platform/mellanox: mlxreg-lc: Fix locking issue

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>

diff --git a/drivers/platform/mellanox/mlxreg-lc.c b/drivers/platform/mellanox/mlxreg-lc.c
index 9a1bfcd..e578c7b 100644 (file)
--- 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;
 }
 
@@ -538,6 +532,15 @@ 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);
 
        if (action)
@@ -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