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There is a race condition between exiting wb_on_itr and completion write
backs. For example, we are in wb_on_itr mode and a Tx completion is
generated by HW, ready to be written back, as we are re-enabling
interrupts:
HW SW
| |
| | idpf_tx_splitq_clean_all
| | napi_complete_done
| |
| tx_completion_wb | idpf_vport_intr_update_itr_ena_irq
That tx_completion_wb happens before the vector is fully re-enabled.
Continuing with this example, it is a UDP stream and the
tx_completion_wb is the last one in the flow (there are no rx packets).
Because the HW generated the completion before the interrupt is fully
enabled, the HW will not fire the interrupt once the timer expires and
the write back will not happen. NAPI poll won't be called. We have
indicated we're back in interrupt mode but nothing else will trigger the
interrupt. Therefore, the completion goes unprocessed, triggering a Tx
timeout.
To mitigate this, fire a SW triggered interrupt upon exiting wb_on_itr.
This interrupt will catch the rogue completion and avoid the timeout.
Add logic to set the appropriate bits in the vector's dyn_ctl register.
Fixes:
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|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.