On 2022-07-12 4:24 PM, Andy Shevchenko wrote:
On Tue, Jul 12, 2022 at 03:51:04PM +0200, Cezary Rojewski wrote:
On 2022-07-09 10:42 PM, Andy Shevchenko wrote:
...
I still believe that casting blindly is not the way to go. I did explicitly ask about int vs u32, not int vs unsigned int. Please note that these values are later passed to the IPC handlers, and this changes the context a bit. If hw expects u32, then u32 it shall be.
What you can do is probably utilize _Generic() which will reduce the code base and allow to use the same template for different types.
Hello,
I've spent some time analyzing possible utilization of _Generic() in context of get_options() but in my opinion get_range() complicates things enough that get_range() and get_option() would basically need a copy per type.
If Linux kernel guarantees that sizeof(int), sizeof(unsigned int), sizeof(s32) and sizeof(u32) are all equal (given the currently supported arch set), then indeed modifying get_options() may not be necessary. This plus shamelessly casting (u32 *) to (int *) of course.
What's left to do is the __user helper function. What I have in mind is:
int tokenize_user_input(const char __user *from, size_t count, loff_t *ppos, int **tkns) { int *ints, nints; char *buf; int ret;
buf = kmalloc(count + 1, GFP_KERNEL); if (!buf) return -ENOMEM;
ret = simple_write_to_buffer(buf, count, ppos, from, count); if (ret != count) { ret = (ret < 0) ? ret : -EIO; goto free_buf; }
buf[count] = '\0';
get_options(buf, 0, &nints); if (!nints) { ret = -ENOENT; goto free_buf; }
ints = kcalloc(nints + 1, sizeof(*ints), GFP_KERNEL); if (!ints) { ret = -ENOMEM; goto free_buf; }
get_options(buf, nints + 1, ints); *tkns = ints; ret = 0;
free_buf: kfree(buf); return ret; }
Usage: u32 *tkns;
ret = tokenize_user_input(from, count, ppos, (int **)&tkns);
as a part of fs/libfs.c not lib/cmdline.c. Is such approach acceptable?
Regards, Czarek