[PATCH 6.1 178/473] net/mlx5: Add a timeout to acquire the command queue semaphore

Greg Kroah-Hartman
2024-06-06T14:15:27Z

From: Akiva Goldberger <agoldberger@nvidia.com>

[ Upstream commit 485d65e1357123a697c591a5aeb773994b247ad7 ]

Prevent forced completion handling on an entry that has not yet been
assigned an index, causing an out of bounds access on idx = -22.
Instead of waiting indefinitely for the sem, blocking flow now waits for
index to be allocated or a sem acquisition timeout before beginning the
timer for FW completion.

Kernel log example:
mlx5_core 0000:06:00.0: wait_func_handle_exec_timeout:1128:(pid 185911): cmd[-22]: CREATE_UCTX(0xa04) No done completion

Fixes: 8e715cd613a1 ("net/mlx5: Set command entry semaphore up once got index free")
Signed-off-by: Akiva Goldberger <agoldberger@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://lore.kernel.org/r/20240509112951.590184-5-tariqt@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/mellanox/mlx5/core/cmd.c | 41 +++++++++++++++----
include/linux/mlx5/driver.h | 1 +
2 files changed, 33 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/cmd.c b/drivers/net/ethernet/mellanox/mlx5/core/cmd.c
index ac6a0785b10d8..946923b9404fc 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/cmd.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/cmd.c
@@ -964,19 +964,32 @@ static void cmd_work_handler(struct work_struct *work)
bool poll_cmd = ent->polling;
struct mlx5_cmd_layout *lay;
struct mlx5_core_dev *dev;
- unsigned long cb_timeout;
- struct semaphore *sem;
+ unsigned long timeout;
unsigned long flags;
int alloc_ret;
int cmd_mode;

+ complete(&ent->handling);
+
dev = container_of(cmd, struct mlx5_core_dev, cmd);
- cb_timeout = msecs_to_jiffies(mlx5_tout_ms(dev, CMD));
+ timeout = msecs_to_jiffies(mlx5_tout_ms(dev, CMD));

- complete(&ent->handling);
- sem = ent->page_queue ? &cmd->vars.pages_sem : &cmd->vars.sem;
- down(sem);
if (!ent->page_queue) {
+ if (down_timeout(&cmd->vars.sem, timeout)) {
+ mlx5_core_warn(dev, "%s(0x%x) timed out while waiting for a slot.\n",
+ mlx5_command_str(ent->op), ent->op);
+ if (ent->callback) {
+ ent->callback(-EBUSY, ent->context);
+ mlx5_free_cmd_msg(dev, ent->out);
+ free_msg(dev, ent->in);
+ cmd_ent_put(ent);
+ } else {
+ ent->ret = -EBUSY;
+ complete(&ent->done);
+ }
+ complete(&ent->slotted);
+ return;
+ }
alloc_ret = cmd_alloc_index(cmd, ent);
if (alloc_ret < 0) {
mlx5_core_err_rl(dev, "failed to allocate command entry\n");
@@ -989,10 +1002,11 @@ static void cmd_work_handler(struct work_struct *work)
ent->ret = -EAGAIN;
complete(&ent->done);
}
- up(sem);
+ up(&cmd->vars.sem);
return;
}
} else {
+ down(&cmd->vars.pages_sem);
ent->idx = cmd->vars.max_reg_cmds;
spin_lock_irqsave(&cmd->alloc_lock, flags);
clear_bit(ent->idx, &cmd->vars.bitmask);
@@ -1000,6 +1014,8 @@ static void cmd_work_handler(struct work_struct *work)
spin_unlock_irqrestore(&cmd->alloc_lock, flags);
}

+ complete(&ent->slotted);
+
lay = get_inst(cmd, ent->idx);
ent->lay = lay;
memset(lay, 0, sizeof(*lay));
@@ -1018,7 +1034,7 @@ static void cmd_work_handler(struct work_struct *work)
ent->ts1 = ktime_get_ns();
cmd_mode = cmd->mode;

- if (ent->callback && schedule_delayed_work(&ent->cb_timeout_work, cb_timeout))
+ if (ent->callback && schedule_delayed_work(&ent->cb_timeout_work, timeout))
cmd_ent_get(ent);
set_bit(MLX5_CMD_ENT_STATE_PENDING_COMP, &ent->state);

@@ -1138,6 +1154,9 @@ static int wait_func(struct mlx5_core_dev *dev, struct mlx5_cmd_work_ent *ent)
ent->ret = -ECANCELED;
goto out_err;
}
+
+ wait_for_completion(&ent->slotted);
+
if (cmd->mode == CMD_MODE_POLLING || ent->polling)
wait_for_completion(&ent->done);
else if (!wait_for_completion_timeout(&ent->done, timeout))
@@ -1152,6 +1171,9 @@ static int wait_func(struct mlx5_core_dev *dev, struct mlx5_cmd_work_ent *ent)
} else if (err == -ECANCELED) {
mlx5_core_warn(dev, "%s(0x%x) canceled on out of queue timeout.\n",
mlx5_command_str(ent->op), ent->op);
+ } else if (err == -EBUSY) {
+ mlx5_core_warn(dev, "%s(0x%x) timeout while waiting for command semaphore.\n",
+ mlx5_command_str(ent->op), ent->op);
}
mlx5_core_dbg(dev, "err %d, delivery status %s(%d)\n",
err, deliv_status_to_str(ent->status), ent->status);
@@ -1203,6 +1225,7 @@ static int mlx5_cmd_invoke(struct mlx5_core_dev *dev, struct mlx5_cmd_msg *in,
ent->polling = force_polling;

init_completion(&ent->handling);
+ init_completion(&ent->slotted);
if (!callback)
init_completion(&ent->done);

@@ -1220,7 +1243,7 @@ static int mlx5_cmd_invoke(struct mlx5_core_dev *dev, struct mlx5_cmd_msg *in,
return 0; /* mlx5_cmd_comp_handler() will put(ent) */

err = wait_func(dev, ent);
- if (err == -ETIMEDOUT || err == -ECANCELED)
+ if (err == -ETIMEDOUT || err == -ECANCELED || err == -EBUSY)
goto out_free;

ds = ent->ts2 - ent->ts1;
diff --git a/include/linux/mlx5/driver.h b/include/linux/mlx5/driver.h
index 93ec34a94b724..1cae12185cf04 100644
--- a/include/linux/mlx5/driver.h
+++ b/include/linux/mlx5/driver.h
@@ -850,6 +850,7 @@ struct mlx5_cmd_work_ent {
void *context;
int idx;
struct completion handling;
+ struct completion slotted;
struct completion done;
struct mlx5_cmd *cmd;
struct work_struct work;
--
2.43.0