[PATCH 5.19 055/155] platform/mellanox: mlxreg-lc: Fix locking issue

Greg Kroah-Hartman
2022-09-06T14:06:20Z

From: Vadim Pasternak <vadimp@nvidia.com>

[ Upstream commit 1e092b7faa6b507125b69c92a51bb22c2d549d37 ]

Fix locking issues:
- mlxreg_lc_state_update() takes a lock when set or clear
"MLXREG_LC_POWERED".
- All the devices can be deleted before MLXREG_LC_POWERED flag is cleared.

To fix it:
- Add lock() / unlock() at the beginning / end of
mlxreg_lc_event_handler() and remove locking from
mlxreg_lc_power_on_off() and mlxreg_lc_enable_disable()
- Add locked version of mlxreg_lc_state_update() -
mlxreg_lc_state_update_locked() for using outside
mlxreg_lc_event_handler().

(2) Remove redundant NULL check for of if 'data->notifier'.

Fixes: 62f9529b8d5c87b ("platform/mellanox: mlxreg-lc: Add initial support for Nvidia line card devices")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
Link: https://lore.kernel.org/r/20220823201937.46855-3-vadimp@nvidia.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/platform/mellanox/mlxreg-lc.c | 37 ++++++++++++++++++---------
1 file changed, 25 insertions(+), 12 deletions(-)

diff --git a/drivers/platform/mellanox/mlxreg-lc.c b/drivers/platform/mellanox/mlxreg-lc.c
index 9a1bfcd24317d..e578c7bc060bb 100644
--- a/drivers/platform/mellanox/mlxreg-lc.c
+++ b/drivers/platform/mellanox/mlxreg-lc.c
@@ -460,8 +460,6 @@ static int mlxreg_lc_power_on_off(struct mlxreg_lc *mlxreg_lc, u8 action)
u32 regval;
int err;

- mutex_lock(&mlxreg_lc->lock);
-
err = regmap_read(mlxreg_lc->par_regmap, mlxreg_lc->data->reg_pwr, &regval);
if (err)
goto regmap_read_fail;
@@ -474,7 +472,6 @@ static int mlxreg_lc_power_on_off(struct mlxreg_lc *mlxreg_lc, u8 action)
err = regmap_write(mlxreg_lc->par_regmap, mlxreg_lc->data->reg_pwr, regval);

regmap_read_fail:
- mutex_unlock(&mlxreg_lc->lock);
return err;
}

@@ -491,8 +488,6 @@ static int mlxreg_lc_enable_disable(struct mlxreg_lc *mlxreg_lc, bool action)
* line card which is already has been enabled. Disabling does not affect the disabled line
* card.
*/
- mutex_lock(&mlxreg_lc->lock);
-
err = regmap_read(mlxreg_lc->par_regmap, mlxreg_lc->data->reg_ena, &regval);
if (err)
goto regmap_read_fail;
@@ -505,7 +500,6 @@ static int mlxreg_lc_enable_disable(struct mlxreg_lc *mlxreg_lc, bool action)
err = regmap_write(mlxreg_lc->par_regmap, mlxreg_lc->data->reg_ena, regval);

regmap_read_fail:
- mutex_unlock(&mlxreg_lc->lock);
return err;
}

@@ -537,6 +531,15 @@ mlxreg_lc_sn4800_c16_config_init(struct mlxreg_lc *mlxreg_lc, void *regmap,

static void
mlxreg_lc_state_update(struct mlxreg_lc *mlxreg_lc, enum mlxreg_lc_state state, u8 action)
+{
+ if (action)
+ mlxreg_lc->state |= state;
+ else
+ mlxreg_lc->state &= ~state;
+}
+
+static void
+mlxreg_lc_state_update_locked(struct mlxreg_lc *mlxreg_lc, enum mlxreg_lc_state state, u8 action)
{
mutex_lock(&mlxreg_lc->lock);

@@ -560,8 +563,11 @@ static int mlxreg_lc_event_handler(void *handle, enum mlxreg_hotplug_kind kind,
dev_info(mlxreg_lc->dev, "linecard#%d state %d event kind %d action %d\n",
mlxreg_lc->data->slot, mlxreg_lc->state, kind, action);

- if (!(mlxreg_lc->state & MLXREG_LC_INITIALIZED))
+ mutex_lock(&mlxreg_lc->lock);
+ if (!(mlxreg_lc->state & MLXREG_LC_INITIALIZED)) {
+ mutex_unlock(&mlxreg_lc->lock);
return 0;
+ }

switch (kind) {
case MLXREG_HOTPLUG_LC_SYNCED:
@@ -574,7 +580,7 @@ static int mlxreg_lc_event_handler(void *handle, enum mlxreg_hotplug_kind kind,
if (!(mlxreg_lc->state & MLXREG_LC_POWERED) && action) {
err = mlxreg_lc_power_on_off(mlxreg_lc, 1);
if (err)
- return err;
+ goto mlxreg_lc_power_on_off_fail;
}
/* In case line card is configured - enable it. */
if (mlxreg_lc->state & MLXREG_LC_CONFIGURED && action)
@@ -588,12 +594,13 @@ static int mlxreg_lc_event_handler(void *handle, enum mlxreg_hotplug_kind kind,
/* In case line card is configured - enable it. */
if (mlxreg_lc->state & MLXREG_LC_CONFIGURED)
err = mlxreg_lc_enable_disable(mlxreg_lc, 1);
+ mutex_unlock(&mlxreg_lc->lock);
return err;
}
err = mlxreg_lc_create_static_devices(mlxreg_lc, mlxreg_lc->main_devs,
mlxreg_lc->main_devs_num);
if (err)
- return err;
+ goto mlxreg_lc_create_static_devices_fail;

/* In case line card is already in ready state - enable it. */
if (mlxreg_lc->state & MLXREG_LC_CONFIGURED)
@@ -620,6 +627,10 @@ static int mlxreg_lc_event_handler(void *handle, enum mlxreg_hotplug_kind kind,
break;
}

+mlxreg_lc_power_on_off_fail:
+mlxreg_lc_create_static_devices_fail:
+ mutex_unlock(&mlxreg_lc->lock);
+
return err;
}

@@ -665,7 +676,7 @@ static int mlxreg_lc_completion_notify(void *handle, struct i2c_adapter *parent,
if (err)
goto mlxreg_lc_create_static_devices_failed;

- mlxreg_lc_state_update(mlxreg_lc, MLXREG_LC_POWERED, 1);
+ mlxreg_lc_state_update_locked(mlxreg_lc, MLXREG_LC_POWERED, 1);
}

/* Verify if line card is synchronized. */
@@ -676,7 +687,7 @@ static int mlxreg_lc_completion_notify(void *handle, struct i2c_adapter *parent,
/* Power on line card if necessary. */
if (regval & mlxreg_lc->data->mask) {
mlxreg_lc->state |= MLXREG_LC_SYNCED;
- mlxreg_lc_state_update(mlxreg_lc, MLXREG_LC_SYNCED, 1);
+ mlxreg_lc_state_update_locked(mlxreg_lc, MLXREG_LC_SYNCED, 1);
if (mlxreg_lc->state & ~MLXREG_LC_POWERED) {
err = mlxreg_lc_power_on_off(mlxreg_lc, 1);
if (err)
@@ -684,7 +695,7 @@ static int mlxreg_lc_completion_notify(void *handle, struct i2c_adapter *parent,
}
}

- mlxreg_lc_state_update(mlxreg_lc, MLXREG_LC_INITIALIZED, 1);
+ mlxreg_lc_state_update_locked(mlxreg_lc, MLXREG_LC_INITIALIZED, 1);

return 0;

@@ -904,6 +915,8 @@ static int mlxreg_lc_remove(struct platform_device *pdev)
struct mlxreg_core_data *data = dev_get_platdata(&pdev->dev);
struct mlxreg_lc *mlxreg_lc = platform_get_drvdata(pdev);

+ mlxreg_lc_state_update_locked(mlxreg_lc, MLXREG_LC_INITIALIZED, 0);
+
/*
* Probing and removing are invoked by hotplug events raised upon line card insertion and
* removing. If probing procedure fails all data is cleared. However, hotplug event still
--
2.35.1