[xen staging] libxc/PM: Retry get_pxstat if data is incomplete

[patchbot@xxxxxxx]

commit 1ff7f87e8f4ffff97901126927549ae7b7a7340d
Author:     Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
AuthorDate: Wed Jun 11 11:07:00 2025 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Jun 11 11:07:00 2025 +0200

    libxc/PM: Retry get_pxstat if data is incomplete
    
    If the total returned by Xen is more than the number of elements
    allocated, it means that the buffer was too small and so the data is
    incomplete. Retry to get all the data.
    
    Signed-off-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
    Reviewed-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
---
 tools/misc/xenpm.c | 49 +++++++++++++++++++++++++++++++------------------
 1 file changed, 31 insertions(+), 18 deletions(-)

diff --git a/tools/misc/xenpm.c b/tools/misc/xenpm.c
index de319329e6..d5387f5f06 100644
--- a/tools/misc/xenpm.c
+++ b/tools/misc/xenpm.c
@@ -312,29 +312,42 @@ static int get_pxstat_by_cpuid(xc_interface *xc_handle, 
int cpuid, struct xc_px_
     int ret = 0;
     int max_px_num = 0;
 
-    ret = xc_pm_get_max_px(xc_handle, cpuid, &max_px_num);
-    if ( ret )
-        return -errno;
-
     if ( !pxstat)
         return -EINVAL;
 
-    pxstat->total = max_px_num;
-    pxstat->trans_pt = malloc(max_px_num * max_px_num *
-                              sizeof(uint64_t));
-    if ( !pxstat->trans_pt )
-        return -ENOMEM;
-    pxstat->pt = malloc(max_px_num * sizeof(struct xc_px_val));
-    if ( !pxstat->pt )
+    for ( ; ; )
     {
-        free(pxstat->trans_pt);
-        return -ENOMEM;
-    }
+        ret = xc_pm_get_max_px(xc_handle, cpuid, &max_px_num);
+        if ( ret )
+            return -errno;
 
-    ret = xc_pm_get_pxstat(xc_handle, cpuid, pxstat);
-    if( ret )
-    {
-        ret = -errno;
+        pxstat->total = max_px_num;
+        pxstat->trans_pt = malloc(max_px_num * max_px_num *
+                                  sizeof(uint64_t));
+        if ( !pxstat->trans_pt )
+            return -ENOMEM;
+        pxstat->pt = malloc(max_px_num * sizeof(struct xc_px_val));
+        if ( !pxstat->pt )
+        {
+            free(pxstat->trans_pt);
+            return -ENOMEM;
+        }
+
+        ret = xc_pm_get_pxstat(xc_handle, cpuid, pxstat);
+        if ( ret )
+        {
+            ret = -errno;
+            free(pxstat->trans_pt);
+            free(pxstat->pt);
+            pxstat->trans_pt = NULL;
+            pxstat->pt = NULL;
+            break;
+        }
+
+        if ( pxstat->total <= max_px_num )
+            break;
+
+        /* get_max_px changed under our feet so the data is incomplete. */
         free(pxstat->trans_pt);
         free(pxstat->pt);
         pxstat->trans_pt = NULL;
--
generated by git-patchbot for /home/xen/git/xen.git#staging