Re: [PATCH 02/11] mm: call import_iovec() instead of rw_copy_check_uvector() in process_vm_rw()
From: Al Viro <viro@zeniv.linux.org.uk>
Date: 2020-09-21 15:29:46
Also in:
io-uring, keyrings, linux-arch, linux-arm-kernel, linux-block, linux-fsdevel, linux-mips, linux-mm, linux-s390, linux-scsi, linux-security-module, lkml, netdev, sparclinux
On Mon, Sep 21, 2020 at 03:21:35PM +0000, David Laight wrote:
You really don't want to be looping through the array twice.
Profiles, please.
I think the 'length' check can be optimised to do something like:
for (...) {
ssize_t len = (ssize_t)iov[seg].iov_len;
ret += len;
len_hi += (unsigned long)len >> 20;
}
if (len_hi) {
/* Something potentially odd in the lengths.
* Might just be a very long fragment.
* Check the individial values. */
Add the exiting loop here.
}Far too ugly to live.