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Swap only altered elements of the grouplist in getgroups() (Kirill Shutemov).

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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
This commit is contained in:
balrog 2008-09-20 02:12:08 +00:00
parent cb3bc23361
commit a2155fcc65
1 changed files with 2 additions and 2 deletions
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4
linux-user/syscall.c
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@ -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); target_grouplist = lock_user(VERIFY_WRITE, arg2, gidsetsize * 2, 0);
if (!target_grouplist) if (!target_grouplist)
goto efault; goto efault;
for(i = 0;i < gidsetsize; i++) for(i = 0;i < ret; i++)
target_grouplist[i] = tswap16(grouplist[i]); target_grouplist[i] = tswap16(grouplist[i]);
unlock_user(target_grouplist, arg2, gidsetsize * 2); 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; ret = -TARGET_EFAULT;
goto fail; goto fail;
} }
for(i = 0;i < gidsetsize; i++) for(i = 0;i < ret; i++)
target_grouplist[i] = tswap32(grouplist[i]); target_grouplist[i] = tswap32(grouplist[i]);
unlock_user(target_grouplist, arg2, gidsetsize * 4); unlock_user(target_grouplist, arg2, gidsetsize * 4);
} }