Re: [PATCH] autofs sparse fixes

[Linus Torvalds]

For cases like this, where we use a kernel pointer and do the 
"set_fs(KERNEL_DS)" thing to mak ea user-pointer routing write to kernel 
space, I suggest casting the pointer instead of the function, along with a 
comment on the "set_fs()".

Basically, something like this instead:

  static int autofs_write(struct file *file, const void *addr, int bytes)
  {
	const void __user *data;
	...

	set_fs(KERNEL_DS);
	/* This cast is legal due to the set_fs()! */
	data = (const void __user *) addr;

	...->write(file, data, bytes);
	set_fs(old_fs);
  }

See? That makes the cast more obvious, and it also makes it obvious _why_ 
the cast from kernel->user pointer is ok in this case.

		Linus

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