From: Al Viro <viro@zeniv.linux.org.uk>
To: David Laight <David.Laight@aculab.com>
Cc: Christoph Hellwig <hch@lst.de>,
Andrew Morton <akpm@linux-foundation.org>,
Jens Axboe <axboe@kernel.dk>, Arnd Bergmann <arnd@arndb.de>,
David Howells <dhowells@redhat.com>,
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Subject: Re: [PATCH 02/11] mm: call import_iovec() instead of rw_copy_check_uvector() in process_vm_rw()
Date: Mon, 21 Sep 2020 16:29:37 +0100 [thread overview]
Message-ID: <20200921152937.GX3421308@ZenIV.linux.org.uk> (raw)
In-Reply-To: <ef67787edb2f48548d69caaaff6997ba@AcuMS.aculab.com>
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.
next prev parent reply other threads:[~2020-09-21 15:29 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-21 14:34 let import_iovec deal with compat_iovecs as well v2 Christoph Hellwig
2020-09-21 14:34 ` [PATCH 01/11] compat.h: fix a spelling error in <linux/compat.h> Christoph Hellwig
2020-09-21 14:34 ` [PATCH 02/11] mm: call import_iovec() instead of rw_copy_check_uvector() in process_vm_rw() Christoph Hellwig
2020-09-21 14:48 ` Matthew Wilcox
2020-09-21 15:02 ` Al Viro
2020-09-21 15:21 ` David Laight
2020-09-21 15:29 ` Al Viro [this message]
2020-09-21 15:44 ` David Laight
2020-09-21 16:27 ` Al Viro
2020-09-21 16:12 ` Christoph Hellwig
2020-09-21 14:34 ` [PATCH 03/11] iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c and mark it static Christoph Hellwig
2020-09-21 14:34 ` [PATCH 04/11] iov_iter: explicitly check for CHECK_IOVEC_ONLY in rw_copy_check_uvector Christoph Hellwig
2020-09-21 15:05 ` David Laight
2020-09-21 15:11 ` Al Viro
2020-09-21 15:26 ` David Laight
2020-09-21 15:07 ` Al Viro
2020-09-21 14:34 ` [PATCH 05/11] iov_iter: merge the compat case into rw_copy_check_uvector Christoph Hellwig
2020-09-21 15:14 ` Al Viro
2021-01-08 11:49 ` David Laight
2020-09-21 14:34 ` [PATCH 06/11] iov_iter: handle the compat case in import_iovec Christoph Hellwig
2020-09-21 15:20 ` Al Viro
2020-09-21 14:34 ` [PATCH 07/11] fs: remove various compat readv/writev helpers Christoph Hellwig
2020-09-21 14:34 ` [PATCH 08/11] fs: remove the compat readv/writev syscalls Christoph Hellwig
2020-09-21 14:34 ` [PATCH 09/11] fs: remove compat_sys_vmsplice Christoph Hellwig
2020-09-21 14:34 ` [PATCH 10/11] mm: remove compat_process_vm_{readv,writev} Christoph Hellwig
2020-09-21 14:34 ` [PATCH 11/11] security/keys: remove compat_keyctl_instantiate_key_iov Christoph Hellwig
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