[Qemu-devel] [5267] Swap only altered elements of the grouplist in getgroups() ( Kirill Shutemov).

[Andrzej Zaborowski]

Revision: 5267
          http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=5267
Author:   balrog
Date:     2008-09-20 02:12:08 +0000 (Sat, 20 Sep 2008)

Log Message:
-----------
Swap only altered elements of the grouplist in getgroups() (Kirill Shutemov).

getgroups() returns the number of supplementary group IDs, so it's
unnessary to swap the entire array.  It can dramatically speed up
the syscall: on recent Linux kernels NGROUPS_MAX=65536.

Signed-off-by: Kirill A. Shutemov <address@hidden>

Modified Paths:
--------------
    trunk/linux-user/syscall.c

Modified: trunk/linux-user/syscall.c
===================================================================
--- trunk/linux-user/syscall.c  2008-09-20 02:08:13 UTC (rev 5266)
+++ trunk/linux-user/syscall.c  2008-09-20 02:12:08 UTC (rev 5267)
@@ -5253,7 +5253,7 @@
                 target_grouplist = lock_user(VERIFY_WRITE, arg2, gidsetsize * 
2, 0);
                 if (!target_grouplist)
                     goto efault;
-                for(i = 0;i < gidsetsize; i++)
+                for(i = 0;i < ret; i++)
                     target_grouplist[i] = tswap16(grouplist[i]);
                 unlock_user(target_grouplist, arg2, gidsetsize * 2);
             }
@@ -5407,7 +5407,7 @@
                     ret = -TARGET_EFAULT;
                     goto fail;
                 }
-                for(i = 0;i < gidsetsize; i++)
+                for(i = 0;i < ret; i++)
                     target_grouplist[i] = tswap32(grouplist[i]);
                 unlock_user(target_grouplist, arg2, gidsetsize * 4);
             }