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[ Upstream commit 07300f774fec9519663a597987a4083225588be4 ] After device is stopped we reset the rings by moving all free buffers to positions [0, cnt - 2], and clear the position cnt - 1 in the ring. We then proceed to clear the read/write pointers. This means that if we try to reset the ring again the code will assume that the next to fill buffer is at position 0 and swap it with cnt - 1. Since we previously cleared position cnt - 1 it will lead to leaking the first buffer and leaving ring in a bad state. This scenario can only happen if FW communication fails, in which case the ring will never be used again, so the fact it's in a bad state will not be noticed. Buffer leak is the only problem. Don't try to move buffers in the ring if the read/write pointers indicate the ring was never used or have already been reset. nfp_net_clear_config_and_disable() is now fully idempotent. Found by code inspection, FW communication failures are very rare, and reconfiguring a live device is not common either, so it's unlikely anyone has ever noticed the leak. Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> Reviewed-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.