Jeff Layton 2005f5b9c3 lockd: fix races in client GRANTED_MSG wait logic
After the wait for a grant is done (for whatever reason), nlmclnt_block
updates the status of the nlm_rqst with the status of the block. At the
point it does this, however, the block is still queued its status could
change at any time.

This is particularly a problem when the waiting task is signaled during
the wait. We can end up giving up on the lock just before the GRANTED_MSG
callback comes in, and accept it even though the lock request gets back
an error, leaving a dangling lock on the server.

Since the nlm_wait never lives beyond the end of nlmclnt_lock, put it on
the stack and add functions to allow us to enqueue and dequeue the
block. Enqueue it just before the lock/wait loop, and dequeue it
just after we exit the loop instead of waiting until the end of
the function. Also, scrape the status at the time that we dequeue it to
ensure that it's final.

Reported-by: Yongcheng Yang <yoyang@redhat.com>
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2063818
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2023-04-26 09:05:00 -04:00
2023-02-26 11:53:25 -08:00
2022-09-28 09:02:20 +02:00
2022-10-10 12:00:45 -07:00
2023-04-16 15:23:53 -07:00

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.
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