[Xen-devel] [PATCH] Correctly return success from IOCTL_PRIVCMD_MMAPBATCH

[Mats Petersson <mats.petersson@xxxxxxxxxx>]

This is a regression introduced by ceb90fa0 (xen/privcmd: add
PRIVCMD_MMAPBATCH_V2 ioctl).  It broke xentrace as it used
xc_map_foreign() instead of xc_map_foreign_bulk().

Most code-paths prefer the MMAPBATCH_V2, so this wasn't very obvious
that it broke. The return value is set early on to -EINVAL, and if all
goes well, the "set top bits of the MFN's" never gets called, so the
return value is still EINVAL when the function gets to the end, causing
the caller to think it went wrong (which it didn't!)

Signed off by: Mats Petersson <mats.petersson@xxxxxxxxxx>
Acked-by: David Vrabel <david.vrabel@xxxxxxxxxx>

---
 drivers/xen/privcmd.c |   16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
index 8adb9cc..24aec2f 100644
--- a/drivers/xen/privcmd.c
+++ b/drivers/xen/privcmd.c
@@ -383,12 +383,16 @@ static long privcmd_ioctl_mmap_batch(void __user *udata, 
int version)
 
        up_write(&mm->mmap_sem);
 
-       if (state.global_error && (version == 1)) {
-               /* Write back errors in second pass. */
-               state.user_mfn = (xen_pfn_t *)m.arr;
-               state.err      = err_array;
-               ret = traverse_pages(m.num, sizeof(xen_pfn_t),
-                                    &pagelist, mmap_return_errors_v1, &state);
+       if (version == 1) {
+               if (state.global_error) {
+                       /* Write back errors in second pass. */
+                       state.user_mfn = (xen_pfn_t *)m.arr;
+                       state.err      = err_array;
+                       ret = traverse_pages(m.num, sizeof(xen_pfn_t),
+                                            &pagelist, mmap_return_errors_v1, 
&state);
+               } else
+                       ret = 0;
+
        } else if (version == 2) {
                ret = __copy_to_user(m.err, err_array, m.num * sizeof(int));
                if (ret)
-- 
1.7.9.5


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