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1f17f7742e
John reports:
Recent refactoring of fl_change aims to use the classifier spinlock to
avoid the need for rtnl lock. In doing so, the fl_hw_replace_filer()
function was moved to before the lock is taken. This can create problems
for drivers if duplicate filters are created (commmon in ovs tc offload
due to filters being triggered by user-space matches).
Drivers registered for such filters will now receive multiple copies of
the same rule, each with a different cookie value. This means that the
drivers would need to do a full match field lookup to determine
duplicates, repeating work that will happen in flower __fl_lookup().
Currently, drivers do not expect to receive duplicate filters.
To fix this, verify that filter with same key is not present in flower
classifier hash table and insert the new filter to the flower hash table
before offloading it to hardware. Implement helper function
fl_ht_insert_unique() to atomically verify/insert a filter.
This change makes filter visible to fast path at the beginning of
fl_change() function, which means it can no longer be freed directly in
case of error. Refactor fl_change() error handling code to deallocate the
filter with rcu timeout.
Fixes: 620da4860827 ("net: sched: flower: refactor fl_change")
Reported-by: John Hurley <john.hurley@netronome.com>
Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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.