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2f3be88237
The existing code had a troubling TODO statement concerning the fact that it just did a check if the page that the QEMU backend was going to read from / write to was there before the call to the QEMU backend and then relying on the fact that the page stayed around, even in a preemptible SMP kernel. Obviously the page could go away or be reassigned, and strange things may happen. Further, writes were not tracked, so any use of COW or KSM-like features would break completely. Probably that was never used by adbd (the only current active user of the pipe), but could prove much more dangerous for the GPU passthrough mechanism. Instead, use get_user_pages() as the comment suggested and cleanup the error path and add the set_page_dirt() call on a successful read operation. Also clarify the count used to return from successful read/write calls and use Linux style commentary in various places of the file. Note: The "just ignore error and return whatever we read so far" error handling is really quite horrific. I cannot change it without a more careful study of all user space ABIs reliance on this 'feature'. Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org> Signed-off-by: Jin Qian <jinqian@android.com> Signed-off-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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| goldfish_pipe.c | ||
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| pdev_bus.c | ||