passt/iov.h, branch bug165c

tap: Use iov_tail with tap_add_packet()

2025-09-03T18:42:20+00:00

Use IOV_PEEK_HEADER() to get the ethernet header from the iovec.

Move the workaround about multiple iovec array from vu_handle_tx() to
tap_add_packet(). Removing the offset out of the iovec array should
reduce the iovec count to 1.

Signed-off-by: Laurent Vivier 
Reviewed-by: David Gibson 
Signed-off-by: Stefano Brivio

iov: Update IOV_REMOVE_HEADER() and IOV_PEEK_HEADER()

2025-09-03T18:42:17+00:00

Provide a temporary variable of the wanted type to store
the header if the memory in the iovec array is not contiguous.

Signed-off-by: Laurent Vivier 
Reviewed-by: David Gibson 
Signed-off-by: Stefano Brivio

iov: Introduce iov_tail_clone() and iov_drop_header().

2025-09-03T18:42:15+00:00

These utilities enhance iov_tail manipulation, useful for
efficient packet processing by enabling iovec array cloning and
header stripping without data copies.

- iov_drop_header(): Discards a specified number of bytes from the
  beginning of an iov_tail by advancing its internal offset and pruning
  consumed elements.

- iov_tail_clone(): Clone an iov_tail into an iovec array, adjusting the
first iovec entry to remove the iov_tail offset.

Signed-off-by: Laurent Vivier 
Reviewed-by: David Gibson 
Signed-off-by: Stefano Brivio

style: Fix 'Return' comment style

2025-07-18T17:19:24+00:00

We always use imperative (no 'Returns:'), no tab after the ':' and
only one space, the first character is always lowercase.

This is fixed with:

 sed -i "s/Returns:/Return:/;s/Return:    /Return: /;s/Return:  */Return: /;s/Return: \([A-Z]\)/Return: \L\1/" *.[ch]

And manually updated to fix alignment of multiline comment and words
that must keep uppercase (like IPv4, TCP, UDP, Layer-4).

Signed-off-by: Laurent Vivier 
Signed-off-by: Stefano Brivio

iov: iov tail helpers

2024-11-28T13:03:16+00:00

In the vhost-user code we have a number of places where we need to locate
a particular header within the guest-supplied IO vector.  We need to work
out which buffer the header is in, and verify that it's contiguous and
aligned as we need.  At the moment this is open-coded, but introduce a
helper to make this more straightforward.

We add a new datatype 'struct iov_tail' representing an IO vector from
which we've logically consumed some number of headers.  The IOV_PULL_HEADER
macro consumes a new header from the vector, returning a pointer and
updating the iov_tail.

Signed-off-by: David Gibson 
Signed-off-by: Stefano Brivio

iov: remove iov_copy()

2024-06-13T13:45:40+00:00

it was needed by a draft version of vhost-user, it is not needed
anymore.

Signed-off-by: Laurent Vivier 
Reviewed-by: David Gibson 
Signed-off-by: Stefano Brivio

iov: Helper macro to construct iovs covering existing variables or fields

2024-05-02T14:13:31+00:00

Laurent's recent changes mean we use IO vectors much more heavily in the
TCP code.  In many of those cases, and few others around the code base,
individual iovs of these vectors are constructed to exactly cover existing
variables or fields.  We can make initializing such iovs shorter and
clearer with a macro for the purpose.

Signed-off-by: David Gibson 
Signed-off-by: Stefano Brivio

iov: Improve documentation of iov_skip_bytes()

2024-03-07T22:09:15+00:00

As pointed out in review, the documentation comments for iov_skip_bytes()
are more confusing than they should be.  Reword them, including updating
parameter names, to make it clearer.

Signed-off-by: David Gibson 
Signed-off-by: Stefano Brivio

iov: Add helper to find skip over first n bytes of an io vector

2024-02-29T05:24:07+00:00

Several of the IOV functions in iov.c, and also tap_send_frames_passt()
needs to determine which buffer element a byte offset into an IO vector
lies in.  Split this out into a helper function iov_skip_bytes().

Signed-off-by: David Gibson 
Signed-off-by: Stefano Brivio

iov: add some functions to manage iovec

2024-02-29T05:23:49+00:00

Introduce functions to copy to/from a buffer from/to an iovec array,
to compute data length in in bytes of an iovec and to copy memory from
an iovec to another.

iov_from_buf(), iov_to_buf(), iov_size(), iov_copy().

Signed-off-by: Laurent Vivier 
Message-ID: <20240217150725.661467-2-lvivier@redhat.com>
[dwg: Small changes to suppress cppcheck warnings]
Signed-off-by: David Gibson 
Signed-off-by: Stefano Brivio