[PATCH next 0/3] iov: Optimise user copies

From: David Laight
Date: Fri Mar 21 2025 - 18:46:20 EST


The speculation barrier in access_ok() is expensive.

The first patch removes the initial checks when reading the iovec[].
The checks are repeated before the actual copy.

The second patch uses 'user address masking' if supported.

The third removes a lot of code for single entry iovec[].

David Laight (3):
Remove access_ok() from import_iovec()
Use masked user accesses
Optimise __import_iovec_ubuf()

lib/iov_iter.c | 97 ++++++++++++++++++++++++++++++++------------------
1 file changed, 63 insertions(+), 34 deletions(-)

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2.39.5