linux-kernel - [RFC PATCH 16/37] iov_iter_gap_alignment(): get rid of iterate_all

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Sun,  6 Jun 2021 19:10:30 +0000
From:   Al Viro <viro@...iv.linux.org.uk>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        David Sterba <dsterba@...e.com>,
        Miklos Szeredi <miklos@...redi.hu>,
        Anton Altaparmakov <anton@...era.com>,
        David Howells <dhowells@...hat.com>,
        Matthew Wilcox <willy@...radead.org>,
        Pavel Begunkov <asml.silence@...il.com>
Subject: [RFC PATCH 16/37] iov_iter_gap_alignment(): get rid of iterate_all_kinds()

For one thing, it's only used for iovec (and makes sense only for those).
For another, here we don't care about iov_offset, since the beginning of
the first segment and the end of the last one are ignored.  So it makes
a lot more sense to just walk through the iovec array...

We need to deal with the case of truncated iov_iter, but unlike the
situation with iov_iter_alignment() we don't care where the last
segment ends - just which segment is the last one.

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
 lib/iov_iter.c | 25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index bb7089cd0cf7..a6947301b9a0 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1409,23 +1409,26 @@ EXPORT_SYMBOL(iov_iter_alignment);
 unsigned long iov_iter_gap_alignment(const struct iov_iter *i)
 {
 	unsigned long res = 0;
+	unsigned long v = 0;
 	size_t size = i->count;
+	unsigned k;
 
-	if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
+	if (unlikely(iter_is_iovec(i))) {
 		WARN_ON(1);
 		return ~0U;
 	}
 
-	iterate_all_kinds(i, size, v,
-		(res |= (!res ? 0 : (unsigned long)v.iov_base) |
-			(size != v.iov_len ? size : 0), 0),
-		(res |= (!res ? 0 : (unsigned long)v.bv_offset) |
-			(size != v.bv_len ? size : 0)),
-		(res |= (!res ? 0 : (unsigned long)v.iov_base) |
-			(size != v.iov_len ? size : 0)),
-		(res |= (!res ? 0 : (unsigned long)v.bv_offset) |
-			(size != v.bv_len ? size : 0))
-		);
+	for (k = 0; k < i->nr_segs; k++) {
+		if (i->iov[k].iov_len) {
+			unsigned long base = (unsigned long)i->iov[k].iov_base;
+			if (v) // if not the first one
+				res |= base | v; // this start | previous end
+			v = base + i->iov[k].iov_len;
+			if (size <= i->iov[k].iov_len)
+				break;
+			size -= i->iov[k].iov_len;
+		}
+	}
 	return res;
 }
 EXPORT_SYMBOL(iov_iter_gap_alignment);
-- 
2.11.0