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DMA RX completion handler for UART is called from a tasklet and hence may be delayed depending on the system load. In meanwhile, there may be RX timeout interrupt which can get serviced first before DMA RX completion handler is executed for the completed transfer. omap_8250_rx_dma_flush() which is called on RX timeout interrupt makes sure that the DMA RX buffer is pushed and then the FIFO is drained and also queues a new DMA request. But, when DMA RX completion handler executes, it will erroneously flush the currently queued DMA transfer which sometimes results in data corruption and double queueing of DMA RX requests. Fix this by checking whether RX completion is for the currently queued transfer or not. And also hold port lock when in DMA completion to avoid race wrt RX timeout handler preempting it. Signed-off-by: Vignesh R <vigneshr@ti.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.