[xen stable-4.19] tools/lsevtchn: Use errno macro to handle hypercall error cases

[patchbot@xxxxxxx]

commit e0e84771b61ed985809d105d8f116d4c520542b0
Author:     Matthew Barnes <matthew.barnes@xxxxxxxxx>
AuthorDate: Thu Aug 8 13:47:30 2024 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Aug 8 13:47:30 2024 +0200

    tools/lsevtchn: Use errno macro to handle hypercall error cases
    
    Currently, lsevtchn aborts its event channel enumeration when it hits
    an event channel that is owned by Xen.
    
    lsevtchn does not distinguish between different hypercall errors, which
    results in lsevtchn missing potential relevant event channels with
    higher port numbers.
    
    Use the errno macro to distinguish between hypercall errors, and
    continue event channel enumeration if the hypercall error is not
    critical to enumeration.
    
    Signed-off-by: Matthew Barnes <matthew.barnes@xxxxxxxxx>
    Reviewed-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
    master commit: e92a453c8db8bba62d6be3006079e2b9990c3978
    master date: 2024-08-02 08:43:57 +0200
---
 tools/xcutils/lsevtchn.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/tools/xcutils/lsevtchn.c b/tools/xcutils/lsevtchn.c
index d1710613dd..30c8d847b8 100644
--- a/tools/xcutils/lsevtchn.c
+++ b/tools/xcutils/lsevtchn.c
@@ -3,6 +3,7 @@
 #include <stdint.h>
 #include <string.h>
 #include <stdio.h>
+#include <errno.h>
 
 #include <xenctrl.h>
 
@@ -24,7 +25,23 @@ int main(int argc, char **argv)
         status.port = port;
         rc = xc_evtchn_status(xch, &status);
         if ( rc < 0 )
-            break;
+        {
+            switch ( errno )
+            {
+            case EACCES: /* Xen-owned evtchn */
+                continue;
+
+            case EINVAL: /* Port enumeration has ended */
+                rc = 0;
+                break;
+
+            default:
+                perror("xc_evtchn_status");
+                rc = 1;
+                break;
+            }
+            goto out;
+        }
 
         if ( status.status == EVTCHNSTAT_closed )
             continue;
@@ -58,7 +75,8 @@ int main(int argc, char **argv)
         printf("\n");
     }
 
+ out:
     xc_interface_close(xch);
 
-    return 0;
+    return rc;
 }
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.19