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Shyam Prasad N
30b1d56452
commit5eef12c4e3upstream. The code to handle the case of server disabling multichannel was picking iface_lock with chan_lock held. This goes against the lock ordering rules, as iface_lock is a higher order lock (even if it isn't so obvious). This change fixes the lock ordering by doing the following in that order for each secondary channel: 1. store iface and server pointers in local variable 2. remove references to iface and server in channels 3. unlock chan_lock 4. lock iface_lock 5. dec ref count for iface 6. unlock iface_lock 7. dec ref count for server 8. lock chan_lock again Since this function can only be called in smb2_reconnect, and that cannot be called by two parallel processes, we should not have races due to dropping chan_lock between steps 3 and 8. Fixes:ee1d21794e("cifs: handle when server stops supporting multichannel") Reported-by: Paulo Alcantara <pc@manguebit.com> Signed-off-by: Shyam Prasad N <sprasad@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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.