clean up and guard against negative amm_inventory_limit

Author: moosecat2

programs/drift/src/instructions/lp_admin.rs

@@ -998,6 +998,10 @@ pub fn handle_override_amm_cache_info<'c: 'info, 'info>(
     }
 
     if let Some(amm_inventory_limit) = override_params.amm_inventory_limit {
+        if amm_inventory_limit < 0 {
+            msg!("amm_inventory_limit must be non-negative");
+            return Err(ErrorCode::DefaultError.into());
+        }
         cache_entry.amm_inventory_limit = amm_inventory_limit;
     }
 

programs/drift/src/instructions/lp_pool.rs

@@ -131,13 +131,17 @@ pub fn handle_update_constituent_target_base<'c: 'info, 'info>(
         }
 
         amm_inventories.push(AmmInventoryAndPrices {
-            inventory: cache_info
-                .position
-                .safe_mul(cache_info.amm_position_scalar as i64)?
-                .safe_div(100)?
-                .abs()
-                .min(cache_info.amm_inventory_limit)
-                .safe_mul(cache_info.position.signum())?,
+            inventory: {
+                let scaled_position = cache_info
+                    .position
+                    .safe_mul(cache_info.amm_position_scalar as i64)?
+                    .safe_div(100)?;
+
+                scaled_position.clamp(
+                    -cache_info.amm_inventory_limit,
+                    cache_info.amm_inventory_limit,
+                )
+            },
             price: cache_info.oracle_price,
         });
     }