21a5d4c3a4
Sometimes, it is required to stop the transmissions momentarily and resume it later; stopping the txqs becomes very critical in scenarios where the packet transmission has to be ceased completely. For example, during the hardware restart, during off channel operations, when initiating CSA(upon detecting a radar on the DFS channel), etc. The TX queue stop/start logic in mac80211 works well in stopping the TX when drivers make use of netdev queues, i.e, when Qdiscs in network layer take care of traffic scheduling. Since the devices implementing wake_tx_queue can run without Qdiscs, packets will be handed to mac80211 directly without queueing them in the netdev queues. Also, mac80211 does not invoke any of the netif_stop_*/netif_wake_* APIs if wake_tx_queue is implemented. Since the queues are not stopped in this case, transmissions can continue and this will impact negatively on the operation of the wireless device. For example, During hardware restart, we stop the netdev queues so that packets are not sent to the driver. Since ath10k implements wake_tx_queue, TX queues will not be stopped and packets might reach the hardware while it is restarting; this can make hardware unresponsive and the only possible option for recovery is to reboot the entire system. There is another problem to this, it is observed that the packets were sent on the DFS channel for a prolonged duration after radar detection impacting the channel closing time. We can still invoke netif stop/wake APIs when wake_tx_queue is implemented but this could lead to packet drops in network layer; adding stop/start logic for software TXQs in mac80211 instead makes more sense; the change proposed adds the same in mac80211. Signed-off-by: Manikanta Pubbisetty <mpubbise@codeaurora.org> Signed-off-by: Johannes Berg <johannes.berg@intel.com> |
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| Documentation | ||
| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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 Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
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.