Re: [PATCHv2] Check whether divisor is non-zero before division

[Alan Stern]

On Fri, May 24, 2024 at 10:13:45AM +0800, shichao lai wrote:
> On Fri, May 24, 2024 at 12:30 AM Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
> >
> > Good work!  So the problem is that the driver believes the status[0] &
> > 0x08 test.
> >
> > The way to fix this is to add an "initialized" flag to the alauda_info
> > structure.  Then alauda_check_media() should call alauda_init_media() if
> > the 0x08 bit is set in status[0] _or_ if info->initialized is 0.  And of
> > course, alauda_check_media() should then set info->initialized to 1 if
> > the alauda_init_media() call succeeds.
> >
> > Would you like to write and test a patch that does this?
> >
> > Alan Stern
> 
> I tried to do this. And the workflow can enter alauda_init_media(),
> but there are still many conditions to satisfy in alauda_init_media().
> Unfortunately alauda_init_media() stop and return here before
> initializing uzonesize:
> 
> if (data[0] != 0x14) {
>     usb_stor_dbg(us, "Media not ready after ack\n");
>     return USB_STOR_TRANSPORT_ERROR;
> }

That's an error return.

> The data[0] is status[0] showed before, and it was 0x0036.
> I am not familiar with the status code of alauda.
> How can I deal with this condition?
> Is it ok to pass this condition when info->initialized == false, even
> if the data[0] != 0x14?

If alauda_init_media() returns an error, leave info->initialized 
unchanged.  alauda_check_media() will return an error also, so the bad 
division won't take place.

Alan Stern