bade4be69a
I tested commit 43042b90cae1 ("svcrdma: Reduce Receive doorbell
rate") with mlx4 (IB) and software iWARP and didn't find any
issues. However, I recently got my hardware iWARP setup back on
line (FastLinQ) and it's crashing hard on this commit (confirmed
via bisect).
The failure mode is complex.
- After a connection is established, the first Receive completes
normally.
- But the second and third Receives have garbage in their Receive
buffers. The server responds with ERR_VERS as a result.
- When the client tears down the connection to retry, a couple
of posted Receives flush twice, and that corrupts the recv_ctxt
free list.
- __svc_rdma_free then faults or loops infinitely while destroying
the xprt's recv_ctxts.
Since 43042b90cae1 ("svcrdma: Reduce Receive doorbell rate") does
not fix a bug but is a scalability enhancement, it's safe and
appropriate to revert it while working on a replacement.
Fixes: 43042b90cae1 ("svcrdma: Reduce Receive doorbell rate")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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.