public inbox for [email protected]
 help / color / mirror / Atom feed
From: Christoph Hellwig <[email protected]>
To: Alexander Viro <[email protected]>
Cc: Andrew Morton <[email protected]>,
	Jens Axboe <[email protected]>, Arnd Bergmann <[email protected]>,
	David Howells <[email protected]>,
	David Laight <[email protected]>,
	[email protected],
	[email protected], [email protected],
	[email protected], [email protected],
	[email protected], [email protected],
	[email protected], [email protected],
	[email protected], [email protected],
	[email protected], [email protected],
	[email protected], [email protected],
	[email protected], [email protected],
	David Laight <[email protected]>,
	David Laight <[email protected]>
Subject: [PATCH 02/11] mm: call import_iovec() instead of rw_copy_check_uvector() in process_vm_rw()
Date: Mon, 21 Sep 2020 16:34:25 +0200	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

From: David Laight <[email protected]>

This is the only direct call of rw_copy_check_uvector().  Removing it
will allow rw_copy_check_uvector() to be inlined into import_iovec(),
while only paying a minor price by setting up an otherwise unused
iov_iter in the process_vm_readv/process_vm_writev syscalls that aren't
in a super hot path.

Signed-off-by: David Laight <[email protected]>
[hch: expanded the commit log, pass CHECK_IOVEC_ONLY instead of 0 for the
      compat case, handle CHECK_IOVEC_ONLY in iov_iter_init]
Signed-off-by: Christoph Hellwig <[email protected]>
---
 lib/iov_iter.c         |  2 +-
 mm/process_vm_access.c | 33 ++++++++++++++++++---------------
 2 files changed, 19 insertions(+), 16 deletions(-)

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 5e40786c8f1232..db54588406dfae 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -443,7 +443,7 @@ void iov_iter_init(struct iov_iter *i, unsigned int direction,
 			const struct iovec *iov, unsigned long nr_segs,
 			size_t count)
 {
-	WARN_ON(direction & ~(READ | WRITE));
+	WARN_ON(direction & ~(READ | WRITE | CHECK_IOVEC_ONLY));
 	direction &= READ | WRITE;
 
 	/* It will get better.  Eventually... */
diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c
index 29c052099affdc..40cd502c337534 100644
--- a/mm/process_vm_access.c
+++ b/mm/process_vm_access.c
@@ -264,7 +264,7 @@ static ssize_t process_vm_rw(pid_t pid,
 	struct iovec iovstack_r[UIO_FASTIOV];
 	struct iovec *iov_l = iovstack_l;
 	struct iovec *iov_r = iovstack_r;
-	struct iov_iter iter;
+	struct iov_iter iter_l, iter_r;
 	ssize_t rc;
 	int dir = vm_write ? WRITE : READ;
 
@@ -272,23 +272,25 @@ static ssize_t process_vm_rw(pid_t pid,
 		return -EINVAL;
 
 	/* Check iovecs */
-	rc = import_iovec(dir, lvec, liovcnt, UIO_FASTIOV, &iov_l, &iter);
+	rc = import_iovec(dir, lvec, liovcnt, UIO_FASTIOV, &iov_l, &iter_l);
 	if (rc < 0)
 		return rc;
-	if (!iov_iter_count(&iter))
+	if (!iov_iter_count(&iter_l))
 		goto free_iovecs;
 
-	rc = rw_copy_check_uvector(CHECK_IOVEC_ONLY, rvec, riovcnt, UIO_FASTIOV,
-				   iovstack_r, &iov_r);
+	rc = import_iovec(CHECK_IOVEC_ONLY, rvec, riovcnt, UIO_FASTIOV, &iov_r,
+			  &iter_r);
 	if (rc <= 0)
 		goto free_iovecs;
 
-	rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write);
+	rc = process_vm_rw_core(pid, &iter_l, iter_r.iov, iter_r.nr_segs,
+				flags, vm_write);
 
 free_iovecs:
 	if (iov_r != iovstack_r)
 		kfree(iov_r);
-	kfree(iov_l);
+	if (iov_l != iovstack_l)
+		kfree(iov_l);
 
 	return rc;
 }
@@ -322,30 +324,31 @@ compat_process_vm_rw(compat_pid_t pid,
 	struct iovec iovstack_r[UIO_FASTIOV];
 	struct iovec *iov_l = iovstack_l;
 	struct iovec *iov_r = iovstack_r;
-	struct iov_iter iter;
+	struct iov_iter iter_l, iter_r;
 	ssize_t rc = -EFAULT;
 	int dir = vm_write ? WRITE : READ;
 
 	if (flags != 0)
 		return -EINVAL;
 
-	rc = compat_import_iovec(dir, lvec, liovcnt, UIO_FASTIOV, &iov_l, &iter);
+	rc = compat_import_iovec(dir, lvec, liovcnt, UIO_FASTIOV, &iov_l, &iter_l);
 	if (rc < 0)
 		return rc;
-	if (!iov_iter_count(&iter))
+	if (!iov_iter_count(&iter_l))
 		goto free_iovecs;
-	rc = compat_rw_copy_check_uvector(CHECK_IOVEC_ONLY, rvec, riovcnt,
-					  UIO_FASTIOV, iovstack_r,
-					  &iov_r);
+	rc = compat_import_iovec(CHECK_IOVEC_ONLY, rvec, riovcnt, UIO_FASTIOV,
+				 &iov_r, &iter_r);
 	if (rc <= 0)
 		goto free_iovecs;
 
-	rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write);
+	rc = process_vm_rw_core(pid, &iter_l, iter_r.iov, iter_r.nr_segs,
+				flags, vm_write);
 
 free_iovecs:
 	if (iov_r != iovstack_r)
 		kfree(iov_r);
-	kfree(iov_l);
+	if (iov_l != iovstack_l)
+		kfree(iov_l);
 	return rc;
 }
 
-- 
2.28.0


  parent reply	other threads:[~2020-09-21 14:36 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 ` Christoph Hellwig [this message]
2020-09-21 14:48   ` [PATCH 02/11] mm: call import_iovec() instead of rw_copy_check_uvector() in process_vm_rw() Matthew Wilcox
2020-09-21 15:02   ` Al Viro
2020-09-21 15:21     ` David Laight
2020-09-21 15:29       ` Al Viro
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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox