65936bf25f
ipoib_mcast_carrier_on_task() insanely open codes a rtnl_lock() such that
the only time flush_workqueue() can be called is if it also clears
IPOIB_FLAG_OPER_UP.
Thus the flush inside ipoib_flush_ah() will deadlock if it gets unlucky
enough, and lockdep doesn't help us to find it early:
CPU0 CPU1 CPU2
__ipoib_ib_dev_flush()
down_read(vlan_rwsem)
ipoib_vlan_add()
rtnl_trylock()
down_write(vlan_rwsem)
ipoib_mcast_carrier_on_task()
while (!rtnl_trylock())
msleep(20);
ipoib_flush_ah()
flush_workqueue(priv->wq)
Clean up the ah_reaper related functions and lifecycle to make sense:
- Start/Stop of the reaper should only be done in open/stop NDOs, not in
any other places
- cancel and flush of the reaper should only happen in the stop NDO.
cancel is only functional when combined with IPOIB_STOP_REAPER.
- Non-stop places were flushing the AH's just need to flush out dead AH's
synchronously and ignore the background task completely. It is fully
locked and harmless to leave running.
Which ultimately fixes the ABBA deadlock by removing the unnecessary
flush_workqueue() from the problematic place under the vlan_rwsem.
Fixes:
|
||
|---|---|---|
| Documentation | ||
| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| 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.
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.