fix(iovec): do not return error if some bytes were written #5485
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When reading from a volatile memory into a WriteVolatile we should let the caller know if we managed to transfer some bytes. Currently, if the write encounters any error after the first iovec an error is returned, but some bytes are written. This causes issues in the caller, because it thinks no bytes were written. In particular, this caused a bug in the vsock code on 6.17 guest kernels because these kernels started sending multiple iovecs. When sending 2 iovecs, it could happen that we'd get a WouldBlock error on the second, but the vsock code thought no bytes were transferre, leading to a spurious retransmission of the first iovec. Fixes: firecracker-microvm#5475 Signed-off-by: Riccardo Mancini <[email protected]>
As in the previous commit, the same erroneous pattern is present also in write_volatile_at. Fix it there as well. Signed-off-by: Riccardo Mancini <[email protected]>
Adds an entry to the changelog for the iovec fix. Signed-off-by: Riccardo Mancini <[email protected]>
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kalyazin
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bchalios
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Changes
When reading from a volatile memory into a WriteVolatile we should let the caller know if we managed to transfer some bytes. Currently, if the write encounters any error after the first iovec an error is returned, but some bytes are written. This causes issues in the caller, because it thinks no bytes were written.
In particular, this caused a bug in the vsock code on 6.17 guest kernels because these kernels started sending multiple iovecs. When sending 2 iovecs, it could happen that we'd get a WouldBlock error on the second, but the vsock code thought no bytes were transferre, leading to a spurious retransmission of the first iovec.
Reason
Fixes: #5475
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CONTRIBUTING.md.PR Checklist
tools/devtool checkbuild --allto verify that the PR passesbuild checks on all supported architectures.
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how they are solving the problem in a clear and encompassing way.
in the PR.
CHANGELOG.md.Runbook for Firecracker API changes.
integration tests.
TODO.rust-vmm.