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Both Dan and I have observed two processes invoking
rpcrdma_xprt_disconnect() concurrently. In my case:
1. The connect worker invokes rpcrdma_xprt_disconnect(), which
drains the QP and waits for the final completion
2. This causes the newly posted Receive to flush and invoke
xprt_force_disconnect()
3. xprt_force_disconnect() sets CLOSE_WAIT and wakes up the RPC task
that is holding the transport lock
4. The RPC task invokes xprt_connect(), which calls ->ops->close
5. xprt_rdma_close() invokes rpcrdma_xprt_disconnect(), which tries
to destroy the QP.
Deadlock.
To prevent xprt_force_disconnect() from waking anything, handle the
clean up after a failed connection attempt in the xprt's sndtask.
The retry loop is removed from rpcrdma_xprt_connect() to ensure
that the newly allocated ep and id are properly released before
a REJECTED connection attempt can be retried.
Reported-by: Dan Aloni <dan@kernelim.com>
Fixes: e28ce90083 ("xprtrdma: kmalloc rpcrdma_ep separate from rpcrdma_xprt")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.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.