On Wed 2020-10-14 23:27:46, Matteo Croce wrote: > From: Matteo Croce <mcroce@xxxxxxxxxxxxx> > > The kernel cmdline reboot= argument allows to specify the CPU used > for rebooting, with the syntax `s####` among the other flags, e.g. > > reboot=soft,s4 > reboot=warm,s31,force > > In the early days the parsing was done with simple_strtoul(), later > deprecated in favor of the safer kstrtoint() which handles overflow. > > But kstrtoint() returns -EINVAL if there are non-digit characters > in a string, so if this flag is not the last given, it's silently > ignored as well as the subsequent ones. > > To fix it, use _parse_integer() which still handles overflow, but > restores the old behaviour of parsing until a non-digit character > is found. Hmm, _parse_integer() is an internal function. And even the comment says "Don't you dare use this function." I guess the it is because the base must be hardcoded. And KSTRTOX_OVERFLOW bit must be handled. I suggest to go back to simple_strtoul(). It is not longer obsolete. It still exists because it is needed for exactly this purpose, see the comment in include/linux/kernel.h The potentional overflow is not a big deal. The result will be that the system will reboot on another rCPU than expected. But it might happen also with any typo. > While at it, limit the CPU number to num_possible_cpus(), > because setting it to a value lower than INT_MAX but higher > than NR_CPUS produces the following error on reboot and shutdown: Great catch! Please, fix this in a separate patch. Best Regards, Petr
