Zitat von Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>:
On Fri, May 18, 2018 at 02:48:11PM +0000, guido@xxxxxxxxxxxxxxxxxx wrote:Zitat von Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>: > On Thu, May 17, 2018 at 07:03:30PM +0200, Guido Kiener wrote: > > +/* > > + * usbtmc_message->flags: > > + */ > > +#define USBTMC_FLAG_ASYNC 0x0001 > > +#define USBTMC_FLAG_APPEND 0x0002 > > +#define USBTMC_FLAG_IGNORE_TRAILER 0x0004 > > + > > +struct usbtmc_message { > > + void __user *message; /* pointer to header and data */ > > + __u64 transfer_size; /* size of bytes to transfer */ > > + __u64 transferred; /* size of received/written bytes */ > > + __u32 flags; /* bit 0: 0 = synchronous; 1 = asynchronous */ > > +} __attribute__ ((packed)); > > Very odd structure. Your userspace pointer is going to be totally out > of alignment on 32bit systems running on a 64bit kernel. Why have a > separate pointer at all? Why not just put the mesage at the end of this > structure directly with something like: > __u8 message[0]; > ? > Oh yes, I should know that from another project. Indead we did not test it with 32 bit applications on 64 platforms. When we use your proposal then we just can use #define USBTMC_IOCTL_WRITE _IO(USBTMC_IOC_NR, 13)?Why 13? Use the structure please, that way you know you always get it right.
Sorry. I should just read the documentation. Dave helps me. Thanks.
thanks, greg k-h
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