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Early alpha processors cannot write a single byte or word; they read 8 bytes, modify the value in registers and write back 8 bytes. The type blk_status_t is defined as one byte, it is often written asynchronously by I/O completion routines, this asynchronous modification can corrupt content of nearby bytes if these nearby bytes can be written simultaneously by another CPU. - one example of such corruption is the structure dm_io where "blk_status_t status" is written by an asynchronous completion routine and "atomic_t io_count" is modified synchronously - another example is the structure dm_buffer where "unsigned hold_count" is modified synchronously from process context and "blk_status_t write_error" is modified asynchronously from bio completion routine This patch fixes the bug by changing the type blk_status_t to 32 bits if we are on Alpha and if we are compiling for a processor that doesn't have the byte-word-extension. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Cc: stable@vger.kernel.org # 4.13+ Signed-off-by: Jens Axboe <axboe@kernel.dk>
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.