On Friday, April 05, 2013 9:52 PM, Ian Abbott wrote: > On 06/04/13 00:07, H Hartley Sweeten wrote: >> The struct file_operations (*read) and (*write) operations expect the >> buffer to be a __user space pointer. >> >> Currently the (*write) operations in this driver cause this warning: >> warning: incorrect type in argument 2 (different address spaces) >> expected char const [noderef] <asn:1>*<noident> >> got unsigned char [usertype] *buf >> >> And the (*read) operations cause this warning: >> warning: incorrect type in argument 2 (different address spaces) >> expected char [noderef] <asn:1>*<noident> >> got unsigned char *<noident> >> >> Use __force to cast the buffer to a __user pointer to suppress the >> warnings. > > The sparse warnings are probably helpful in this case. They indicate > the driver is doing something wrong! Using __force just masks the problem. Normally I would agree, but in this case I don't think so. The tty read/write in this driver is not directly initiated by user space and we don't have a __user buffer to pass to the read/write functions. I guess the kernel buffers could be copied to __user buffers, use that buffer, then copy the data back to the kernel buffer, but that seems like unnecessary overhead. Take a look at __kernel_write() in fs/read_write.c for a similar example that is already in the kernel. Regards, Hartley _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
