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 <kirill@shutemov.name>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5267 c046a42c-6fe2-441c-8c8c-71466251a162

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 4ba8880..2012eee 100644 (file)
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -5253,7 +5253,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
                 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 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
                     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);
             }