL_ERROR)
cmd_ent_put(ent);

- if (ent->page_queue)
- sem = &cmd->pages_sem;
- else
- sem = &cmd->sem;
ent->ts2 = ktime_get_ns();
memcpy(ent->out->first.data, ent->lay->out, sizeof(ent->lay->out));
dump_command(dev, ent, 0);
@@ -1658,7 +1656,6 @@ static void mlx5_cmd_comp_handler(struct mlx5_core_dev *dev, u64 vec, bool force
*/
complete(&ent->done);
}
- up(sem);
}
}
}
--
2.34.1