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Sometimes the exec_op parser does not choose the optimal pattern if multiple patterns with optional elements are available. Since the stack automatically splits operations in multiple exec_op calls, a non-optimal pattern gets broken up into multiple calls. E.g. an OOB read using the vf610 driver: nand: executing subop: nand: ->CMD [0x00] nand: ->ADDR [5 cyc: 00 08 ea 94 02] nand: ->CMD [0x30] nand: ->WAITRDY [max 200000 ms] nand: DATA_IN [64 B] nand: executing subop: nand: CMD [0x00] nand: ADDR [5 cyc: 00 08 ea 94 02] nand: CMD [0x30] nand: WAITRDY [max 200000 ms] nand: ->DATA_IN [64 B] However, the vf610 driver has a pattern which can execute the complete command in a single go... This patch makes sure that the longest matching pattern is chosen instead of the first (potentially only partial) match. With this change the vf610 reads the OOB in a single exec_op call: nand: executing subop: nand: ->CMD [0x00] nand: ->ADDR [5 cyc: 00 08 c0 1d 00] nand: ->CMD [0x30] nand: ->WAITRDY [max 200000 ms] nand: ->DATA_IN [64 B] Reported-by: Sascha Hauer <s.hauer@pengutronix.de> Suggested-by: Boris Brezillon <boris.brezillon@collabora.com> Tested-by: Stefan Agner <stefan@agner.ch> Signed-off-by: Stefan Agner <stefan@agner.ch> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
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.