Hello. Ralf Baechle wrote:
+ switch (cmd) { + case WDIOC_GETSUPPORT: + ret = copy_to_user((struct watchdog_info __user *)arg, &ident, + sizeof(ident)) ? -EFAULT : 0;
Doesn't copy_to_user() return 0 or -EFAULT?
No and that's a common cause of bugs. copy_{from,to}_user returns the number of characters that could be be copied so the conversion to an error code is needed here.
But then the code above would be wrong. Actually, it returns the number of bytes that could NOT be copied as I now see.
The function takes a void argument and there is no benefit from casting to the full struct watchdog_info __user * pointer type other than maybe clarity to the human reader.
Indeed.
Ralf
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