[PATCH mpam mpam/snapshot+extras/v6.18-rc1 v2 1/3] fs/resctrl: Fix incorrect PID parsing after IOMMU group token

[Zeng Heng]

When the tasks interface receives an "iommu_group:id" configuration,
the original code fails to skip the PID parsing logic after processing
the IOMMU group. This causes the same token to be incorrectly passed
to kstrtoint() as a PID, resulting in -EINVAL.

Restructure the conditional logic to use explicit if-else branches,
ensuring that IOMMU group tokens are processed by rdtgroup_move_iommu()
and then skipped.

This fix also enables proper handling of mixed configurations with
multiple consecutive iommu_group:id and pid entries (e.g.,
echo "iommu_group:1,1234,iommu_group:2,5678" > tasks).

Fixes: 98b622c413ee ("fs/resctrl: Add support for assigning iommu_groups to resctrl groups")
Signed-off-by: Zeng Heng <zengheng4@xxxxxxxxxx>
---
 fs/resctrl/rdtgroup.c | 39 ++++++++++++++++++++++++---------------
 1 file changed, 24 insertions(+), 15 deletions(-)

diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 5381233adceb..1810ace9538f 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -848,24 +848,33 @@ static ssize_t rdtgroup_tasks_write(struct kernfs_open_file *of,
 		pid_str = strim(strsep(&buf, ","));
 
 		is_iommu = string_is_iommu_group(pid_str, &iommu_group_id);
-		if (is_iommu)
+		if (is_iommu) {
 			ret = rdtgroup_move_iommu(iommu_group_id, rdtgrp, of);
-		else if (kstrtoint(pid_str, 0, &pid)) {
-			rdt_last_cmd_printf("Task list parsing error pid %s\n", pid_str);
-			ret = -EINVAL;
-			break;
-		}
+			if (ret) {
+				rdt_last_cmd_printf("Error while processing iommu_group %d\n",
+						     iommu_group_id);
+				break;
+			}
+		} else {
+			if (kstrtoint(pid_str, 0, &pid)) {
+				rdt_last_cmd_printf("Task list parsing error pid %s\n",
+						     pid_str);
+				ret = -EINVAL;
+				break;
+			}
 
-		if (pid < 0) {
-			rdt_last_cmd_printf("Invalid pid %d\n", pid);
-			ret = -EINVAL;
-			break;
-		}
+			if (pid < 0) {
+				rdt_last_cmd_printf("Invalid pid %d\n", pid);
+				ret = -EINVAL;
+				break;
+			}
 
-		ret = rdtgroup_move_task(pid, rdtgrp, of);
-		if (ret) {
-			rdt_last_cmd_printf("Error while processing task %d\n", pid);
-			break;
+			ret = rdtgroup_move_task(pid, rdtgrp, of);
+			if (ret) {
+				rdt_last_cmd_printf("Error while processing task %d\n",
+						     pid);
+				break;
+			}
 		}
 	}
 
-- 
2.25.1